Alfa Romeo Owners Club of Australia Forum

State Divisions => New South Wales => Topic started by: Angellino on July 17, 2020, 03:30:28 PM

Title: Engine Conversion from 1750 to 2000lt
Post by: Angellino on July 17, 2020, 03:30:28 PM
Hi Crew, have recently purchased a 1970 1750 105 and would like to work out if its easy to convert a 1750 to a 2000lt?
Is it worth converting or would you buy a used 2000lt from ebay and start again?
Currently the car has matching engine numbers and would like to keep like this but also gain performance hence converting internals to 2000lt.

While on the subject is the 1750 (1970 model) gearbox same as the 2000lt gearbox or would this need replacing?

Your advice and suggestions would be valued and appreciated.
Title: Re: Engine Conversion from 1750 to 2000lt
Post by: giulia_veloce on July 18, 2020, 06:56:28 AM
All depends on Budget.
Just buy a Complete 2 litre engine
Fitting a 2 litre engine is the same as a 1750.
no difference in fitting.
Gearbox is the same.
Everything else is the same.
Get a Complete engine with Carbys,starter motor,Flywheel,as these are different.
8 bolt flywheel for a 1750 vs 6 bolt for 2 litre
8 tooth starter motor 1750 vs 9 tooth  for 2 litre.
Clutches are the same.
Exhaust is the same.

I guess its all got to do with the car.
if its a Good car,,leave it 1750.
If your choice is a 2 litre engine,,just do it.
Title: Re: Engine Conversion from 1750 to 2000lt
Post by: MD on July 18, 2020, 07:19:42 AM
When you have just acquired a car, it is not generally considered that you may want to sell that car in the future. One gets caught up in the gunna do dis and maybe gunna do dat syndrome. I know I have.. :)
The point of this advice is that it is exactly how you should view the project if final value is something that is of interest. If it is not then modify to your heart's content. If it is, then keeping the car authentic and original brings the best returns for your investment which means rebuild the 1750 engine.
More power may mean less resale value. Your call.
Title: Re: Engine Conversion from 1750 to 2000lt
Post by: bonno on July 18, 2020, 09:58:09 AM
Welcome aboard Angellino and totally agree with the replies above. Having a matching numbers car is highly desirable for resale value and the difference in HP for street use would be marginal. A set of tuned extractors, port and polished head, rejetting of carbs, electronic distributor  and mild street cams would be sufficient to increase power of around 30%.
bonno   
Title: Re: Engine Conversion from 1750 to 2000lt
Post by: Angellino on July 18, 2020, 02:59:41 PM
Thanks guy's I feel the love, very wise words from all responses, much appreciated.

What if I keep the engine stored away and then do something crazy like twin spark with carbs does that also detract from the value?

Could offer the original 'matching numbers' engine if I were to resell?

Car is reasonable, like everything this age needs some loving but generally drives well, lots of leaks, inc. carbies, previous owner had for 14 years I think and never opened engine.

So hence one school of thought was to keep car going build second engine, store away original and have lots of fun?

Like many seduced by the alcoholics post, and I'm sure car would be wild with 180hp?
Title: Re: Engine Conversion from 1750 to 2000lt
Post by: MD on July 18, 2020, 03:29:07 PM
Angellino,

From your last post is clear that you need to develop the vision for this car.
Without a clear vision, it is a bit like being a little bit pregnant. A conundrum.
Remember that a modified street car will never deliver performance of a race car and a race car will never perform like a street car should. Everything in between is usually a money pit and winds up being a huge magnet of infringement fines.
Stay focused. Keep the vision within your budget which usually evolves to be an upside down triangle. Deliver a conclusion.

Best of luck. ;)
Title: Re: Engine Conversion from 1750 to 2000lt
Post by: Craig_m67 on July 19, 2020, 11:38:37 AM
Personally I donít put much value in number matching Alfaís... thatís just me though, others do.

That said, how do you know itís a numbers matching original car?  Those that do care about these things will want some sort of original paperwork that shows the engine number/rego/chassis etc from new (or very early).   Alfa will not tell you the correct or original engine number, although itís been said they will confirm if you let them know what you have?

The best 105 is one that has no (more) rust.

Engine types come and go but I really donít think anybody is going to devalue a car because it has a twinspark conversion (especially given its revertable)
Title: Re: Engine Conversion from 1750 to 2000lt
Post by: bazzbazz on July 19, 2020, 01:54:17 PM
The best 105 is one that has no (more) rust.

Is that even possible?   ???

