I know I do this from time to time and it probably won't make much difference, but it's cold out there and I'm bored..............
Anyways.
Question, and maybe this is the wrong crowd, but for a road going 75 V6 (Potenziata), what do you people think would achieve the best over all driver enjoyment?
A warmed up normally aspirated 12 valve engine.
A centrifugally supercharged engine.
A twin turbocharged engine.
Every method brings to the party its own pro's and con's:
The wamed NA engine brings music, more consistant throttle behavior, the least amount of weight (something I'm leaning towards. Overall weight and where the weight is located) and would be the nicest to the transaxle (a significant concern).
But overal power and torque numbers will never match a forced fed engine.
Technically the simplest and because of the lowerer power/torque numbers, there is temptation to create a lightened gear set for the gearbox, to make the overal combination even more enthusistic and precise.
The centrifugal supercharger would allow the engine to achieve some very decent outright power numbers, but because of the progressive boost pressure nature of centrifugal superchargers, the average torque number won't be as high as a good turbo or positive displacement supercharger set up. The more progressive torque nature of the engine should be nicer to the transaxle and having a conventional exhaust system would allow a more Alfa Romeo V6 exhaust note, but stepped up a notch or 4.
Fine tuning boost pressure is more expensive than doing the same for a turbo setup, as different pulleys would have to be bought or machined to achieve a desired boost pressure. And there is no real practical/efficient way to lower boost pressure if it's needed.
Straight cut internal gears and centrifugal compressor whistle would add some music that is all its own to the Italian V6.
Done well, a pair of small turbos would give the best, highest average torque numbers. Peak power numbers may go slightly in favour of the centrifugal supercharger set up (internal back pressure of the turbos causing additional heat retention in the combustion chambers, meaning the ignition maps would probably be more conservative to keep knock at bay), but the higher average torque should have the car being effortlessly fast for basically any gear. If you haven't driven a car that has masses of torque pretty much everywhere, then I'd say you're missing out. But when you do drive such a car, going back can be a hard thing to do...............
But the high torque numbers will give the transaxle a very hard time.
Turbo's cause massive heat retention in the exhaust manifolds and turbine housings. And that heat will cause huge problems if not dealt with correctly.
Weight and where that weight is located again shows up.
The turbine housings and and turbine wheels also take lots of energy from the exhaust gasses and that changes the note of the exhaust. Much easier to keep the overal high flowing exhaust quiet, but the music tends to be lost.
Fine tuning boost pressure is easy and being able to impliment a lower boost pressure for safety is easy too. With the right programmable computer (which mine is capable of), boost pressure by gear ratio is even do-able.
Throttle behavior also tends to be rather non-linear. Not a huge problem and the elastic throttle (where the car can continue to accelerate after a decent throttle push and march onto boost, even tho you are easing off of the throttle) can be a bit of fun once you're use to it. Incidentally, the elastic throttle behavior is very mush gone in cars like the BA/BF/FG Falcon turbos, where they have an electronic throttle body. I'm sure the manufacurers 'cured' the cars of such behavior.
Cruise fuel economy should be slighly better than the centrifugal supercharger.
And strangely, creating a more simetrical engine bay look would be a bit easier.......... :o
Like I said, I'm bored. ;D
well for me the sound of naturally aspirated webers being sucked
through with great voluminous gulps of air does send the hairs on my neck off
and the reliability is another feature that I enjoy
not having to rebuild an engine every 150K
the wine of a charger is great but boring after a while
and attracts police like sharks to a carcass
I suppose it comes down to application
race or road .
Quote from: carlo rossi on June 24, 2016, 06:27:27 PM
well for me the sound of naturally aspirated webers being sucked
through with great voluminous gulps of air does send the hairs on my neck off
and the reliability is another feature that I enjoy
not having to rebuild an engine every 150K
the wine of a charger is great but boring after a while
and attracts police like sharks to a carcass
I suppose it comes down to application
race or road .
Yeah, I won't be putting any carbies on a computer controlled engine. An ITB setup could be an option, but an unlikely 1.
I'm not sure how or why you believe that carbs are more reliable.
And as for rebuilding a force fed engine after 150,000km, um again I'm not sure how you've come to that conclusion.
I know its hard to fathom my like for carbs but they are reasonably simple to tune and repair
and the sound ahhhh if i want whining I can go upstairs for that.
