Alfa Romeo Owners Club of Australia Forum

What is the best aftermarket exhaust for 3.2 Ti,anyone put Autodelta end boxes compared to Regazzon,wizard or Novitec

Hi GTV6SA,

I have no idea, but I'd also be interested to know  :)

It used to claim an increase in horsepower on the Auto Delta description on their webpage, but it doesn't any longer.

Cheers
Stu

Someone I know who has a 159 V6 just got custom muffler deletes made up with larger chrome tips fitted.

He came on a club run a few months back and I was astounded how good it sounded. A deep sounding note with no annoying rasp.
He did mention there was a little bit of drone, but I assume that could be solved by putting in place a small hot dog resonator instead of a straight pipe.
Personally I wouldn't spend heaps of cash on brand name mufflers alone if you just want some extra sound. No real gains are to be had unless you go for a full cat back system or header back system.
Best bet would be to go down to your local exhaust shop and get them to try out different mufflers and cater it to your taste.

Andrew.

Anyone put a mille miglia exhaust system on their 159 3.2 , costs and results?

Ended getting Lambros to build a SS catback exhaust system with 2 new mufflers and 4" tips, now sounds what a V6 Alfa should be with a deep low growl.

Hello SA,

Thought I might add to this thread, as I've now read on x 2 different UK forums that the most restrictive cat's in the 159 system, are the ones at the manifolds. I'm no mechanic, not even close, but thought I should pass this on as it slightly contradicts what I wrote earlier, from information I'd been given. Downside is that fitting headers is an engine out job apparently, so this would be where the "cost of doing so" advice would apply  :)

Wizard are looking to have headers available for the V6 in their summer, this year. Hopefully they'll be a more realistic price than the ones on offer from AutoDelta

Cheers
Stu

I have been following the comments on A.O forum as well and speaking with the local Aus
Autodelta rep, I was also told that the biggest gains for HP is the catless header manifolds.Fom muboen experience in forced induction, it is really important for efficient exhaust scavenging to get rid of gasses, this can be done by equal length headers that are cc'd to make sure the volume is equal, ceramic coated headers also improve efficiency and even  the joint where the headers merge into 1 pipe.One problem with a transverse V6 ,it is very difficult   to have equal length headers on each bank due to the engine configuration without major redisign of the whole exhaust.

Scavenging, in the classic sense can only really be performed on an engine where the valve timing allows cross - flow from inlet tract to exhaust system/manifold. Unfortunately, the 3.2 JTS engine has static valve timing angles which inhibits cross - flow, given the inlet valve opens at 11.5 deg. Atdc, but the exhaust valve has closed at 9.0 deg. Atdc.

These angles appear to have been chosen to promote internal EGR to comply with emissions regulations. It also results in gutless low end torque as no charge air enters the cylinder until the piston is 11.5 degrees into its induction stroke.

So, as someone pointed out, choose an exhaust which caters for your tastes in sound as the cost of fitting a performance exhaust system can't really be justified without addressing valve timing, manifold cats and secondary cats under the car.

For those that are interested, I have detailed the work I undertook in these areas in "Enigmatic 159"


foot note - corrected valve timing angles. 

Hi Ascari, your post reminded me of information I'd read on a UK Alfa performance tuning house website. Seems they take this into account with their remap?
http://www.autolusso-penrith.co.uk/remaps.html

Cheers
Stu

Quote:- "your post reminded me of information I'd read on a UK Alfa performance tuning house website. Seems they take this into account with their remap?"

The company you refer to has a fine reputation and are well established.

However, the physical angles of the camshafts are dictated by the grind of the lobes and their position is fixed with respect to the crankshaft via the timing chain system. The internal bias of the springs within the "Phasors"/camshaft rotors ensures, whenever the engine is switched off or the driver lifts off the throttle, the pressure exerted on the camshafts will always - repeat - always, return/rotate the camshafts towards their internal end - stops. In the case of the Inlet camshaft, 11.5 degrees After Top Dead Centre and the Exhaust camshaft, 9 degrees After Top Dead Centre. No software modifications can change this.

There are several reasons for this:-

1. When the engine is switched off - starting the engine is done with the valve timing creating very little compressive load, greatly assisting the engine in firing up. The ECU also knows exactly what position this dynamic valve timing system is in, as the angles are locked by the rotor pins.

2. With this particular engine - direct injection and it's ability to use lean/ultra lean burn techniques, at tick over, the valve timing remains at these preset angles which prevents "Hunting": Camshaft Flutter due to oil pressure anomalies; as the camshaft "Lock - Pins" remain in - they do not release until the ECU opens their respective Solenoid Valves. This function is embedded within the Core ECU program for VVT management I believe. To modify this would be very dangerous - mechanically and that is why it is fixed - non adjustable.

3. Using Stratified Charge techniques, enables extremely lean burn mixtures when the driver lifts off the throttle. I.e, the AFR returns to that figure set at tick - over/low load.

A high compression ratio is not normally associated with lean mixtures as engines can be very quickly destroyed due to pre - detonation. However, the stratified charge, forming a cylindrical charge; richest at the centre and weakest at the circumference, ensures the cylinder bores/walls are cooled by the intake of air rotating around the walls and helping reduce the temperature of the exhaust valves and piston crowns, such that under normal/correct operation, the "Anti-knock" devices are never invoked. Camshaft angles and Piston Crown design play an important role in this. This is particularly important with manifold Catalytic Converters such as those fitted to the 3.2 JTS engine, the intention of which being to raise their temperature very quickly to achieve "light - Off", for proper conversion.

4. The 3.2 JTS valve timing covers a maximum range of 50 degree advance of the inlet camshaft and a 50 degree of retard of the exhaust camshaft; from their static positions, a huge range!!!!!!!!! I remain convinced the system was never designed by Alfa Romeo - it is far too sophisticated for a first attempt at quad cam VVT chain driven system, although I do believe it was designed "In - House".

With such angles, comes the real possibility of stuffing a valve into a piston crown - this is an interference engine. Modifying inlet valve timing, beyond the scope of the embedded software program, could well create pressure which at the very least could blow cylinder head gaskets and in worst case - crankshaft failure.

I believe the scope of software changes in limited to AFR and Ignition Advance/Retard. Nothing can be done about valve timing angles, without changing the camshafts. My camshafts have modified the valve timing to 0.5deg. BTDC, inlet valve opens, 23 deg. ATDC, exhaust valve closes; Static Angles. There was no other way of ridding this engine with 2.5deg. NVO -negative valve overlap. Interestingly, although my engine ticks-over; solidly, still at 750 rpm, it sounds meaty - powerful. No doubt I will have to have the AFR adjusted, although I am happy with the economy. However, it appears clear, there is a preset AFR when the camshafts are locked - rotor pins in. This is evidenced by virtue of the fact, if I apply the throttle lightly as I pull away, even before the clutch engages, there is a very slight dip in revs.

But, coming off the throttle at speed, the camshafts rotate swiftly back to their "Static positions" and the engine offers very little drag. When however, the camshafts finally do get back to their static positions, the ECU seem to apply the AFR figure to the charge. And the slight difference results in an even lesser amount of drag offered by the engine. Which is why I believe I shall have to uprate the brakes.

5. Finally, the VVT System, Valve Timing/Camshafts, along with the Piston Design and both the Manifold Cats and the Twin Cat under the car are integral to the 3.2 JTS achieving the highest ratings category - 5, I believe, for emissions. Along with the obvious safety features and superb platform/chassis, this monumental car, deserves respect. We will never get so much again from Alfa Romeo, at such a relatively low price. Best Alfa for forty years; IMHO.
       

Quote from: Stu159 on August 24, 2020, 05:45:53 AM
Hi Ascari, your post reminded me of information I'd read on a UK Alfa performance tuning house website. Seems they take this into account with their remap?
http://www.autolusso-penrith.co.uk/remaps.html

Cheers
Stu

Hi Stu,

I believe the remapping relates to Diesel engines, not the 3.2 JTS.

With the 3.2 JTS engine, exhaust gases cannot get into the inlet tract as the inlet valve remains closed until 11.5deg. ATDC. So the piston is already on it's induction stroke and for 2.5deg., NVO ensures both inlet and exhaust are closed. This partial vacuum pulls unburnt HC's + some oil past the rings, into the combustion chamber.

The highest content of pollutants are between the ring/piston and cylinder bore interface area and they are normally the last to exit the cylinder via the exhaust valve. By adopting this approach, Alfa seem to have generated internal EGR. So these pollutants do not pass into the exhaust system and then out into the environment, but remain within the cylinder to be reburnt along with the incoming charge. It is said to be very effective and pollutants are almost completely destroyed.  It also reduces the density of the charge because these components are hot and expand, reducing the inrush of air through the inlet valve - creating lean burn conditions.

That some oil makes its way past the rings is a small price to pay for upper cylinder lubrication - assisted by the spray jets in the sump. It is probably the reason for a 112,000 mile engine having cylinder bores which looked like the block had just come from the manufacturer.

 

Hi Ascari,

Probably a good time for me to slot in another quote from a previous post of mine in this thread "I'm no mechanic, not even close"  ;D
Regardless, it's all an interesting read. On that link to the U.K. tuning house, they note they install some sort of plate to offset the EGR gases, not that they do it with a remap. The remap is part of the process. There's not a lot of info there, but I'm sure someone such as yourself would find it interesting.

Thanks for taking the time to put all of this down. I love my 159 also, so I'm always interested to learn as much as I can about it and I'm sure I also speak for others in this forum in this regard

All the best
Stu

The plate blanks off the EGR valve which normally returns some exhaust gases to the inlet tract. Being hot, they also reduce the density of the charge. Without blanking it off, build up of crud can accrue in the inlet tract and also on the EGR valve itself. Indeed the plate seems to have come about as EGR valves were failing, regularly. I only changed the valve once in 170,000 miles, so maybe I was lucky. It is a practical solution lots of diesel owners have adopted.

Quote from: GTV6SA on November 02, 2018, 02:50:29 PM
What is the best aftermarket exhaust for 3.2 Ti,anyone put Autodelta end boxes compared to Regazzon,wizard or Novitec

Just inputting some further details, wrt end boxes.

The ones I have just fitted are dreadful at the moment. I shan't say who makes them - yet as it would be unfair until all processes have been gone through.

However, fitting a Supersprint centre section: stainless steel, shifted the droning at 2500 rpm from the central resonator, to the rear boxes. Believing the Alfa Boxes could not cope, I bought the ones now fitted. Brilliant over 3000 rpm - terrible below.