  ;D ;D ;D
Title: Re: Engine Conversion from 1750 to 2000lt
Post by: sportiva on July 19, 2020, 06:17:48 PM
I would have a rusty Alfa Romeo with twin carbies points and plugs before any Fiat Romeo.
Alfa Romeo 1.3 1.6 and 1750 engines had the same bore spacings. The 2.0litre has a wider spacing between cylinder 2 and 3. The outside diamensions of all the engines are the same so fitting a 2000
engine into a 1750 chassis is not an issue
Title: Re: Engine Conversion from 1750 to 2000lt
Post by: Angellino on July 20, 2020, 12:21:02 PM
Thanks for all the love guy's was driving the nuts off the car on the weekend and recon only needs to have an extra 30 - 40hp, I reckon if I could get 150hp out of the 1750 and have it sound good I don't think it needs much else.

We checked the casting symbols on the head and numbers on block and engine in definitely a 1750. It also currently has new stainless race headers and alcoholics muffler.

Thinking of speaking to a couple of engine guy's to see what 150hp mojo would cost. Lots of talk about PACE engineering in the literature. Anyone had experience with PACE or getting stuff from them? Any special Sydney engine guy's with big Kahoona's for special Nord engine builds you guys recommend.

Overall the car was so much fun, really enjoying it, not planning to take on track but if I did it would be for the smiles not for race. So if matching numbers which we presume it is and believe 150hp would be plenty maybe the 1750 engine can be tweaked to achieve this?

Thanks for all the attention and love my fellow Alfisti, cheers
Title: Re: Engine Conversion from 1750 to 2000lt
Post by: Colin Edwards on July 20, 2020, 01:15:47 PM
Hi Angellino,

Given a "stock" 1750 has a published output of 120HP, a 25% increase to 150HP may be a tad ambitious for a "road tuned" 1750cc 8 valve engine on carburettors.
Have you had the car on a dyno yet?  What's it putting out at the rear wheels?  A bit of reverse engineering from chassis dyno figures should indicate likely engine output.
Maybe the present engine needs a bit of love.  Maybe the present engine is only developing 100HP < 110HP? 
Could a full rebuild / blueprint / balance realise 125HP < 130HP?
Does the car at present feature truly effective cold air input to the engine?
Looked at lightening the car?
Jim Kartalamakis published a book some time ago on the subject of tuning Alfa Romeo Twin Cam engines.  Its not a bad read!

Vin Sharpe at PACE is a bit of a wizard with these engines and definitely worth talking to before opening your wallet!

Colin

Title: Re: Engine Conversion from 1750 to 2000lt
Post by: Angellino on July 20, 2020, 02:18:02 PM
Hi Colin,

Thanks for this, the figure I got for the 150HP was from Jim Kartalamakis published a book.

Has anyone tested this? This was assuming doing the heads fully ported, balanced etc. hot cams, HP pistons and race style headers, still maintained the webber's.

Interested if anyone has been able to get the 150 claimed by Kartalamakis for a 1750 with the above?
Title: Re: Engine Conversion from 1750 to 2000lt
Post by: bonno on July 20, 2020, 03:38:49 PM
Hi Angellino
There has been great debate on the subject of performance gains of the 1750/2000 Litre Nord engines, as well as several books written on the subject. For the sake of not reinventing the wheel, I have attached a link to the ALFAbb for your information.
https://www.alfabb.com/threads/performance-upgrades-for-1750-2000.113653/
Title: Re: Engine Conversion from 1750 to 2000lt
Post by: Angellino on July 20, 2020, 03:55:45 PM
Thanks Bono, will definitely read through, looks like lots of valuable info, many thanks, appreciated.

Cheers
Title: Re: Engine Conversion from 1750 to 2000lt
Post by: Craig_m67 on July 20, 2020, 05:54:57 PM
Fastest, cheapest, easiest and most reliable way to get that power is stick in a Twinspark from a 75 (155/164). ie. a ^NORD twinspark which is the last iteration of the engine you have.

Pretty much just bolts in (2L flywheel, spigot bush, other stuff..)

.... then, once you want more again you can fettle it with carbs/throttle bodies/3D mapping.. etc., yada yada.


(^Not to be confused with the twinspark/JTS engines in the 156/147 etc... completely different animal)
Title: Re: Engine Conversion from 1750 to 2000lt
Post by: Colin Edwards on July 22, 2020, 10:00:51 AM
The Alfa Twin Spark is certainly an "improvement" of the earlier design.  A further reinforcement from Alfa Romeo that less is more!
Producing around 10% more power with lower emissions, probably due to the improved combustion efficiency, Alfa held true to their philosophical approach to performance.
Using the equation Output (power) = input x efficiency, Alfa increased efficiency.  For a given input, output MUST increase when efficiency is improved.  This is undeniable as is the maths behind this simple equation.