I dont have an electrical engineering background so for me the idea of restoring a computer controlled car
with mapping and programs that have been superseded is a nightmare
imagine attempting to redo the electrics in 20years imagine a tesla with touch screens and such ( great car but sell it after 5 years)
we have come to nexus point I believe that any vehicle built after 2000 thereabouts
will be virtually impossible to drive in 40 years time.So the idea of Classics is dead in modern cars
we as a society in our attempts and ambitions to be Greener have never been so brown
The rebuild well this is from experience turbos only live for 150k +- 20k
the unit that is,and is also a recommendation in most manuals (european)
the engines themselve s having all that extra stress do indeed wear faster, fact of life
rings,seals ,valves, bearings the lot .
you asked for preference not logic
So thats mine! but thats not to say a twin turbo is off the cards !
in fact it is is my ambition to buy the new 500hp alfa (twin turbo)
but i wont keep it more than 5 years or over 80k
I would go, and property will, a 3.2 24v gta motor, good ecu, good headers and standard engine will achieve just under 270hp atw's, and i do know a guy in vic that is making conversion kits and this is all tested and proven.
Cheers
David
Quote from: carlo rossi on June 25, 2016, 12:02:00 PM
I know its hard to fathom my like for carbs but they are reasonably simple to tune and repair
and the sound ahhhh if i want whining I can go upstairs for that.
I dont have an electrical engineering background so for me the idea of restoring a computer controlled car
with mapping and programs that have been superseded is a nightmare
imagine attempting to redo the electrics in 20years imagine a tesla with touch screens and such ( great car but sell it after 5 years)
Again, ummmmmmmmmmm, your comparisons are strange.
Carbies easy to tune??? I'll take a programmable computer over carbies any day. You haven't even mentioned ignition timing. And there's no way I'd ever consider combining forced induction, archaic ignition timing control and carbies on the 1 engine.
By the way, I'm no elctrical/electronics engineer either. Just a Fitter and Turner car enthusiast.
And going from a electrically simple car like the 75 and comparing it to a Tesla is, ummm, again, strange.
Quote from: carlo rossi on June 25, 2016, 12:02:00 PM
The rebuild well this is from experience turbos only live for 150k +- 20k
the unit that is,and is also a recommendation in most manuals (european)
the engines themselve s having all that extra stress do indeed wear faster, fact of life
rings,seals ,valves, bearings the lot .
you asked for preference not logic
So thats mine! but thats not to say a twin turbo is off the cards !
in fact it is is my ambition to buy the new 500hp alfa (twin turbo)
but i wont keep it more than 5 years or over 80k
My Falcon turbo would spend a very small amount of it's driving life on boost and I would expect similar boost/dring behavior from most turbo cars. The Falcon is also my 4th force fed car and I haven't seen anything like the bad engine/turbo life you've mentioned from any of them and 1 of them in particular enjoyed many miles of enjoyment and various stages of modifications. It went off the road when its supercharger died (the coating on the rotor edges came off and I think that coating may have munched an internal shaft seal), but at a guess that happened after it had been swallowing 7psi of non-intercooled (IE: quite hot) turbo air for quite a long time.
Quote from: sportiva on June 26, 2016, 06:46:22 AM
When the Busso engine was designed very few production cars had turbos the cam belt de tensioner the head gaskets the synchros the differential none of these components will cope very well. The slow 1st to 2nd gear change will take a second out of 0-60 leave it N/A and less stressed and buy yourself Nissamazota 13btwinblower they are so much better suited to force feeding
I think you're missing the point and at the same time spreading false tales about Alfa's.
First of all, the car is intended to be a
Driver's Car and not a traffic light warrior. The addition of forced induction, if it happens, would also reduce the pure number of gear changes required. Bigger, fatter torque curve and all.
The diff is a concern, tho. 1 idea is to implement a small pump that circulates the transmission oil thru a cooler and then pumps oil directly onto the ring gear and pinion.
I doubt that head gaskets would be an issue. It's the exact same thing for any engine. Don't let it knock, don't over rev it and don't run it lean and you won't brake things. You must have control of the engine to stay on top of all of those things and I'm confident that I have those boxes ticked.
And what does the hydraulic detensioner have to do with forced induction?
If I wanted another Japanese turbo toy I'd buy 1. I still have my supercharged MR2 and an F6 Typhoon.
This thread is intended to get some input from people about what they thought would provide the best driver enjoyment from a 75 Potenziata.
My list of available options are in the first post. Normally aspirated, CENTRIFUGALLY supercharged or twin turbo.
Quote from: sportiva on June 26, 2016, 01:03:48 PM
What suites you top end turbo or lower down torque of a supercharger
This sort of stuff annoys the absolute cr@p out of me! Perpetuating the rubbish that a positive displacement supercharged engine has more low down torque than a well executed (not that the old dinosaur Calloway cars were well executed, but their exhaust manifolds were nice) turbo car.