However, further investigation leads me to believe the central cat has now completely failed. Having removed the manifold cats in favour of Autodeltas and changed the valve timing courtesy of new camshafts, it seems like the exhaust gas pressure, in conjunction with the heat has destroyed the Ceramic twin cats.

I know Ceramic cats have a lower working temperature, but the 3.2 JTS software advances the exhaust camshaft when ever the driver lifts off the throttle. This for instance, enables cat "Light - off" temperatures to be maintained when a driver comes from cruising speeds to urban/traffic jam conditions. So there is still a lot of energy in the exhaust gases which are being discharged early into the manifold/exhaust system.

I am informed by authoritative figures that this can cause sintering of the Ceramic Honeycomb, which, although Ceramic is a good thermal insulator, it is incredibly thin walled. The excess heat can cause the precious washcoat to be stripped and channels can block/collapse.

So it appears, I have no choice but to fit a Metallic Catalytic Converter in replacement to Alfa's Twin Cat. Whilst still believing the droning is a function of the "Reed" formed by Alfa's Cat Output, it would appear, this aside, it's days would be numbered in anycase.

Lesson learned! No cylinder head temperature reduction - always an issue for me - unless the manifold cats are removed. No real performance benefit unless the camshaft timing is altered. And no real benefit from both of these, unless a free flow exhaust system is fitted. And if one is going to undertake these changes, the Alfa twin cats are too restrictive to remain, aside from their apparent inability in coping with increased temperatures.

Caveat Emptor!

PS:- choose whatever rear boxes suit your tastes and stay away from all else - unless you have very deep pockets. The performance improvement is stunning, but I'm not sure the cost can be justified. But it kept me out of trouble and it was purely an exercise in seeing how good this much maligned engine - here in UK - could be! And it is a fabulous engine in my opinion.


     

Hi Ascari, I've recently had the centre cats removed completely and the OEM muffler replaced + the rear OEM cats replaced with high flow aftermarket custom fit out. There are no droning sounds and it has a nice growl under revs, especially at high points. Not sure if it sounds as good as a Busso, but I'm yet to be outside the car to hear it. It's quite loud on warm up, when cold, but outside of that, all good. Very noticeable pick up in throttle response.

Cheers
Stu

Hi Stu,

Yes, it is really noticeable how much the throttle response improves. However, you confused me a little about what exactly it is you have swapped - out. So perhaps you could clarify for me please?

First off however, is my current set up.

1) Alfa manifold Cats - removed when engine was rebuilt and replaced with Autodelta's Headers - Stainless Steel. Principally I decided this was the right thing to do as the engine runs extremely hot and destroys oil at a hell of a rate.

2) Alfa's Centre Section has a small resonator/muffler in the propshaft tunnel, just after the twin cats under the car. It caused the exhaust system to drone at ~2500 rpm. This droning was there from the day I bought her and the exhaust system was standard. However, after the engine was modified and rebuilt with the Autodelta's and C.B. camshafts fitted, the drone became intolerably loud, again at 2500 rpm ~.

As the Alfa centre section resonator/muffler is integral to the pipe, the only option was to find a replacement which didn't have any fitted . So I found a Supersprint Stainless Steel section for a good price.

3) The S.S. section was fitted and the droning ceased. However, a lot of exhaust noise/harmonics ended up in the Back - Boxes. The Alfa ones were pretty good at low revs, but broke up badly at high revs - harmonics rattling them to bits. I then bought the boxes now fitted, thinking the problem with the alfa ones was about poor power handling. No! They made matters worse, pretty dreadful at low revs, but sublime above 3000 rpm ~ The gas flow comes alive, from the engine, all the way through to the tail pipes - delicious - reminded me of my Dellortos on my old twin cam Berlina. But, just impossible to live with below 3000 rpm as the slightest load/depression of the throttle and the car will waken the dead.

I had long suspected the Twin Centre Catalytic Converters but there is a long delivery time for a replacement Sports Cat - Supersprints are made in Italy and they are Made to order - mine is due the first week of October. So until then, I am refitting the Alfa Boxes and will have a few weeks to re - adjust myself before the new cat arrives and is fitted. I have bought a pair of new Lambdas for it as I don't want any distractions from whatever the results bring.

Assuming, this goes ok, I will again refit my new boxes, just to give them a fair hearing. I am hopeful they perform better with the new cat and the problems I currently have are genuinely due the the Alfa Twin Unit.

Now for your rig :- 1. Do you still have the Manifold Cats fitted?
                            2. Have you removed the small resonator/muffler, just after the twin "Under - car" cats?
                            3. Have you had a bespoke replacement for the Alfa Twin Cats made and fitted?
                            4. What rear boxes have you fitted - are they too, bespoke?

You are only the second person to my knowledge who has removed the central twin cats and reported the absence of droning. So I am hopeful that mine too will soon disappear. The modification and rebuild of the engine was really straight forward, albeit difficult to source parts and find an engineering shop to do it for me. Every Alfa Shop declined although Alfa would sell me a new one for mega - bucks. Eventually, it was a company that does Ford and Vauxhall competition/racing engines that undertook the work and a garage that had never dealt with Alfa's before that undertook to remove the old engine and refit the new - transfering all the ancillaries over from old to new. Both companies did brilliant jobs. I shan't comment about so called specialists! But I can understand why Alfa are in trouble over here. However, they only have themselves to blame given they give such little support to independants.

It would be helpful if you could clarify your set up for me. The process is ongoing but I am hopeful it is nearing completion. The power lift and performance is all I could hope for, even though I started this project just to get temperatures down. Well they certainly are now - even after a spirited one hour run, the inlet manifold is comfortable to touch. Previously, you could grill a steak on it!

Cheers.   
                         

Hi Ascari,

The whole system is bespoke. I'm not going to name who did it (inner Sydney specialist), because while the end result is great, the process involved in getting to that point wasn't + the associated costs (20% more than the original quote, that I had to part with as a 2nd outlay to make necessary adjustments) + repeated visits. I will never return.......

1. Do you still have the Manifold Cats fitted? yes
2. Have you removed the small resonator/muffler, just after the twin "Under - car" cats? replaced with an after market sports muffler
3. Have you had a bespoke replacement for the Alfa Twin Cats made and fitted? no, removed altogether
4. What rear boxes have you fitted - are they too, bespoke? yes, bespoke high flow
All the new gear is theirs and it's custom. Hopefully of a much higher standard than their ability to communicate....... :)

As I noted, the big difference in sound is when starting up cold, but it has a nice purr at idle once it settles and that sweet sound it always had up around peak revs, is more of a deep growl now. Noticeably louder overall, but no droning and unless you put your foot down, no louder than an old school V8 with a twin system. Next time I go to see my mechanic I'm going to get him to drive it up the road so I can have a listen  ;D

P.S. I love your passion for the 159. I've always found the purists comments about the GM block amusing. It's a great car to drive and after 116,000 k's of ownership (I bought it as a dealership demo), I have no regrets

Cheers
Stu

Thanks Stu,

Glad it all worked out in the end - but it seems a familiar story. Exhaust people here also want to lump "Development Costs" onto the customer. It is like they are doing an exhaust system for the very first time. Surely there is a degree in commonality between cars of the same class. A company here wants to sell me yet another set which they "developed", but as I point out, the gas flow is somewhat different now the man - cats have gone. What you have done seems to be similar to what this company has done although they said they were going to do cat - free manifolds some years ago.

However, whilst your engine purrs on tick - over, this thing does not. It growls! It has a meaty sound, despite ticking over at 750 rpm. I can only assume, the removal of the cats and the valve timing change the camshafts have brought, has resulted in a better AFR at tick - over.

When this engine idles, the phasor pins are in and the camshafts "Locked". And the ECU is setting the AFR according to the MAF, I think. So the mixture may well be more appropriate for slightly higher revs, but the ECU detects the throttle position and will not release the Rotors.

But there is no doubt the engine is drinking more air and exhaust gas velocities are much higher. So mufflers designed on a standard 3.2 JTS have less demand on them, because of a) the restriction of the manifold cats, b) the restriction of the central cats, and c) the standard valve timing. My engine is devoid of all three of these issues.

So I can't go down that route because when this company realises the truth of what I say, they will be lumping more money onto the boxes and pushing the price to silly levels - similar to what you experienced.

At least I have assurances from Supersprint engineering dept., that their boxes will cope and they will bear the cost of resolving the issue if they don't.

I can see genuine benefit of removing the central cat, as you have done, whilst leaving the man - cats. You will most definitely have better flow through them now and by joining the two paths directly - no central cat - the velocity of the gases, away from idle, will directly aid the flow characteristics of both banks - a real plus. And I think your engine/cylinder heads will be a bit cooler too!

However, it is clear the central cats are a problem not least because of the way they co - join. The two outlets, being squeezed into one form a "Reed" across which the gases alternately blow and generate harmonics. And because the join tangentially cause vortices/turbulent flow from there - on back.

Your throttle response has increased fundamentally because your pumping losses have reduced. Have you noticed an improvement in economy?

It is encouraging to know what you have achieved and although I have removed the manifold cats, the new Supersprint Cat is designed to unify the flow at the input and create laminar flow at the output. The union of your two banks effectively do the same. the difference being there are only the tail boxes on my car, no central resonator or muffler in place of the twin cats. So it is going to be louder regardless. I can see your system will sound sweeter and less loud than mine. But it is the thoroughly unpleasant edge to mine that is really grating on me.

So I am going back to basics - refitting the Alfa Back boxes - and allowing myself time to re-adjust, so when the sports cat is fitted, I can make some sense of what has changed. Up till now it has all been getting a little confusing. Clarity is what I need now.

Cheers

Stay Safe!

       

I love all the info Ascari! Thanks again

In answer to our question re fuel economy, you'll have to give me a while longer for that to be fully realised. I need more time to get past the enjoyment of the new acceleration & sound, before I'll be able to gauge economy. I do less than 5000 k's annually, so I don't drive that much and the conversion we've been discussing was only done a few weeks ago. I never take that much notice of fuel economy as I only fill up once every 5-6 weeks anyway, so it's not an issue. I'm going to add a remap soon also, to further enhance the exhaust.