As little as 20 years ago, TAFE colleges were teaching the best IC engines / Otto cycle engines were no more than around 25% thermally efficient.  One half of the remaining heat went into the coolant and the other remaining half out the exhaust.  Its ironic that most aftermarket "tuning" focusses on simply increasing the input to the engine.  A very unenlightened and out of date approach.

Any measure that will reduce the combustion heat (energy) absorbed into the water jacket must improve efficiency so therefore must improve power output. 
Any measure that will reduce the combustion heat (energy) released into the exhaust must improve efficiency so therefore must improve power output.

Some of these measures are very simple to apply and some not so simple.  Just need to consider the old Otto IC engine as a "system" or "process".  The same philosophy applies to any machine "tuning". 

Big carbies, big ports, big valves and big cam lobes will increase input but do nothing for thermal efficiency. 

TAFE Colleges and most text books used to say it was impossible to ignite an air / fuel ratio greater than around 14:1.  I understand the twin spark can ignite 16:1 under certain conditions.  Present F1 engines have no problem with 20:1 and are more than 50% thermally efficient. 

Reduce waste, reduce losses, improve combustion efficiency.  An increase in output / power for a given input must be the result.  We cannot argue against the equation.
Title: Re: Engine Conversion from 1750 to 2000lt
Post by: Ascari32 on September 01, 2020, 04:30:47 PM
I would have a rusty Alfa Romeo with twin carbies points and plugs before any Fiat Romeo.
Alfa Romeo 1.3 1.6 and 1750 engines had the same bore spacings. The 2.0litre has a wider spacing between cylinder 2 and 3. The outside diamensions of all the engines are the same so fitting a 2000
engine into a 1750 chassis is not an issue

Agree. I have owned from new 1750's and 2000's and I view the 1750 as the better engine. Silky smooth, revs its nut off. The 2 litres have more grunt, but you pay for it with a degree of coarseness the 1750 does not have. A Balanced 1750 with Colombo Bariani Camshafts is a thing of beauty. preferably with Dellortos. But even in standard guise is delightfully balanced.

Had a 156, 1.8 (1750) in later years and it too had a better balance to it than the 2 litre version. In a way, very similar to the difference between the 2.5 Busso and the 3.0, 3.2 Busso's. I would kill to have my old GTV6 Alfetta back! I have a very low mileage 3.0, 916 and as much as I love it, it's an affair, not a life long passion. The 2.5 too was balanced and fitted with C.B.s and on the Auto Routes in France, nothing could live with it.
Title: Re: Engine Conversion from 1750 to 2000lt
Post by: GG105 on September 11, 2020, 08:52:21 PM
Really hard to know how to respond to threads like this.

I have a 1300Ti with a warm two litre in it. It was in it when I bought it nearly 30 years ago. It has the usual stuff, higher comp, ported head, extractors, electronic ignition, etc, produces around 150+hp depending on the dyno you use. It also has very careful and effective suspension mods not including the Alfaholics lowered nonsense. It looks quite stock, but isnít. I also have a fairly standard stepnose 1600 coupe.

The result is a quick car - for 1970. Its drives really well, very comfortable and capable in modern traffic, it feels and sounds great but its not a fast car anymore. I also have a 997 Porsche Turbo with 480hp, 500hp with overboost. This is a fast car.

So what is a 105 series Alfa in 2020? Its a vintage car. Itís also probably the best driving car of the 1960s, no small achievement. What they offer is a level of feel and communication modern cars no longer have. If you donít lower them too much and stick with skinny wheels you get to experience the essence of them and the genius of the engineering.

If you heavily modify them you donít really get a fast car and you lose a lot of what makes them special. To me its about respect, but, hey, each to their own.



Title: Re: Engine Conversion from 1750 to 2000lt
Post by: Ascari32 on September 13, 2020, 01:26:17 AM
I share your view. In modern terms, of course they can't compete. But there are very few modern cars that give the driver as much as these little jewels. There is a connection between the chassis/body and the mechanicals that define these cars like no other. That is what makes them so special. They are greater than the sum of the parts. Modify them too much and they become less.

I had a fantastic day on the track with a Lambo LP640, a Nissan GT and a 430 Ferrari as a birthday gift. The Lambo was utterly brilliant because it demands so much from the driver/pilot. Basically, it wants to kill you. The GT was anodyne - it wouldn't let you kill yourself. And the Ferrari, just a lovely place to be - behind the wheel.

The Lambo stands out for what it can do. But, beyond that, I couldn't live with it for too long. Performance is great, if one has the ability to exploit it and I do not. But a Bertie, a Berlina, an Alfetta GTV6 or a Spider 2000 - well they were made with people like me in mind.

They also had an incredible gift of persuading me I was in charge - that I actually could drive them well!