My supercharged MR2's torque peaked at 4400rpm.
The supercharged VY V6 made it's peak torque (375Nm) at 3000rpm.
My F6 Typhoon's torque (550Nm) peaks at 2000rpm......................... It's held (electronically) to 4250rpm.
Audi, Volvo, Saab and others have also achieved impressive torque numbers at similar low engine speeds.
I realize its hard to fathom (sorry metre)but some of us out there
énjoy light weight natural carby induction
you wont be able to plug in your computer
into these cars in 15 years time
I recently saw a Montreal that had the injection ripped off
and webers put on
and guess which goes better and sounds brilliant?
i would put the carbs on from the euro v6
they are out there and cheap and keep working for 100 years
Mechanical injection from a monty deserves to be ripped off, thrown in the bin and replaced with carbs.
But aftermarket EFI? No way i would ever prefer carbs over a proper EFI setup.
As for the turbo torque Vs blower torque argument, I hear you loud and clear Duk.
The only reason I'd pick the centrifugal over the other three in your conundrum is thus:
When you're pottering around town, changing gears at light load and low rpm, who cares how much grunt it makes? When you want the grunt, it's in the midrange-top end where you expect it.
Off boost fuel economy and drive ability is factory.
As for turbos- why you would go to the effort of building a TT V6 and not running at least 1 bar of boost into it, I have no idea- it's so much effort that your reward should be a whistling, singing engine that boosts hard...nothing comes close, but kiss the transaxle good Bye!
As for the engines not dealing with it- that's absolute rubbish. My old mechanic built a 3.0 12v to take boost AND rev to 8000 and it absolutely loves it.
400rwhp, boost limited to 15psi and rev limited to 4000, heaps and heaps of part throttle grunt... Easy to drive. Gorgeous
So I'm with Dave on this.
Forget the 12v and build a 24v... Modern engine, more top end for less work, and they are more musical than the 3.0 12v.
If you want music and lightweight... 2.5 FTW!
Cheers for your input JulianB.
The reason that I didn't put a 24 valve engine on the list is largly because I want to work with what I've got (engine and parts) and also because, from what I've seen on forums, getting a 24v in a TA car is a lot of work.
Especially if you're working with post 164LS engines, which is what most people would be working with in Aus. And while I could do most or even all of it, I'm not that convinced that it would be worth the effort and expense.
Getting a genuine 300+hp from an internally standard 12v with forced induction is very real. Getting 300hp with a NA 24 valve would take considerable changes to compression ratio, 4 rather expensive camshafts, 4 adjustable cam gears and probably a custom made inlet manifold. (I've left out programmable computer and extractors because they're already part of my plan). And most, if not all gains will be made further up the rev range and probably at the expense of low rpm torque/drivability.
12v engines are A LOT cheaper to work with than 24v engines. However if you have the funds, a warmed up/ boosted 24v would be a lot of fun. Although a lot of funds would be needed to find and fit a stronger transaxle...
Duk I currently have my 12v supercharged Potenziata engine sitting on the stand waiting to be dropped into my GTV6. I'll soon be able to tell you how fun it will be to drive😁 currently has 5pds boost, produces 220rhwp. So should be interesting in the GTV6!
If it were me, in a road car I'd go for a warmed-up NA, and concentrate on weight loss, or at the very least not putting weight on with a force-fed set-up. One of the main issues affecting the handling of a transaxle car is the high weight of the engine (high both in kgs and height).
A race car could probably be made to handle the power from a turbo or supercharger, but you can't do quite as much to a road car if you want it to be driveable, (and I know you've got the handling mods under control). I'm just not sure a 300bhp Transaxle would be that much fun, other than in a straight line, I'm not sure the handling and road holding would cope. And as you say, the transaxle is a little temperamental with big power running through it.
Lower gearing would be nice too (I don't know, does the Potenziata have the same gearing as the 3.0?). I've driven a 3.0 75 and I found the gearing incredibly frustrating, and that it really blunted the driving sensation.
All just my opinions.
And yes, turbos can create great torque figures. Only took me one drive of a rotary turbo to work that out. And my turbo vehicle for work creates 843Nm at 1500rpm......
Hey Sheldon.
Something, which for some reason slipped my mind, after I started the 75 Parts Weight List thread, was that after looking at it, giving it some decent thought and chunching some numbers, I reckoned I could get a genuine 50+Kgs off of the front wheels of my car. Now the car wouldn't necessarily be 50+Kgs lighter as some of the weight was relocated to the rear wheels, but............ ;)
And while that would involve making carbon fiber guards, bonnet and bumper bar, it still retained air conditioning (I mean, it's Australia................ ) and a boot mounted electric power steering pump.