I've read your other posts also, which are a great. Each time I replace something, I upgrade. I've gone for B16 suspension and a complete replacement of poly bushes all round, in recent years. Next is fitting my Ti seats that I recently bought & I'm planning some tweaks to the interior to compliment those. I found the improved cornering ability with the new suspension was magic, but I couldn't stay in my seat to completely enjoy it, hence going with the Ti option. Also with the seats replacement and I intend to look into the option of making the adjustments to the rear shocks accessible. It's great to have adjustable shocks, but when you need to remove the rear seat to access them, well, not so good  :D

Catch you next time and look forward to reading your updates with your exhaust set up

Stu

At eight this morning I watched as the original Alfa Boxes were fitted. 30 - 40 minutes later and the car was driven out of the servicing bay - and peace returned to the world!

I thought I would have to concentrate hard to detect the difference, but it was glaringly obvious. I had expected to attribute subtle changes to the sound, confirming my view, it is the Cat which is fundamentally the problem. Well, if only that were true - the world would be a simpler place. No! whatever noise the cats generate, is dwarfed by the racket these new back boxes were making.

So now I must tune my hearing again, such that when the S.S. Cat arrives and is fitted, the differences are obvious. Oh, if only it were that simple. But it is increasingly clear, the new back boxes cannot withstand the exhaust gas pressure and are nowhere near as good as the Alfa originals. I fitted the new nearside rear box (LHS) but I doubt that is responsible for the dramatic reduction in noise. I still need to check at higher revs where the Alfa boxes appeared to break up, but all in all, I think I made a serious mistake with the new boxes. I should have taken a little more time over deciding which to go for - S.S. or these. The S.S.'s are expensive, but in the long run I think they would have been the wise choice.

Four weeks, or there about and the new cat will be fitted. Then we shall see what we shall see. In the mean time, I have booked a fitting for two new rear tyres. I am on the legal limit now. Not many miles out of them at all, but I have been testing my mods/playing enthusiastically.

God, I just love this car. The engine, with its Mods, Cams and Manifolds is extra special. Should any engine be this flexible? At 3.2 litres, I don't know any naturally aspirated V6 engines that are. It feels a bit undergeared now.

Still looking for a Holden Badge though!

Quote from: Ascari32 on September 04, 2020, 12:36:30 AM
At eight this morning I watched as the original Alfa Boxes were fitted. 30 - 40 minutes later and the car was driven out of the servicing bay - and peace returned to the world!

I thought I would have to concentrate hard to detect the difference, but it was glaringly obvious. I had expected to attribute subtle changes to the sound, confirming my view, it is the Cat which is fundamentally the problem. Well, if only that were true - the world would be a simpler place. No! whatever noise the cats generate, is dwarfed by the racket these new back boxes were making.

So now I must tune my hearing again, such that when the S.S. Cat arrives and is fitted, the differences are obvious. Oh, if only it were that simple. But it is increasingly clear, the new back boxes cannot withstand the exhaust gas pressure and are nowhere near as good as the Alfa originals. I fitted the new nearside rear box (LHS) but I doubt that is responsible for the dramatic reduction in noise. I still need to check at higher revs where the Alfa boxes appeared to break up, but all in all, I think I made a serious mistake with the new boxes. I should have taken a little more time over deciding which to go for - S.S. or these. The S.S.'s are expensive, but in the long run I think they would have been the wise choice.

Four weeks, or thereabouts and the new cat will be fitted. Then we shall see what we shall see. In the mean time, I have booked a fitting for two new rear tyres. I am on the legal limit now. Not many miles out of them at all, but I have been testing my mods/playing enthusiastically.

God, I just love this car. The engine, with its Mods, Cams and Manifolds is extra special. Should any engine be this flexible? At 3.2 litres, I don't know any naturally aspirated V6 engines that are. It feels a bit undergeared now.

Still looking for a Holden Badge though!

The Alfa Boxes have been back on the car now for a few days and yet again I am re - adjusting to how they change the cars behaviour.

Clearly the Supersprint centre section works as the droning shifted from the resonator which is just after the under - car Cat, to the rear boxes.

However, with the new boxes fitted, below 3000 rpm is just intolerably loud with a cacophony of rasps all over the place. But what I had not appreciated was, these boxes were throwing this noise back through the system towards the undercar cat, so at some points, it sounded like the whole of the system, from the tail pipes, forward to the under - car cats were resonating. Resonance is not perhaps the right word as it implies a single tone when in fact it is a wide band racket.

It was only when I refitted the Alfa boxes that I realised this was what was going on because, on reinstating, everything sounds so "Muted".

Taking the car for a drive, aircon and fan off, windows down, clearly the only distinct sounds are from the tail pipes. So much so, I wondered whether I have been incredibly lucky as it sounded so much sweeter than I remember, prior to fitting the new boxes. Is one: the one that remains in the garage - nearside, faulty after all? Or does the one which I just bought; and is now fitted, have differing characteristics?

It comes as a bit of a shock - particularly given the expense and the grief I have endured. Apart from wanting to avoid further grief by purchasing yet another pair of boxes, on the assumption they would solve my problem, my inclination now is to live with the Alfa boxes for the foreseeable future.

True, I have not wound the engine up with the Alfa ones reinstalled. But, apart from cold start - up, it all sounds very civilized. And it seems to emphasize just how quiet this engine is. The exhaust note seems throaty and progresses up the scale without any obvious holes in the audio foot print - which marries up with the brilliant progression one gets from the throttle.

So I seem to have come full circle. I could persuade myself that the nearside box was faulty throughout and fitting the new one has highlighted just how good the Alfa boxes appear to be - well certainly that is true when compared to my new ones. But I have yet to fit the Sports Cat, which may well find the Alfa boxes wanting - again.

I think there is a problem with the old box, but not sufficient to justify the cost of this exercise to date. I will however, continue to look for another new Alfa Box to replace the existing old one - rear offside 51813723. If the car continues to behave as it does now, and given more and more Urban driving is being done by me, then I won't be unhappy. I would like to have kept the performance as was above 3000 rpm, but the price is too high - the dead can't sleep.

Besides, with the few intervening weeks remaining before the sports cat arrives, it will give me time to familiarize myself with the sound and performance so that I should be able to detect the changes the Sports Cat makes. And with increased scavenging, who knows, it might restore a little of what I think I may have lost above 3000 rpm, when I removed the faulty new boxes.

Cheers!
           

Hi Ascari,

What sort of power output are you getting with all the engine mods? I know you've changed cams but what else did you have done?

Have you thought about not worrying about sorting the exhaust note issue any further and just opting for the Holden badge option you mentioned?  ;D

Stu

Hi Stu,

I will fit Holden badges to my car, if I can find a couple of those suggested in an earlier post "Designed by Holden". Particularly if I can prize out the Lions Head and insert the Alfa Badge. It is no less than Alfa deserve for the way customers have been, firstly fleeced and then abandoned, wrt the 939 series.

However, in the meantime, my son and I have been debating what the car should now be called. He bought me a couple of Alfetta badges and suggests "Alfetta Competizione". And I favour "158 Competizione". The 158 logo should arrive today. But I see no reason why the Holden flashes can't go on the front wings.

Although I bought a failed ~ 40,000 miler Brera engine just to try to understand why this engine suffered so much criticism, very soon after my 159 engine gave up the ghost and it became necessary to either, scrap the car or rebuild one of the two engines. Alfa would have prefered I scrap the car and the Brera engine, if their attitude was anything to go by.

Parts were very difficult to source and their prices exorbitant. Alfa would graciously sell me a new one for £16,500 or a reconditioned one for £12,500. A new crank for circa £3,500.

The Brera crank was bent and wherever I went it was the same story - can't be pulled back; it will break. So provision had to be made for a new crank, from somewhere.

Step forward  "RevHigh" - take a bow! Great Aussie outfit. New crankshaft from them + shells at a fraction of the cost. Shipped Au$ 900. By this time I had inspected the Brera engine and come to appreciate what a good block it was. It was not without its problems but nothing that I though could not be resolved.

Although the 159 had new chains and tensioners fitted at 110,000 miles, I didn't want to reuse them. Step forward "Mace" - take a bow! They supplied their uprated kit and Oil Pump + Rocker Arms.

I contacted a company in the States about fabricating a windage plate and soon the Director and I established a friendly rapport. So much so, he sourced many of the research papers on the evolution of this engine and found parts which were unavailable to me in UK. For instance, the latest Spray Jet Nozzles which are much more accurate and operate at a higher pressure.

The first modifications were to the oil filter/cooler which I determined could supply the rear bank lower timing chain tensioner - direct. It was a fundamental mistake to place the principal tensioner at the end of the oil way supply. The residual pressure there, after all other services had taken their quota was far too low to maintain tension.

There was also "Three Serious Restrictions" within the block, almost immediately the oil leaves the filter/cooler. So they too were bypassed, taking the oil directly from the filter/cooler, into the front bank main oil gallery.

These first modifications were however, tested while my 159 was still running. They gained me 10 BHP as indicated on my dynamometer run. But I had still to modify my VVT's which I considered to be worth a few more horses. I estimated at the time of failure, the engine was good for ~285 HP.

At this point restoring the Brera began in earnest. Despite a new crankshaft being on its way, a local engineering company - Ivor Searle - take a bow, pulled the original crank back to within 3 thou, peigned it and inspected it for telltale fractures. None were detected and a regrind and 1st oversize crank and conrod shells were sources - Lithuania.

The Oil way mods had worked well but the sump needed modifications. Drainage from the heads appears from ducts in the sump, directly in line with the rotating crankshaft journals, whipping oil immediately into windage. Aluminium plates were welded over these openings to carry the oil directly below the windage plate and into the sump. At the same time the windage plate was extended to cover the full length of the sump, completely shrouding the oil pan from the rotating crankshaft.

The Oil pick - up for the pump sits too high above the surface of the sump floor. So a new one was acquired from the States and was modified, lowered to help eliminate oil starvation in corners. It is worth about an extra litre of oil in the sump before the pick-up is exposed. At the same time baffle (Swage) plates were welded to the sump floor to channel oil via the face of the pick - up, no matter what direction the car is travelling.

The VVT solenoids were modified to block off oil leakage, back to the drains when the camshafts were either advancing or retarding, greatly reducing the time it takes for the camshafts to re-adjust as dictated by the ECU. The rear bank exhaust camshaft positional sensor was modified and realigned to eliminate the error inherent in its location.

Every one of my Alfa's were maintained by me, until the GT and the 156. I was quite happy about that, although the 156 was the most expensive car I have ever run. I could have bought a Roller, the money that car consumed. And the 1.9 GT the cheapest - a brilliant little motor.