So the thought of adding weight back to the car, especially mounted up high and far forward, does put me off a fair bit.
But then there is the pure grunt factor. And unless you have plenty of engine capacity, getting propper, big fat spread of torque and decent outright power type of grunt requires forced induction.
I'd love a 4 litre interpretation of the Alfa 24 valve engine (would need a 100mm bore and a custom 82mm stroker crank), but unless lots of money lands in my lap, I can't see that happening soon.
Having a slightly mad grunt machine is so very tempting. Probably becuase I'm use to having a reasonable amount of umph under the right foot.
The battle continues.
Come on, you don't need air-con or power-steering, is this car for driving in the hills or for commuting? That's what the F6 is for right? I took the PS off my 90 track car, and it had a 320mm steering wheel, on wide slicks; definitely a pain in the arse to park, but how often do you do that? Made no difference to driving over 10km/h. Okay, maybe 30...
Don't forget, if you were to force-feed her, you'd probably need a bigger radiator as well, adding weight to the worst possible place.
I know what you mean, grunt can certainly be addictive, but I'd go for handling with just enough horsepower, over an overpowered car every time. Grunt is good in short bursts, but handling is forever.
Yeah, I've often thought myself about how a 4 litre would have been, with a TA that could cope with it. The 3.0, and even the 2.5, was considered a 'big' engine in the 90 and 75 in period, but times have certainly changed. I look with envy at every Mercedes C63 I see.
The TA cars are really well balanced, and reasonably light, so I always figured I'd enhance those characteristics, rather than trying to make them into something they're never going to be.
Something that I've occasionally thought about to help the handling, but wouldn't have the skills to do myself, is to lower the engine in the frame. Don't even know if it would be possible, but you clearly have some skills and knowledge. Trouble with that is that it would have to be dry-sumped in all likelihood. That, and get the biggest tyre footprint you can.
Again, just my opinions, I know FA.
So given all that, you should "just" put together a twinspark with say 20lb boost, plenty of space for aircon and PS and a big snail doesn't weigh much :)
Quote from: Sheldon McIntosh on July 23, 2016, 08:35:42 PM
Come on, you don't need air-con or power-steering, is this car for driving in the hills or for commuting? That's what the F6 is for right? I took the PS off my 90 track car, and it had a 320mm steering wheel, on wide slicks; definitely a pain in the arse to park, but how often do you do that? Made no difference to driving over 10km/h. Okay, maybe 30...
Don't forget, if you were to force-feed her, you'd probably need a bigger radiator as well, adding weight to the worst possible place.
I know what you mean, grunt can certainly be addictive, but I'd go for handling with just enough horsepower, over an overpowered car every time. Grunt is good in short bursts, but handling is forever.
Yeah, I've often thought myself about how a 4 litre would have been, with a TA that could cope with it. The 3.0, and even the 2.5, was considered a 'big' engine in the 90 and 75 in period, but times have certainly changed. I look with envy at every Mercedes C63 I see.
The TA cars are really well balanced, and reasonably light, so I always figured I'd enhance those characteristics, rather than trying to make them into something they're never going to be.
Something that I've occasionally thought about to help the handling, but wouldn't have the skills to do myself, is to lower the engine in the frame. Don't even know if it would be possible, but you clearly have some skills and knowledge. Trouble with that is that it would have to be dry-sumped in all likelihood. That, and get the biggest tyre footprint you can.
Again, just my opinions, I know FA.
Lowering the engine and moving it back are well worth considering. Doing it for a decent price is the challenge.
Maximising tyre footprint is on the cards with some extra mods.
Me being a Family man I opted with my last car a Proton Satria GTi and now with an Alfasud I opted for light weight and handling. Not had the Sud for all that long but it was already used for Targa's and Hill Climbs so it was no brainer to purchase it when a Roo took out the Satria last December. I removed over 130kg from the Satria and improved the Exhaust along with fitting a 1.4kg Flywheel plus a lot of other stuff. But the GTi handles like 'corner what corner'. Before purchasing the Sud I did the last 6 stages of Targa Tasmania 2016 and was very impressed with what it did to higher powered cars like Porsches, Evo's, Wrx's and a Nissan GTR. Admittedly the 1600 Sud puts out 145hp at the wheels so it's no slouch but it was in the corners where we made up our ground on the other cars plus the driver wasn't scared to cut the corners and drive on the grass to shorten the track or Stage. Suspension was just worn Koni's with front Alf Struts. The GTi had C/O's etc etc with an internally stock engine and netted me 3rd in Class B the first year and 2nd last year in Class B (State Hill Climb Series in Tassie. It was always around the top ten outright or just outside it. So in my opinion one doesn't always need tons of power but the guy in the Honda that always won Class B has a stack of money in the engine and computer. I wanted a car that's well balanced and easy to drive on the limit. I admit there is a litle sorting and up grading with the Sud but even thou the Sud has won lots of Class races and quite a few times outright. The Proton was tons of fun and predictable on the limit and I left the AC connected and used it to clear the glass plus it was a bonus on hot days.