My 3.0 GTV is also garage maintained - a local guy I have known for over 20 years and that will continue.

But the 159 is different territory altogether. The prices are eye watering and there was no way I would allow anything done that was not under my direct control.

However, whilst having committed to restoring the Brera engine into my 159, there seemed little point if all I got from it was much the same as before.

I have used Colombo Bariani camshafts on four of my previous Alfas and they were brilliant. And, I knew of the existence of a set of C.B. Special camshafts, which have gone unsold for years. I decided I would give them a go! It was clear to me, if I was going to get engine temperatures down, different valve timing would be required.

I had already decided the Alfa Cats were going in the bin. And one would not be effective without the other. So, C.B. cams and Auto Delta headers it was then!

I thought very little about the exhaust system up until recently. I was sick to the eye teeth of the ridiculous claims made about cat - backs and all. But the drone I had a 2500 rpm, whilst livable before, when the engine was reinstalled became intolerable. And I allowed myself to be sucked in.

I have refitted the Alfa Boxes, the nearside being new and she is driving beautifully. Quiet at low revs now, in conjunction with the Supersprint centre section, no drone at 2500 rpm and loads of torque at very low rpm. 1200 rpm in 5th on rural roads is so sedate - it feels very special.

But, I just checked a few times and the rear boxes do break up a little at higher revs. I can't confirm anything yet, but again I am drawn to the Alfa Central Catalytic Converter. It just has a particular edge to it. So I must be patient - only another two - three weeks. Then all being well, if and when I can find one - a second new Alfa box will go on and that will be me finished.

After all that, It will be down to getting the bodywork polished and some cosmetic touches.

Now what is she likely to be - powerwise? I forgot to mention the crankshaft, conrods and pistons were fully balanced and am ignoring gains from more accurate VVT settings - camshaft angles are now very much more precise.

Autodelta have indicated about 8 bhp of recovered losses. The headers don't increase power, they reduce losses. So ~ 8 bhp is quite a conservative figure when one considers the reduction in pumping losses after the man - cats have gone.

Colombo Bariani state the gains made with their camshafts depend wholly upon the state of tune of the engine as a whole. So again, conservatively an increase of 10% in torque is not unreasonable. But they say, not less than 10%, so given all the work I have done - here's hoping!

Calculations based upon my Dynamometer plots indicate ~293 bhp @ 6670 rpm - neglecting the headers. However, cams and headers are mutually beneficial to each other. But ignoring this aspect 8 bhp recovered losses from the headers would take the engine to 301 bhp.

But I anticipate further gains, which cannot be confirmed until I have the car dynamometer tested. The manifolds in conjunction with the valve overlap definitely introduce a degree of scavenging that hitherto was absent. So volumetric efficiency will have improved as a function of PVO and reduced pumping losses. In combination with this is the benefit of the Supersprint Centre section and the absence of the post cat resonator/muffler.

In conjunction with these will be the new 100 CPI Sports Catalytic Converter, which in itself will not only reduce exhaust gas flow resistance, but also add considerably to scavenging, given the two flexis now combine at the input to the Cat, whereby there is transparency between gas flow from both banks - ie. they are physically connected.

I have not included the benefits of the revised VVT performance which noticeably increased torque at the bottom end and clearly this will have a marked effect at higher revs too. I originally predicted 315 to 325 bhp. I remain confident that it will be at least 315 bhp, but increasingly I suspect it is going to be nearer the upper figure.

Whatever it is, the sewing machine sweetness of the engine - reminiscent of my Alfetta GTV6 is absolutely beguiling. Whilst not wanting to tempt fate, all the ancillary components fitted to the Brera engine remain unchanged.

I have yet to suffer burnt coil packs or miss - fires. In fact, if what is reported on forums about this engines systemic failure are to be believed, clearly this is not an Alfa Engine. The car in itself is very un - Alfa like. In fact, aside from the finer details, which perhaps could have been done better, it's as good as any 3/5 series BMW, ignoring the "M's". I wouldn't swap it for any Audi or Jaguar. And, given it at least has six cylinders, it remains the second best Alfa of late - behind the Giulia 2.9 - which isn't and Alfa in any case - it's a Ferrari.                                   

Some rather interesting reading, Ascari32.

The 159 is built on the FIAT/GM 'Premium platform' https://en.wikipedia.org/wiki/Alfa_Romeo_159
The chassis have exceptional torsional rigidity.

And the engine is a GM creation that was manufactured here in Australia by Holden. The same family of engines were used in our local Commodores and also the last of the Saabs.
Tho the really powerful, twin turbo versions of the engine were only used, as far as I can tell, in the U.S. in the Cadillac CTS. A car I think was built on the same chassis as the VE/VF Commodore.
The best of the twin turbo engines used all of the very best modern methods of making lots of power, with a hugely broad torque curve. If mechanically tough enough, it would/should be able to rival the twin turbo BMW M3 and 2.9L Alfa engines. But GM seam to put all of their emphasis on their V8 powered machines.

Thanks for that Duk.

A prototype Alfa was designed around twin turbos and that was north of 400BHP:-

https://r.search.yahoo.com/_ylt=AwrJQ6DAxGlfjygAKHUM34lQ;_ylu=Y29sbwNpcjIEcG9zAzEEdnRpZANDMDQ1NF8xBHNlYwNzcg--/RV=2/RE=1600795968/RO=10/RU=https%3a%2f%2fen.wikipedia.org%2fwiki%2fAlfa_Romeo_Visconti/RK=2/RS=gerhpCGVI2zrATHTW5kzUbegy.I-

Of course the SAAB and Insignias had twin turbo versions at 2.8ltrs. I was at one point contemplating a new SAAB engine complete with all ancillaries and just over £2000 as an alternative to rebuilding the Brera engine.

The standard JTS engine performance is not enough to test the wonderful chassis the 159 Q4 sports. It really is very rigid. Happily, I am starting to see its true virtues. Strut braces are available although in standard guise it hardly seems necessary. Pushing on now, uphill on a local sweeping righthander, the car is now starting to talk to me: the Q4 system is brilliant.

However, instead of just replacing the rear P - Zeros: 235/40/18, I decided to get back to what they should have been - not least because the 40's were very noisy. So I went for 235/45/18 UniRoyal RainSport 5's. Took them on recommendation and road noise has dropped tremendously. And they were a fair price.

Just received prior notice my S.S. Cat is in transit from Denmark and should be here in the next day or two. However, another issue has just popped up - no A/C - Climate control completely dead. So just ploughing through the e-disc to see what may be going on. There is a pressure sensor on the condenser which may be the culprit, but I am really stabbing in the dark. Perhaps the garage can check it out when the cat goes on.

However, as an indication of just how well this engine is regarded, in revised form it will remain in production until 2026. And I can understand why. As good as the Busso is, casting technology has moved on and its block cannot compete with the likes of the 3.2JTS. The 3.2 JTS crankshaft is literally buried/encapsulated within the main superstructure.

Stepped bearing caps with six bolts two each side, of differing sizes, torque settings and on two levels, either side of the mains give incredible rigidity, complimented by two bolts either side from the outer walls through to the sides of the caps adding further bracing and strength making it vastly superior to anything I have come across.

The bores, cast into the block add further strength and the way the underside of the block is sculpted - almost cathedral - like - creating a continuous architectural casting must add tremendously to the overall strength. Wetting of this void, by oil, thrown by the rotating crank creates an even distribution of temperature across the whole of the blocks internal surface. It is a brilliant piece of engineering and for a mass produced engine is outstanding. Alfa completely missed that!

The Heads however -Alfa's, are a different matter altogether. If there is a limiting factor to this engine, this is where it lies.


Vauxhall Insignia and SAAB 2.8 - Twin - scroll turbo I believe.           

When I had my 159ti Q4 I felt the "best" exhaust was the factory one the car came with!  A fairly docile growl from the pipes that allowed you to hear and feel the engine.
I enjoyed the song from the engine more than the exhaust "note".  I believed I could hear and feel every cylinder ignition and resultant mixture burn.  A crispness I have never heard in anything else other than a 16 valve Sud motor or a Rotax kart engine!

Considered installing improved flow manifold cats but didn't get around to it.  Might have lost the ability though to hear and feel that lusty V6!

I don't mind loud exhausts.  Problem is they continually remind me how much energy is lost out of the exhaust by a non-turbo engine!

I arrived home to find the Supersprint Cat, sitting on the drive at the front door.

Continuing for the moment with the rear Alfa boxes, they are very civilised up to 2000 rpm. Loading the engine does not provoke break - up. But stab the throttle and there is a raspiness reminiscent of the old 1300 Sud. Lovable, but not right for the car.

Up to this point, the system is very quiet from the engine, to the tail pipes, with a nice throatiness, coming out the back. Just as it should be with no untoward noises. But from 2000; a multitude of low level sounds, combining to sound louder; if that makes sense, start emanate  along the full length from the Twin cat below, all the way back to the tail pipes.

I am making the broad assumption, these harmonics are a function of the Twin - cat: if this were not the case, they would extend to the exhaust ports of the engine. But no; the engine remains incredibly smooth although flow - through starts to sound more melodic.

I can only speculate it is the poor design of the Alfa unit - in particular the way the outputs combine. I also think, it is the central resonator/muffler that is used, principally to suppress these harmonics, which they did with my car. But progressively, the level of these products and their harmonic content, provoked the resonator/muffler into resonating, peaking at ~2500 rpm.

With the S.S. centre section fitted, the pipe has a more pronounced metallic ring/tinkle to it than the mild steel section it replaced. But this, I am convinced is only because of the harmonics generated by the twin cat.

The car is booked in for the S.S. cat to be fitted on Tuesday, so all will be revealed.  Not wanting to make it to easy for me, not only did the C/C pack up, having windows open to get a little air flow, on parking up, the drivers window failed to close! Then on the way home, it rained! Still, at least the S.S. Cat was there to greet us, package sitting in the rain with the rest of us.

The new boxes I bought may be retried at a latter date. The sound they made above 3000 rpm was to die for. And it seemed the engine was even free - er reving. But impossible to live with below. To what extent the Twin Cat was exacerbating this, needs to be established. And it may give me an opportunity to modify them a little to make them more tolerable. That is more in hope than belief.

29/9/2020 - Supersprint Catalyst fitted this morning. After what seems like a lifetime, at last - all the theory in the world becomes irrelevant. Is the Alfa cat the problem or not?

Answer - YES. The rear boxes; Alfa, hitherto breaking up badly at higher revs, no longer doing so. I cannot believe how quiet the exhaust system now. It will take some time to sink in but in essence, my new boxes will need to be refitted at the very least to determine just how much their appalling low - rev performance can be attributed to Alfa's Twin Cat.

Sound level is about a dB or so greater, but because all the spurious noises emanating from the Alfa Cat have now vanished, the perception is that the car is now actually quieter.

It will take some time to digest exactly how different the car, engine and exhaust system is, but at least the case against is proven. Quite an exercise, an expensive one at that. It would be nice to think I could refit my new tail-boxes, so that it wasn't the absolute disaster of a mistake, it appeared to be up until today. That would be a real cherry on the cake. But for the moment, I am over the moon about the improvement the S.S. Cat has made to my car.

And the engineer at SuperSprint predicted exactly what to expect. Nice to know at least he shared my belief in where the problem lay. But until that Cat was fitted, it was pure hypothesis.

Now however, it's fact!

Well done SuperSprint!

What a comprehensive thread. Serious work has gone into research, development and testing here!

I've just started researching 3.2 exhaust options and it sounds as if there are no *easy* or cheap power gains to be had, or even sound improvements.

A somewhat silly question - is the stock system 2.5"?

Hi Afelice001,

I found the best bang for your buck with regard to improving the performance of the 3.2 equipped 159 was to make the whole car more mechanically efficient.  I had a Q4Ti. 
The 159 had a bit of a reputation for eating front tyres - especially the FWD Ti model.  The AWD Ti not so bad.  Cause of the tyre consumption was excessive front negative camber.  Cause of the excessive negative camber is the 159Ti is a "lowered" standard 159.  The reduced ride height caused an increase in negative camber.  Unfortunately the 159 suspension is not adjustable for camber.

I replaced every possible rubber bush on the front end with polyurethane.  My replacement upper control arm bushes featured cam eccentrics allowing camber and caster adjustment.  This work AND careful front end alignment setup by a club sponsor allowed significant reduction (but not elimination) of negative camber.  An increase in caster is also worth pursuing.

Negative or positive camber causes "camber thrust".  This camber thrust caused by excessive negative camber can be managed by increasing toe out.  However tyre wear is excessive AND excessive toe eats up engine power by increasing the rolling resistance of the car.

A further means of improving the mechanical efficiency of the car is using low rolling resistance tyres.  In the past, this meant using very hard tyres with little grip.  Todays tyres can be significantly more efficient with regard to generating grip for a given rolling resistance.  The latest Michelin PS4s tyres, while relatively expensive, do realise measurable fuel consumption reductions. 

If the "whole car" is more efficient, for a given engine performance, it MUST accelerate quicker and achieve a higher top speed.


Colin

Quote from: afelice001 on November 11, 2020, 04:42:31 PM
What a comprehensive thread. Serious work has gone into research, development and testing here!

I've just started researching 3.2 exhaust options and it sounds as if there are no *easy* or cheap power gains to be had, or even sound improvements.

A somewhat silly question - is the stock system 2.5"?

Absolute correct about no easy or cheap power gains to be had. And Colin's observation about the standard Alfa back boxes is pretty much on the money, albeit they are quite restrictive. However, they are a substantial size so it is hardly surprising.

My problems, Post - Engine Modifications, stem from a number of factors which I simply did not appreciate at the time and only grew to understand their inter - relationship as I progressed.

1)       At start - up, the engine management system injects extra fuel to quickly get the manifold cats up to temperature. With free - flow manifolds, this rich mixture gets into the exhaust system and adds a cacophony of noise which no system can control/muffle/silence. From cold, the revs sit at about 1500 - 1600 rpm and it is only after a few minutes that is subsides, obviously the ECU predetermining that the "Cats" are now up to temperature!

         This, in my case is exacerbated by the fact that my JTS's valve timing is radically different from a standard JTS's, whereas the standard timing has 2.5deg. NVO: inlet opening 11.5deg. ATDC, whilst exhaust has closed at 9deg. ATDC. However, the crossflow created by the new cams, introduces air into the exhaust system which adds to the mischief of the rich start - up fuel.

         The effect all this noise has is to create almost panic, whilst one tries to understand what is happening. Eventually, there is an acceptance of the noise given the engine didn't explode into a million bits, but still one is at a loss to understand what is going on.

2)      Eventually, the engine settles out at a rock - steady 750 rpm. But there is power in the idle, as if the engine should be revving at 1500 - 2000 rpm. Another phenomenon which was not obvious to understand. Indeed, this was not understood properly until much later during tests on the exhaust system, Alfa's against my new one - admittedly to try and understand why the new just would not work below 3000 - ish rpm, whilst the Alfa's wouldn't work above.

         It has to be said, my thinking was being channeled in the direction of a faulty exhaust system/mismatch since the engine was modified. By which time, the Alfa Twin Cat had been replaced by the Supersprint 100cps Sports Cat and the Alfa centre section, complete with post - cat resonator replaced with Superasprints stainless steel - resonator free section.

         However, one of the differences these two elements made was to make the whole system more transparent and the racket was now firmly at the back of the car in the rear boxes.

         Not however, before realising the fuel issue extended to creating misfires, and quite severe resonating along the full length of the car, from the Supersprint cat, all the way back to the tail pipes.

3)      At this point, I began to think there may be an issue with the Standard MAF. And so, I cut the wire to pin five - output of the MAF - and placed a DVM in series, set to milliamps. It became possible to monitor the mA o/p of the MAF as the revs changed. Believing there could be some inaccuracy, I introduced various resistor values and found the tick-over subsided to more like normal and on test runs; down a particularly straight empty rural road, acceleration improved greatly - to the point where hitting the throttle a shove in the back became very pronounced.

        By this time, I had found the Bosch's data sheets and sought out the MAF for a 911 Porsche 3.8L. My logic led me to believe the 3.2 JTS MAF needed a fast response time Dr/Df to enable the ECU to set the AFR, given standard valve timing restricted the length of time the ECU had to calculate what fuel to inject.

        The new camshafts introduced 23.5deg. of crossflow (PVO) and allowed the induction stroke to begin to fill the cylinder from TDC and not 11.5deg. ATDC. Added to this, is the fact that for 2.5deg., flow through the MAF/inlet tract is "Checked" - both inlet and exhaust valves are closed. So volumetric efficiency can hardly be very good either!!!!!!!!

        However, 23.5deg. of Positive Valve Overlap (PVO) generates considerably velocity of air in the inlet tract/MAF, increased further by the downward thrust of the piston on its induction stroke. The Sports - cat and Headers actively promote this - increasing "Scavenging" enormously, whereas hitherto the Alfa valve timing had none. And this, I reasoned, was generating an error in the MAF which leads the ECU to set the wrong AFR.

        What also became patently obvious was, the Colombo Bariani camshafts greatly increased "Throttle Response" and by the same token reduced "Pumping Losses".

       My argument for choosing a Porsche MAF was that a Turbo car would have a less acute "Transfer Characteristic" than the 3.2 JTS's. By which time I decided to try my spare new 916 GTV 2.0 ltr. MAF insert. Better - much better. Idle more normal - acceleration good, but topping out at 4500rpm - just as the Bosch Data Sheet Graph indicated.

        Cue - my new 916 GTV 3.0 MAF, although it took me a while to get it off the car. At last, things were going in the right direction. Torque extending down to a little over 1000 rpm and good response. And All of a sudden - my new rear boxes are starting to sound the way they should. Lovely above 2500 - 3000 rpm and beyond - lost for words. But still, although more tolerable, not enough to retain them for anything like urban speeds. So Alfa's Boxes had to go back on.

4)     Deciding I was going in the right direction, being unable to find a Porsche insert at a sensible price, or a Bosch 0280002421 - the highest flow rate sensor on their data sheets (5), I ordered a 0280218008, which is the next one down (4) - under £32 new. Used on Volvo XC70? - perhaps this is why it was cheap - sorry Volvo owners. But being an Alfa Owner, when the boot is on the other foot, I'm gonna milk - it!

5)     The new MAF insert should be here sometime after Friday. But in the meantime, I had the Alfa boxes refitted. Gone is that glorious howl from the back boxes - dare I say "Ascari's". Colin's observation about Alfa's boxes ring true at this moment in time. True, the engine is not as free flowing as it was with the Ascaris, but they are so much more "Docile" and torque at the bottom end is noticeably more pronounced, coming in at just above tick - over. I have had a few jollies in her, given the weather is not too bad at the moment and it is a real joy to be driving her, even though it still has the GTV MAF fitted.

        The "Dead in Moscow" can return to their slumbers and with the front offside wheel bearing having been replaced a week of so ago, the quality of this car in its driving is astounding. Absolutely beautiful.

        As a footnote however, when Adam finally drove the 159 into the servicing bay to remove the Ascaris and refit Alfa's, it sounded sublime - nothing like it sounded from the drivers seat??????????????? So could it be, one of the differences between the two is due to "Acoustic Coupling". It is very long way from the tail pipes to the input of the cat and although suspended by rubber hangers, it is a rigid piece of stainless steel. And what of the chances of coupling through to the boot floor?

       It seemed to me, apart from the obvious increased restriction the Alfa boxes create, that restriction would be "Bi - directional". So the attenuation it generates in the tailpipe direction, would also exist in the reverse direction, reducing what is reflected back towards the cat!, Coupled with the physical size of the Alfa boxes, acoustic coupling must also be less through the boot floor.

       So, is it possible, my remaining problem is to find a way to isolate the Ascaris from both the body and the rest of the exhaust system, via flexible coupling and acoustic insulation in the boot? It would be nice to think it is. Because, I still can't come to terms with not hearing the top end howl the Ascaris produce.

2.5inch! 2.0inch back boxes                       
 

I have the Wizard exo with Prodrive S tips fitted to the rear boxes. Looks and sounds stunning. Next step is to decat the precats and go either Wizard or these babies from Orque..............
http://www.orque.co.jp/tuneup/kakudai/3.2jts-mani2.html

They aren't manifolds - they're works of art.

I don't think Wizard do headers - they have just finished prototyping some some back boxes. Autodelta assured me, their headers can be fitted with the engine in situ. However, my engine was being replaced so it wasn't an issue. Not sure how well it will perform without a valve timing change though. Is there any real point in gas - flowing and exhaust system with no crossflow?