Some nice input Trikes.
Getting the 75's weight down and improving the location of key parts is high on the 'want' list.
But as I've mentioned, having some stout grunt without having to rev the crap out of the thing to achieve decent performance is also high on the 'want' list.
If I could mount the Vortech to the clutch housing and drive it off the tailshaft...................... :P :P :P
I'm with Duk on the carbs reliability question. I spent 30 years or more playing with carby engines in VWs, Alfa 33s and others and wouldn't go back to them after getting used to EFI. Carbs suffer from worn linkages, accelerator pump wear, blocked jets, leaking gaskets and not staying in tune to name a few things. I was always having to fiddle with mine. They rarely run completely smoothly, unless brand new and tuned perfectly and even then, not for long. Even at 20 plus years old the old L-jet is very reliable and smooth. The Motronic system is even better. Both benefit from reconditioned injectors after many years of trouble free operation. Once you understand EFI, it is easy to maintain and you very rarely have to touch a thing. If anything does play up, it will most likely be an easily replaced sensor.
We have two L-Jet 3 litre 75s at present, along with my 2004 GT with the glorious 3.2 Busso and my wife's 159 2.4 JTDM ti wagon and we love them all. I also owned two Potenziatas previously and two 164s. My preference is for putting a 3.2 in the 75 one day. My GT has bags of power with that typical Busso flat torque curve, revs easily to 7,000 rpm and is incredibly flexible. It will start off in 2nd without blinking and even in 3rd if you ride the clutch a bit and as a result is a joy to drive in any conditions. I always thought the old 3 litre 12 valves were flexible, but the 3.2 is more so. It will drive around like an auto with your foot off the throttle easily. Mine has a cat-back exhaust system and sounds absolutely awesome. The 2.4 diesel is a lot of fun to drive too. It has 400nm of torque and 210 bhp, gets off the line very quickly and flattens hills like they aren't there. I have no problem with the reliability of turbos on an engine designed from scratch with them and like the power they give, but they are way outside my budget, skill and patience to fit to a non-turbo engine like the old Busso 12 valve.
Something that carby owner/flag wavers always seem to be completely ignorant of is the fact that a carby, or mechanical injection for that matter, simply can't be accurate over the hugely varying operating conditions a road car engine is expected to operate in.
Plus there is the problem of how carbies actually work, especially when idling.
When tiny amounts of fuel are expected to be drawn out of the carby and into a small amount of slow moving air and maybe having to cover a reasonable distance, fuel falling out of what little air movement there is, is very real.
The notion of carbies being accurate and efficient is purely rediculous.
Yes, if sized and tuned correctly a carby(ies) more can deliver the correct amount of fuel and present no significant flow restriction when the engine is operating at peak power. In the same way that a mechanical advance distributor can also provide the correct ignition timing that the engine needs at peak power (or peak torque, but chances are not both). But that is a very narrow operating condition and 1 that is rarely used in a genuine road car.
Expecting a carby or 2 and a purely mechanical type distributor to be able to accurately deliver fuel and correct ignition timing in a force fed engine is even more rediculous.
And I haven't even mentione temperature compensations. Which are hugely important for correct and accurate running in the real world and even more so with force fed engines.
Tuning.................
Changing numbers on a computer screen and seeing the effect of those changes on a wideband air fuel ratio meter is MUCH easier than piss farting around with jets and emulsion tubes. The computer can deliver pretty much any injector open time within the available time frame. How many different jets and tubes do you have available to try and see what happens?
I have a couple of good books on tuning Weber carbies and from I recall, figuring out the Italian logic and the effect of emulsion tubes is more art than science.
Similar for ignition timing mapping. But that is more the domain of the dyno and having extra ears attached to the engine to listen for knock is a priority, especially if the engine is likely to octane limited in its ability to take high load ignition advance.
Ignition timing!