Quote from: afelice001 on November 11, 2020, 04:42:31 PM
What a comprehensive thread. Serious work has gone into research, development and testing here!

I've just started researching 3.2 exhaust options and it sounds as if there are no *easy* or cheap power gains to be had, or even sound improvements.

A somewhat silly question - is the stock system 2.5"?

Bosch MAF 0280218008 arrived this morning. Quickly popped out with my wife to dispensary and shops. Car nicely warmed up and I have been getting used to the 3.0 GTV MAF fitted to the Q4. So much so, I thought it may not be a bad alternative.

However, got home and twenty minutes later, the new MAF insert is fitted. Out to my "Test Circuit" - quieter at idle, but won't know what she's like from cold till tomorrow morning.

Good at low revs - 1100 rpm in fifth really smooth and really quiet. Acceleration nice and crisp with good throttle response. Always eager for more throttle. Exhaust sound, more akin to Alfetta with no break - up from the Alfa Boxes. Miss the punchiness of the new ones, but these are really quite good compared to before. Agree with Colin's sentiments; probably best compromise.

No holes in the response with excellent progression. One can feel the urge from the engine when transiting to above 1500 rpm; lean burn technology below, so Alfa state. Generally, the impression of being a db or two quieter and a little less edgy on low throttle - would fit in with the less acute dr/df slope of the new MAF. Should make trimming the AFR easier - if I get bored.

   
I think I am done now! Just need the "Designed by Holden Badges" for the front wings and that's me finished.

Cheers, - Stay Safe!

Hi Ascari,

I was reading back through this thread last night and thought I might add a little more for your research and to benefit others. I noted that you stated that you thought the guts of the centre cats crumbled owing to your engine mods and increased temperatures. The reason I had the work done on my exhaust set up that I've noted on this thread, was because I had experienced exactly this issue. Unfortunately I can't recall how many k's my car was up to when it occurred, but I estimate around the 80k mark. At the time my mechanic just removed the insides and refitted it and that's how I drove it up until recently when I had it all modified.

I'll add that I've owned my car since new (bought as dealership demo in 2008 - approx 4000k) and until the recent exhaust mods I've noted, the car - with the exception of my suspension, has remained stock. So the issue occurred in my car, with no mods. I'm not sure how common it is?

All the best
Stuart

Hi Stuart.

Thank you for that contribution - much appreciated.

Chronologically, I had concerns about the centre cats for quite a while before contemplating the exhaust system beyond the Man - cats.

The difference their removal made was substantial, not least because of the exacerbated drone at 2500 rpm. The sequence of events that followed was the removal of the Alfa centre section and its replacement with a Supersprint stainless section. This shifted exhaust system noise towards the rear boxes, but spread the range of harmonics wide-band.

I then fitted a pair of Ascari sports boxes which were intolerably noisy. Feeling I had made a bad mistake buying them, I researched the Alfa twin cats and discovered they were ceramic. They have 500 cpi and all articles I researched indicated, a: they have a lower operating temperature, and b: excess temperatures can strip the catalyst coating and cause obstructions.

By this time, I had ordered a 100cpi Supersprint Sports Cat. It seemed obvious to me I was never going to get the Ascaris working and felt the safest option was to ask for Supersprint'S advice, particularly given their boxes are dedicated, but damned expensive.

The response I got from a senior design engineer who had many years with them was, "It is unlikely there is anything left of the internals of the Alfa twin cat, due to the temperature and pressure of the gases from my modified engine. Armed with that information, I destroyed what I though was a good spare cat I had in the garage. What fell out was substantially ceramic dust and sand - like grit, the remnants of the cat canister.

I still some time to wait until the S.S. Cat arrived, but as soon as it was fitted, the engine was transformed and refitting the Ascaris, she screamed like a banshee at 3000 rpm and above.

But still she wasn't right - the noise below that was unbearable.

I was grasping at straws at this point and reasoned the MAF may not be helping because of the radically changed valve timing. At the same time, I was starting to get some coil pack codes. So a MAF with a more progressive slope was found, after much trial and error with JTS MAF, and tests with new 2.0 GTV and 3.0 GTV MAFs.

Things started to come together and exhaust noise was starting to be more sporty and less aggressive, if you get my meaning. Eventually, all coil packs were replaced: "Delphi"s", and the engine improved yet again. At this point, the new MAF with the gentle-er slope was starting to perform better than the two GTV MAFs. Low rpm Torque coming on strong and load on the engine when cruising at seventy like nothing before. There is just a little hint of growling, where hitherto, it seemed like the engine was labouring, even though it wasn't.

The MAF element is 280 - 218 - 008. However, another device is being sought, a 280 - 002 - 421. This has a range up to 1000 Kg/Hr. Importantly however, it has an even less acute slope.

On evidence, progressively reducing the slope, as was the case using the 2.0 and then the 3.0 GTV inserts showed substantial improvements in tick over and progression compared to the 3.2 JTS MAF insert proper. This improvement continued with the fitting of the 280 - 218 - 008. So I am pretty confident the 002 - 421 will prove beneficial.

I think the 3.2 JTS MAF is bespoke to Alfa, produced for them by Bosch. So they will have a tolerance spread which enabled the Alfa "Softies" to embed a "Stock" fuel map. That I believe would take into account Alfa's peculiar valve timing. There is little I can do about that and I suspect there is little can be done without expensive software rewriting. And I don't think the difference it would make could ever justify the cost.

So, given the new cams allow for much more accurate MAF flow figures, I still believe ultimate power to be in the region of 315 + bhp. So much so, that I actually think the Ascari rear boxes deserve another chance and They will be getting one in another week or two.

But first, I have to find a 280 - 002 - 421 at a sensible price.

Further to the above, it gets incredibly tiring, continually searching the internet for parts which are at sensible prices. Particularly given the degree of uncertainty as to whether they will do the job.

However, I have found a MAF insert for a Porsche 3.8L, 911 Turbo. They are no longer produced by Bosch, or if they are, they may now have a different part number. It seems however, a 280 - 218 - 055 appears in the guise of 98660612500 for Porsche.

Manufacturer Part Number:   0280218055   Brand:   BOSCH
Reference OE Number:   0280218055 HFM-5-SF 30211 EE4129 XAM4247 558322, 38.796 7516248 FDM5038 FDM897 86248 0890212, LVMA256 VMA106 93006 1882019 15395 98660612500, 98660612501 QM1030 QM738 QM900 19706-M 19708-M, 19714 EAM029-M EAM033-M MAFS284-OE MAFS445-M, MAFS450-M 61-06448-SX V45-72-0032 330870300, WG1014276 WG1495389.

"Construction year to: 07.2004. Construction year from: 08....more   Porsche   911   2011   997 [2004-2012] Coupe   4.0 GT3 RS   Coupe   3996ccm 500HP 368KW (Petrol)"

Given this is a Turbo Flat Six, logic suggests - my logic that is - the Transfer Characteristic will have a pretty linear response, whereby output voltage does not increase excessively at the lower end of it's Kg/Hr response, so turbo boost will be much more progressive across the engine range and AFR much more accurately controlled. Otherwise, there would be a very big bang!

With this in mind, making the analogy with the airflow generated by the Positive Valve Overlap and the powerful scavenging generated by the Supersprint Sports Cat and free flow exhaust system, I am hopeful the AFR will be less variable at low kg/hr. than with the standard 3.2 JTS MAF element.

Evidence from my tests; to date, indicate the dramatically changing output of the JTS MAF at low kg/hr. contributes to exhaust system noise. With such huge valve overlap - 23.5deg. it is possible, unless there is a much more progressive change in fuel variation when the throttle is exercised,  enriched exhaust gases could be ignited within the exhaust system, albeit the percentage quite small, yet sufficient to generate considerable exhaust system noise.

Previously, coil packs breaking down; electrically, probably accounted for misfiring and incomplete burn at a time the exhaust valves opened, generating exhaust system noise. So,  by the same token, if enriched exhaust gases find their way into the system, the same phenomenon is possible. To my way of thinking, it is better that the ECU adjusts the fuel in a gentler fashion as dynamically, no engine can respond instantaneously to fuel enrichment. It is better if there is a slight lag as the engine assumes its new mean power as opposed to being over - injected with fuel prior to getting there. 

Exactly what the ideal response curve of the MAF for this to happen is something I cannot calculate. So it has to be by trial and error. The range that the Porsche MAF covers is 3.6 to 4.0 litre. And given substantially it is air flow/boost that determines their increased output, I hope it won't be too dramatically different with my 3.2 JTS and its increased induction and cross - flow.

Air through the inlet tract/MAF is already moving fast by the time the engine is at TDC, courteousy of the massive valve overlap the Colombo Bariani Camshafts have created. So the ECU should have a greater length of time to determine the correct AFR.

And it didn't cost too much for the sake of finding out!

But I would dearly love to know what it's Transfer Characteristics are! Help from any quarter would be much appreciated. 

Life is full of surprises - deciding to try a Porsche MAF insert and order one yesterday and having a delivery date for 7 days +, the element arrives within 18 hours. That has to be a Christmas record!

So one hour later, insert fitted, I go for a test drive. Floods causing havoc with the roads - friends farmhouse flooded out - I spend 20mins dodging the lakes.

Initial impressions: lost a bit of drama at lower revs but exhaust system quieter. Silky progression but not as sharp as with GTV 3.0 or the 280 - 218 - 008 insert. Throttle response less dramatic, but stab it and the exhaust sounds more civilised - mundane really. Good drivability in lower gears, torque good but more comfortable than in higher gears for the same speed!

Five miles on and ecu throws a code - assuming it is the new MAF out of range. Hopefully, it will reset when ECU learns the new profile.

Conclusions? Think I am going in the right direction. Actually think I can refit my new boxes. Even the Alfa boxes are sounding more "Sporty". Not saying it is ideal, but believe I am in the right area. Needs more testing/miles driven. But need that Engine management code to clear - of its own accord - before I am totally convinced.

Bought this Porsche insert quite cheap and quality not up to Bosch's usual build quality. However, until I am convinced about the right Transfer Characteristic, I can't justify spending more on what are essentially "Test devices".

Happy Christmas everyone - Stay Safe!

If I've learned anything reading this thread its that aftermarket exhaust install on the 3.2 is a black hole of effort and money  ;D

So true!

And again the car threw a code. Hasn't affected performance - at least I can't detect a change and I think, but can't say for certain it is due to MAF and being over rich at low revs.

The car is quick from the off but it has been unusually cold and she has never truly got warmed up.

I think; again don't know for certain, it has something to do with keeping the man cats at light - off temp, but they of course don't exist anymore. But on Start - up, extra fuel is injected to warm the cats, causing the engine to Rev @ about 1500 rpm for a minute or two before she settles down to 750 rpm. I think this and the cold weather is fouling the pre-cats and they are going out of limit.

Sitting in the cold in the supermarket car park while my wife was shopping, the exhaust was starting to reek of petrol fumes. I need to see if there is a temperature element somewhere which is functioning; normally for a standard engine, but just too low now with all the changes I have made.

She goes for MOT on Thursday so I will get some feedback after the test - but I'm not confident she is going to pass emissions.

To follow up on the previous post - best avoid the expense for what is really just cosmetic and little by way of increased performance. But if anyone goes the whole hog, the car may end up being used for track days.

But that really misses the point, for me. For one, it has been an exercise in trying to determine how good this engine could be. And failing emissions is not sufficient to condemn the exercise outright. It has never been an exercise in finding how good a dog of an engine can be made to sound, by piffling exhaust modifications. It's about outright performance, after the areas I believe to be poor, are addressed.

Secondly, it is also a question about what can be achieved without recourse to software rewrites. Principally, because I have seen so many differing views on so many issue, none of them supported by engineering evidence. There are experts who could resolve problems - quite quickly. But they come at a cost. And they are few and far between and certainly not local to me. So, it is a bit of a cleft stick really. But, I'll get there in the end.

good luck!  :D

Quote from: soakk on January 03, 2021, 06:20:07 PM
If I've learned anything reading this thread its that aftermarket exhaust install on the 3.2 is a black hole of effort and money  ;D

Seems that way. Getting more power out of the 3.2 V6 is like getting blood from a stone :D
Alfa should have started with the GM 3.6L block. Another 30-40kw would have been helpful in the 159.

You make have a point there. But I am still not convinced they wouldn't have buggered that up too!

Too much was going on within the FIAT Empire at the time and, in my opinion very little "Oversight" on the 159/Berra project. Hell, one minute they were climbing into bed with GM and the next GM are throwing two billion at Fiat to get out of the deal. And tossing in the 159 chassis/p platform for free.

Seems like GM came to their senses. No matter how much trouble they were in, a marriage to a dysfunctional  organisation such as Fiat was not the solution.

Since then, Chrysler were wedded and now they have taken a French Mistress! If anyone has a Busso, hang on to it, because Alfa Romeo has had so much Cosmetic Surgery, it is the only way to identify what they once were. :-[

Quote from: soakk on January 03, 2021, 06:20:07 PM
If I've learned anything reading this thread its that aftermarket exhaust install on the 3.2 is a black hole of effort and money  ;D

"Round, like a circle in a spiral, like a wheel within a wheel.

Never ending, or beginning, on a ever spinning ----------- ad infinitum.  https://youtu.be/qKV9bK-CBXo

So a couple or three days later, still a standing code/alarm - presumption it is Lambda/MAF related and I abandoned the car due to bitter weather.

Spent some time trying to get my head around what is going on and in particular, what the hell the ECU has to do with all this! A couple of really good articles read, authored by company that does stand alone ECU's for racers. Not really interested in exactly what they do, more the reason why they do it!

The particular area I was interested in was Wideband Lambdas fitted into the headers - Pre - cat Lambdas. The post cat lambdas can only act upon what the exhaust gases contain, after catalytic conversion. Of particular interest is the closed loop action of the manifold lambdas. Several re-reads persuaded me the MAF element I bought was providing an output voltage which resulted in the ECU setting a Fuel figure, beyond the range at which the wideband lambdas could enable the ECU to "Trim the Fuel" to within the "Lambda Tolerance/AFR" and thus the code/alarm.

And bitter conditions meant the engine was barely getting up to temperature, thus a very heavy smell of petrol from the exhaust - extra fuel injected below operating temp to help get the cats up to temperature. This was in the supermarket car park, on tick-over, whilst my wife was shopping.

This latest code/alarm occurred within a few, miles of the garage technician interrogating the ECU for historical faults/codes and having found no recent ones, reset the ECU, although standing alarms had been present when he did so.

As I understand it, the ECU is continually monitoring the AFR and storing any changes - slowly adjusting the fuel trim over a substantial period - "Standard Deviation", or long time averaging. Clearly, the mismatch was too great for the ECU to stay within bounds.

The MAF element fitted was 280 - 218 - 008. So clearly there is a problem with it's Transfer Characteristic. However, given the alarm appeared after very few short miles, I reasoned the ECU would not have had sufficient "Drive - Time" to store/average/modify the mean fuel injection quantities, before the failure occurred.

More in desperation than faith, I decided to refit the Porsche MAF Sensor. 280 - 218 - 055: AKA, 98660612501. The difference between 008 and 055, aside from the obvious is, with my 3.2 JTS there is an output from the MAF on tick - over with 008, whereas with 055 there is not; confirming my belief that it is relatively insensitive, which ties in with the fact that the Porsche 911, 3.8L is Turbo-ed. Meaning, one can remove the MAF plug with the 055 and the engine does not respond to the disconnection - no change in basal output voltage. If however, one disconnects the 008, the engine does respond with the "Weight" dropping out of the exhaust sound - less powerful although still rock steady at 750 rpm. And it's output voltage drops to it's basal figure when the MAF element is disconnected.

Importantly, with the 055 the exhaust system is considerably more sedate and the engine revs cleanly. I am hoping my initial judgement on the 055 was clouded due to the ECU having; prior to fitting last time, had an extensive history file of lambda adjustment/averaging and thus it went out of bounds when the 055 was initially changed.

The engine still had not come up to temperature after refitting 055 and the conditions were still pretty bitter, although it was not dark. So cold, I decided I would go sit in the car while it came up to temperature. But, after a short period, and the engine still quite cold, the differences became obvious and I got out of the car to have further listen at the back of the car. She was just a little uneven at tick-over but nothing that I would not be content with.

I am talking of less than ten minutes after the MAF had been changed. Realizing the A/C was on full blast, I looked through the rear screen and the engine management failure had cleared. I had to go sit in the car, just to get my head around this and in doing so, switched the A/C off. The engine settled immediately to a gentle purr. Got out the car, walked to the rear and the exhaust note was nothing like anything I have experienced during all my travails.

Of course, all this will change again, no doubt. But, it came as a huge surprise, particularly how civilised the exhaust sounded. And it reassures me - if it is like this now, then regardless of what other issues pop up amongst the general malaise, it can be like this again. And if I can make it thus - I'll be very - very happy.

However - let's see what tomorrow brings!       

https://www.alibaba.com/product-detail/LUFTMASSENMESSER-SENSOR-MAF-FOR-PORSCHE-0_60112075050.html

I stumbled over this too! "Circles". If this is correct and I have no reason not to, seems the Porsche insert is pretty universal. Some Alfa models seem to share this element with not just Porsche, but the Ferrari 599 GT.

And yet when one thinks of Porsche and Ferrari, one would never believe something as pedestrian as a 159 JTS "Tank" could have anything in common. A 147 maybe, as relatively speaking it carries the weight of a Gazelle; the 159/Berra, a Hippopotamus.

Paris5garage for me, and the Wizard, which is very Ferrari - like.

But more than one or two, seem to generate more racket from under the bonnet than the exhaust - like someone threw a load of nuts and bolts into the engines - awful! All that spitting and backfiring too -  must be "Hooked on timing chain slap!"

And at least one has chronic asthma! And I bet none of them get much more than five or six extra horses from them. Not much of a return for the expense.

Come on! How can anyone do this to such a fabulous coupe'? A fantastic platform for something really - really special.

It will be "Go - Faster Stripes" next!

Mind you, I can't say too much given the grief I am suffering. But hey! Anyone who owns an Alfa has chronic masochistic tendencies!

Guilty, but I love them.

Quote from: Ascari32 on January 08, 2021, 04:10:11 AM

Quote from: soakk on January 03, 2021, 06:20:07 PM
If I've learned anything reading this thread its that aftermarket exhaust install on the 3.2 is a black hole of effort and money  ;D

"Round, like a circle in a spiral, like a wheel within a wheel.

Never ending, or beginning, on a ever spinning ----------- ad infinitum.  https://youtu.be/qKV9bK-CBXo

So a couple or three days later, still a standing code/alarm - presumption it is Lambda/MAF related and I abandoned the car due to bitter weather.

Spent some time trying to get my head around what is going on and in particular, what the hell the ECU has to do with all this! A couple of really good articles read, authored by company that does stand alone ECU's for racers. Not really interested in exactly what they do, more the reason why they do it!

The particular area I was interested in was Wideband Lambdas fitted into the headers - Pre - cat Lambdas. The post cat lambdas can only act upon what the exhaust gases contain, after catalytic conversion. Of particular interest is the closed loop action of the manifold lambdas. Several re-reads persuaded me the MAF element I bought was providing an output voltage which resulted in the ECU setting a Fuel figure, beyond the range at which the wideband lambdas could enable the ECU to "Trim the Fuel" to within the "Lambda Tolerance/AFR" and thus the code/alarm.

And bitter conditions meant the engine was barely getting up to temperature, thus a very heavy smell of petrol from the exhaust - extra fuel injected below operating temp to help get the cats up to temperature. This was in the supermarket car park, on tick-over, whilst my wife was shopping.

This latest code/alarm occurred within a few, miles of the garage technician interrogating the ECU for historical faults/codes and having found no recent ones, reset the ECU, although standing alarms had been present when he did so.

As I understand it, the ECU is continually monitoring the AFR and storing any changes - slowly adjusting the fuel trim over a substantial period - "Standard Deviation", or long time averaging. Clearly, the mismatch was too great for the ECU to stay within bounds.

The MAF element fitted was 280 - 218 - 008. So clearly there is a problem with it's Transfer Characteristic. However, given the alarm appeared after very few short miles, I reasoned the ECU would not have had sufficient "Drive - Time" to store/average/modify the mean fuel injection quantities, before the failure occurred.