Nothing has more potential for damage, drivability problems and compromised power than incorrect ignition timing.
How on earth do people think they can provide the engine with the best ignition timing that the engine needs under any operating condition with a purely mechanical device???
Simple, you can't. So pretty much every aspect of the ignition timing will be compromised.
Again, temperature compensations are very important.
You can not tune a carby/mechanical advance distributor for something that it simply can't do.
It's like expecting a programmable computer to do something like control continuously variable valve timing when the makers of the system never implemented any means of doing so. You can't use and apply what isn't there.
I like Italian carbies too. But this is what's left of 2016 and I have a good quality programmable computer...............
The Motronic isn't worth squat in these cars. Alfa must have used the cheapest and nastiest version of the system they could. Too many compromises to make any effort to tune it to suit half resonable changes wasted time and money.
And I still don't know what to do with my 75. :o
(http://s2.quickmeme.com/img/00/00c1fa6714a2d4b639e996bd9294ec27e1213bff1de4958492aaf1a16ae5f3a7.jpg)
Quote from: jazig.k on December 16, 2016, 02:30:59 PM
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Into your 7 Series??? Nah man, the LS1 are a seriously over rated engine! ;D ;D ;D ;D
Quote from: Duk on December 16, 2016, 12:49:25 PM
And I still don't know what to do with my 75. :o
Put the poor thing back together and drive it while you think about it.
Quote from: oz3litre on December 16, 2016, 02:46:36 PM
Quote from: Duk on December 16, 2016, 12:49:25 PM
And I still don't know what to do with my 75. :o
Put the poor thing back together and drive it while you think about it.
(https://cdn.meme.am/cache/instances/folder298/32454298.jpg)
Quote from: oz3litre on December 16, 2016, 02:46:36 PM
Put the poor thing back together and drive it while you think about it.
Ahhhhhhhhhhh, No.
Well, kinda............. Maybe............
To me there aren't many things that are worse than rework. Doing things more than once is both painful and expensive. And I've potentially already done a few.
'IF' I can settle on a plan, I believe I have a suitable map for any of them listed in the first post.
Someone from some part of the world has even posted on GTV6.com recently, a decent solution to gain some transaxle durability.
Where I still struggle is in the badly located additional weight of the force fed engine variants VS the negative effects that weight is expected to have on the handling characteristics of the car VS my basic desire to have a very grunty and basically lazy torque monster of an engine...................
Read: I have had 2 big fat torque curve engined cars now and it's a hard habit to kick!
Appart from the additional weight issues of adding forced induction, 2 other problems nag at me.
The brakes and the definative decision of either a modified normally aspirated or (standardish engine) force fed!
I know I've ranted in the past about the brakes, but the more I think about the car's braking (and tyre!) capacity, the more I see it needs to be increased.
I created my inboard rear brake upgrade based on Series 4/5 RX7 Turbo calipers working on Wilwood vented rotors. And I'm sure if completed they would work well. They're a large diameter vented rotor and the calipers have MUCH more pad surface area.
And the handbrake mechanism isn't Italian.................... :o
But those rear brakes and the old Volvo 4 piston caliper/164 rotor front brakes do start to look a bit feable when you start to compare them to similar weight cars with similar (potential, force fed) target power.
Think R32 GTR and Evo 6 onwards Lancers as a starting point.
The other problem is that of a modified normally aspirated VS forced induction.
If I went with an NA engine arrangement, then I'd be having the heads machined to bump up the compression ratio.
But obviously if I wanted to go with a force fed solution, keeping the compression ratio down around standard would be the best compromise I can make.
But because you have to take the engine out to remove the passenger side cylinder head, I'm not going to put the engine back together and reinstal it in the car just to figure out what I want to do. Engine removal, another pair of head gaskets and cylinder head machining after the fact is too painful.
It may not come accross the way it should, but I am genuinely thankful for you guys who participate in my mental wanderings. Extra info does actually help me sift thru my own mad scientist thoughts a bit more.
To add insult to injury, the Dr. Frankenstein ideas that I have for the front suspension and chassis should, in theory, help offset the potential negative influence on the balance/handling characteristics of badly located added weight of any forced induction.