More in desperation than faith, I decided to refit the Porsche MAF Sensor. 280 - 218 - 055: AKA, 98660612501. The difference between 008 and 055, aside from the obvious is, with my 3.2 JTS there is an output from the MAF on tick - over with 008, whereas with 055 there is not; confirming my belief that it is relatively insensitive, which ties in with the fact that the Porsche 911, 3.8L is Turbo-ed. Meaning, one can remove the MAF plug with the 055 and the engine does not respond to the disconnection - no change in basal output voltage. If however, one disconnects the 008, the engine does respond with the "Weight" dropping out of the exhaust sound - less powerful although still rock steady at 750 rpm. And it's output voltage drops to it's basal figure when the MAF element is disconnected.

Importantly, with the 055 the exhaust system is considerably more sedate and the engine revs cleanly. I am hoping my initial judgement on the 055 was clouded due to the ECU having; prior to fitting last time, had an extensive history file of lambda adjustment/averaging and thus it went out of bounds when the 055 was initially changed.

The engine still had not come up to temperature after refitting 055 and the conditions were still pretty bitter, although it was not dark. So cold, I decided I would go sit in the car while it came up to temperature. But, after a short period, and the engine still quite cold, the differences became obvious and I got out of the car to have further listen at the back of the car. She was just a little uneven at tick-over but nothing that I would not be content with.

I am talking of less than ten minutes after the MAF had been changed. Realizing the A/C was on full blast, I looked through the rear screen and the engine management failure had cleared. I had to go sit in the car, just to get my head around this and in doing so, switched the A/C off. The engine settled immediately to a gentle purr. Got out the car, walked to the rear and the exhaust note was nothing like anything I have experienced during all my travails.

Of course, all this will change again, no doubt. But, it came as a huge surprise, particularly how civilised the exhaust sounded. And it reassures me - if it is like this now, then regardless of what other issues pop up amongst the general malaise, it can be like this again. And if I can make it thus - I'll be very - very happy.

However - let's see what tomorrow brings!     

Still bitterly cold and a degree of nervousness made me reluctant to venture out, plus my wife's concern, given the prevalence of this new strain of Covid - 19. However, I persuaded her I was just going to put some fuel in the car and would pay at the pump - no human interaction. And I was really keen to find out if the absence of the engine management fault was going remain so. Plus, I was going to fill up with 99 instead of 95, just to provoke things a little.

A made a conscious decision to follow the Alfa Handbook and immediately drive off, not waiting for the engine to come up to temperature, but I showed some respect keeping the revs down and not pulling tall gears.

Before I launch into a terribly long and boring analysis of what I expected, let me just simply say, after forty minutes the car remained free of engine management alarms. Not only that, progression was really good but less willing to pull higher gears at low-ish revs. Assumed the AFR was less rich at low revs but not so low as to believe it to be wrong. Good acceleration but I was driving more "Granny - like" than usual. Engine really quiet and exhaust drone - free. But gases loading the rear boxes so they were growling a little. Cruise control at 70 was remarkably quiet - this is not the same car that droned incessantly around 2500 rpm. But the sound is more sporty and it is entirely from the Alfa rear boxes. The exhaust system; up to them, is incredibly quiet!

At tick - over; warm engine, the tail pipes are amazingly silky and quiet. A lot less meaty than hitherto and I am really quite chuffed about them. So much so, the Ascaris will have to be tried again to be absolutely fair to them.

It seems such a long time ago, since the Alfa Cat was replaced with the Supersprint Sports Cat and boxes were on an off, more times than my socks. I am hopeful, this has been a lesson I shall not forget. Things started to come together after the Coil Packs were all changed.

I devoted a lot of time, testing the MAF with various inserts after concluding the proper Alfa MAF element was no longer suitable when I made so many changes, particularly the Camshafts.

A 2.0 & 3.0 GTV MAF was tried and not being able to find a Porsche insert at a sensible price, I bought a 280 - 218 - 008 which has a higher Kg./Hr. range than the 3.0, but not as high as the Porsche Turbo 911. It was better than the 3.0 GTV's, but still not as good as I would have expected.

The important thing to remember is, I did not have the ECU reset or the standing alarms cleared. Secondly, and this I realise now was an important factor, the three elements were not so far apart: characteristic - wise, to persuade me they were totally unsuitable.

So, finally I found a 98660612501, AKA 280 - 218 - 055 which I tried, not having reset the ECU. It failed badly. engine running but certainly undrivable to any great degree and gutless. So the 008 element was refitted and that I believed was as much as I could do for the time being.

It was at this point I asked the garage to check the code alarms and reset the ECU. Possibly 6 - 10 miles further and a engine management code returned. Bloody nightmare!!!!!!!!!   

About three days later, in sheer desperation, I decide to try 98660612501 again, after, reading an excellent article on stand - alone ECU's for racers. And I might add, discovering 98660612501, AKA 280 - 218 - 055 is the correct insert for a Porsche 3.8/4.0 Turbo 911; and a Ferrari 599 GT. And the 3.2 JTS engine! Cost £41-00p. 008 cost £32-00p.

Although all the changes to my exhaust system were planned, for a considerable amount of time I believed something was seriously amiss. When in truth what was complicating matters enormously was; unappreciated by me, a) either the original MAF element was faulty, or b) it was not the correct element. I believe it was (b).

Why? Well, I did not appreciate the mechanics of the ECU properly at that time. Closed loop lambda control functions in cruise mode. When one is accelerating hard, it goes into open - loop. The 3.2 JTS also goes into open - loop when one lifts off the throttle, the vvt solenoids returning the camshafts to their "exhaust advanced/inlet retard" positions, albeit under the control of the ECU. And importantly for me, I now realise, the output voltage from the MAF returns to the figure stated for the device in Bosch Data Sheets. The fact, I now realise, I could adjust the output voltage of the MAF, at tick - over should clearly not have been possible.

The output of the MAF falling to it's Transfer Characteristic Minimum indicates to the ECU, airflow is stymied by the throttle being closed and the ECU then switches to "OPEN - LOOP" and ignores the lambda signals. It does not utilise the lambda signals at tick - over!!!! Because the ECU hitherto had been seeing a voltage above the figure stated in the data sheets, and probably embedded in the ECU's memory, it was still reading the lambda signals and adjusting the fuel flow from the injectors - hence the powerful Tick - over.

QED - until tomorrow! I hope not. Finally ------------!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!     

I finally got my car in for MOT, having been delayed due to the wait for the Airbag control module and then, me cancelling after its arrival, due to heavy snow and freezing temperatures.

COVID-19 has meant customers cannot remain on the premises while their vehicles are being tested/repaired. And it would have meant a 3 - 4 mile walk home for me.

Anyway, the garage fitted the ACM, repaired a faulty passenger side windscreen jet and did the MOT.

When I arrived to pick up the car, the certificate showed an initial test failure. The figures for emissions were well out.

However, on the second test, they were even better than they had been when the car was tested after the modified engine was re-installed? I asked why?

The mech came out and explained. After the ACM was fitted and the associated dash fault alarm cleared, he quickly cleared a post cat lambda alarm, but did nothing else as no standing alarms were displayed.

However, on doing a full interrogation, he did a complete "Wipe", as he remembered I had finally settled for the "Porsche" MAF element (055), but had not had a reset done. This took a little extra time as temperatures are still pretty chill around here - hovering around zero, with snow hanging on.

Whilst I was chatting and settling the bill, my wife sat in the car which was in the external car park. On coming out and starting the car, I noticed the engine was still warm. So, by way of finding an excuse for going on a test run, I suggested we get a few bits of shopping at the next village, about 7 miles.

Well, neglecting the fact that the Ascaris still fitted, although still sounding dreadful, they seemed less so!

But going down the hill; and up again, out through a new estate with a series of roundabouts; a string of them about a mile and a half long,  the car felt lighter, flicking gracefully through the roundabouts with ease, body sweeping left then right with ease and holding her line on the throttle, more so than hitherto - or so it seemed. Flexibility seemed to have improved even more at the bottom end!!!!

There was a perceptible difference from how she performed when I took the car to the garage, and now. Boxes still breaking up, but cleaner. After the last roundabout, up onto the slip road of the 14 and away - exhaust noise climbing less unpleasant, but still unpleasant non the less. And so on to 2500 - 3000 +. Quick - quicker! Definite change to sound with the engine seemingly just coming on song sweetly. Is it me, is it illusory? Well if it is, I hope it lasts. God, I hope there is nothing more to burst my bubble - I was back in my 1983 GTV6 and just as it was then, my wife in the passenger seat, uncomplaining as the car  piled on the speed. This, I though, is how the Q4 should have always been. Just lovely!

Miserable though the weather is, I can't control just wanting to go for a drive. Hope I get to take this to Italy - Garda in the Spring!

I've just changed my air filter to a sports one in my V6. The brand is BMC. I decided to grab one from the German company I bought my new disks & pads from a couple of weeks back, as it's not a big expense. It has made a significant change to the sound of my car, more so than I expected and I like it. You'll note further back in this thread I'd had my centre cats removed entirely and a high flow system added from there back. This noticeably changed my throttle response and I've since (as promised  ;D) had my mechanic drive it up the road for me so that I could hear it. I should add this is pre-sports filter. The sound at low revs, honestly, is OK, I wouldn't say I love it, but I don't mind it, it's here nor there, however when the revs pick up, it sounds really sweet. It's subtle still, certainly not loud but I do love it. Not sure how to describe it or what to compare it with, but its a great performance style note. The other thing I wanted to add to this thread is something I realised last night. The sports air filter seems to have fixed the droning sound inside the cabin that the high flow system had introduced. It was never obtrusive or loud enough to be annoying anyway, but it was present. Now it's gone and is replaced by the raspy sound the air filter has added. It's as though the air filter has relieved the vibration somehow? The car seems to rev a little freer, or sound like it is?

Stu

With Alfa's valve timing being what it is, anything that helps get the air into the cylinders faster has to be a welcome addition.

Also, the inlet tract is fitted with a "Helmholtz ", with the express purpose of getting rid of inlet tract resonances. So it is possible you have "shifted" any harmonics that hitherto were causing a bit of noise.

It is a difficult subject to study and understand. When I sent my Dynamometer plot to Autodelta, with a view to re - mapping, speaking to Jano later I remarked on the small dip in the upper Rev response saying the Dynamometer guy thought it may be a due to a small misfire.

One needs to understand what one is reading into issues such as these, and I didn't. However, Jano pointed out, aspects of the AFR plot in relation to the Torque/Power traces.

"It's not that", he said. "It's down to an anomaly in the inlet tract. That could change with the smallest of alterations to the plumbing".