It's all good fun thinking about these things and learning from others. The biggest problem for my son and I with the project black 75 is money to do mods with, so we are gradually doing things and driving the car in the meantime. It has come a long way since we bought it in undrivable condition, that's for sure. It now has a nice set of 17" wheels and tyres that have made a big difference to the drivability and appearance. The interior is coming along with the leather GT front seats, new carpet, reupholstered rear seat, Momo pedals, leather handbrake and gearshift boots and stuff. The next thing is to get new headlining put in and a decent set of front door trims. The engine runs beautifully, having been serviced by our Alfa mechanic all of its life bar one year and being a low mileage example. It is one of those engines that comes out of the factory a bit better than its peers I think. Engine swapping or big power mods are a fair way down the track at this stage. In the meantime, the red 75 needs the spare clutch kit fitted. It has been sitting for two years waiting for that. I have to dismantle the thrust bearing on the replacement clutch to lubricate it first. My son intends to keep that car as a stock example because it is in such good nick. The black one is the test bed for mods.
The more I think about this, the more I think that being able to add engine capacity and build a stout NA engine would be the best combination of performance, tractability and chassis balance.
I even started to mentally nut out an inlet manifold design with dual length runners and joined/separated dual plenum chambers (it's a 60* V6 and being able to join and separate the 2 halves of the engine should yeild improvements in the engines torque curve, especially when you have agressive camshafts that let you chase top end power).
But the big bore kits that are available are just so flippin' expensive!
2500Euros, plus freight, plus tax, plus block machining.
I started looking at the viability of finding semi-suitable sleeves and pistons from other engines.
The air cooled Porsche 3.6 litre engines use 100mm bores (not the 101mm bore the 3.5 kits use) and 2 valve per cylinder hemispherical combustion chambers. The bigger bore cylinders have their cooling fins as part of bore. So the bores are the Nicasil treated aluminium sleeves.
Then there are the custom made head gaskets.
So I pretty much thru that idea in the bin.
But re-reading some threads on GTV6.com says that the big bore kits don't exactly have a good reputation for reliability. Now some of the comments were going back a few years, but I think there may be an underlying challenge and that basically comes down to accuracy.
Really speaking, the sleeves should be machined from a single block of (suitable grade) cast iron rather than have individual sleeves. Then the block should be more rigid and the new bottom end could be accurately bored and honed to correct size and tolerance with actual torque plates bolted to the engine while it's attached to a crank tunnel fixture............... :o
I have also heard of reliability issues with the big bore engines. A guy in Holland had one in his SZ and got sick of the problems and ended up putting a 3.2 in it. I am having trouble picturing how your idea of having liners machined from a single block would work. Can you elaborate further on that? It sounds interesting.
The best and most dramatic examples are from the NORD and TS engine block.
Grabbed from: http://www.autocomponenti.com/projects/two_new_records.htm I should have named it monosleeve.
Thanks. Now I get what you mean. I have seen those before. That looks like it would be an expensive process to make though.
I've not seen 1 for the V6 engines, but me thinks it would be a much better way to go about creating a big bore version of the engine.
Weiredly enough, I have absolutely no idea how and where people get slabs of metal like that.
I only work at a steel works, but in the past when special bits of metal are needed for the machinists to make something, that stuff just appears like magic. ???
Just purely for the sake of it, does anyone know of a suitable grade of steel that cylinder liners could be made from?
Nearly all cylinder liners are made from some type of iron and for good reason. But a couple of slab of suitable iron would be rather difficult to find.
The other option would be to follow in Porsches foot steps and make a monosleeve from a suitable grade of aluminium and have the bores Nicasil treated after final machining.
Quote from: Duk on December 16, 2016, 12:49:25 PM
Plus there is the problem of how carbies actually work, especially when idling.
When tiny amounts of fuel are expected to be drawn out of the carby and into a small amount of slow moving air and maybe having to cover a reasonable distance, fuel falling out of what little air movement there is, is very real.
The notion of carbies being accurate and efficient is purely rediculous.
Yes, if sized and tuned correctly a carby(ies) more can deliver the correct amount of fuel and present no significant flow restriction when the engine is operating at peak power. In the same way that a mechanical advance distributor can also provide the correct ignition timing that the engine needs at peak power (or peak torque, but chances are not both). But that is a very narrow operating condition and 1 that is rarely used in a genuine road car.
Expecting a carby or 2 and a purely mechanical type distributor to be able to accurately deliver fuel and correct ignition timing in a force fed engine is even more rediculous.
I agree that carbies can't do the fine matching to just about any situation that EFI can (not the L-Jet with no feed-back). What always amazed me was the lengths that some carbies went too - such as in Rotaries with their 4-throat, dual stage Niki's with dash-pots, vacuum actuators & mechanical throttle links & other gubbins all over the place. And I love what the Gregories manual said about any problems in the carby on the '89 corolla: "Very well made precision device. Forget trying to fix it - replace it" - or words to that effect.
Keep working on this discussion people. I've sold my house to down-size, the wife has stated as one of the requirements for the new place is "A Garage for you, to get you out of my hair". I plan to have some cash for another play-thing car and have looked at all the options butI keep coming back to the GTV6 - but I can't decide on the engine.
To be able to match the power to weight ratio of my big fat F6 (1720kg) in the Alfa, the full weight (1350kg) car would need 284hp.
If 50kgs could be dumped from her, the power required would be 273.
And down to 1250kgs, 262hp.
Getting the car's weight down by 100kgs would be a big challenge. Especially as keeping air conditioning and power steering is a must (well, maaaaaaybe the PS could go).
Getting 260hp from a normally aspirated 12 valve is doable (if Richard Jemmison's claims are anything to go by).
But it would be impossible to match the pure spread of torque that the F6 can dish out, unless going for forced induction. And even then the centrifugal supercharger is not the right choice and the Taxi has dual continuously variable valve timing.
To give an idea about trying to match the torque to weight of the F6. Even if the Alfa was down to 1250kgs @ 2000rpm it would still need to dish out 400Nm of oomph.
Or 57.5%/170Nm more torque @ 2000rpm than standard. :o
Come on Duk.....It's good to have a dream.
Regards
Steve
Adelaide.
ITT - Why the F6 is better and I won't ever finish the Alfa.
Fitting a 100mm, 101mm or 103mm big bore kit would not mean re-inventing the wheel and probably give you the torque you want. The horsepower and long term reliability might be an expensive challenge however!
Having played around with race kart engines for while their certainly are engineering issues to be resolved with regard to fitting bigger cylinders / liners into an existing block of alloy. The mechanical challenge of dealing with cavitation and resultant erosion of wet liners up near the combustion chamber is one thing as is the thermodynamic challenge of conducting away all that additional heat absorbed into the greater surface area of the larger diameter bores.
Given the 3.2 JTS engine is based on a RWD / North South powered car could the GMH / Holden sourced block be rotated 90 degrees and dropped into the chassis? In standard tune it puts out 260 HP and loads of torque thanks to it direct injection. With no CATS and a bit of re-mapping 280 < 290 HP should be achievable. Plus the engine is about 160kg.
All with standard and very easy to source bits! The 3.2 JTS in a car 300kg lighter than a 159 might be something!!!
Quote from: jazig.k on December 22, 2016, 09:16:12 AM
ITT - Why the F6 is better and I won't ever finish the Alfa.
It's about time you acknowledge the superiority of the F6. :P
As for finishing the Alfa, yeah I have a pretty bad track record with it, but I will finish it when I settle on a plan.
Quote from: Colin Edwards on December 22, 2016, 12:33:10 PM
Fitting a 100mm, 101mm or 103mm big bore kit would not mean re-inventing the wheel and probably give you the torque you want. The horsepower and long term reliability might be an expensive challenge however!
Having played around with race kart engines for while their certainly are engineering issues to be resolved with regard to fitting bigger cylinders / liners into an existing block of alloy. The mechanical challenge of dealing with cavitation and resultant erosion of wet liners up near the combustion chamber is one thing as is the thermodynamic challenge of conducting away all that additional heat absorbed into the greater surface area of the larger diameter bores.
Given the 3.2 JTS engine is based on a RWD / North South powered car could the GMH / Holden sourced block be rotated 90 degrees and dropped into the chassis? In standard tune it puts out 260 HP and loads of torque thanks to it direct injection. With no CATS and a bit of re-mapping 280 < 290 HP should be achievable. Plus the engine is about 160kg.
All with standard and very easy to source bits! The 3.2 JTS in a car 300kg lighter than a 159 might be something!!!
There won't be any engine conversions.
Even if I did entertain the idea, I would just use a Commodore 3.6 engine.
Twin compound turbo with supercharger setup.
Quote from: jazig.k on December 22, 2016, 10:41:37 PM
Twin compound turbo with supercharger setup.
On a 7 litre LS?
With nitros?
And a 2 speed Powergluide?
I was doing some rough number crunching and added up some guesstimated weight reduction figures.
They were all guesses, but with a bunch of carbon fiber panels (bonnet, boot lid, front guards, front and rear bumpers) and tailshaft, fabricated suspension arms, coil springs instead of torsion bars, no power steering, no brake booster and cross over, even things like the fabricated extractors, I guessed about 75-80kg of weight removal.
But that didn't allow for the new cabling for the boot mounted battery, the chassis reinforcement, the bigger brakes or the larger exhaust. The Volvo calipers will be replaced with 4 piston RX7 calipers.