Author Topic: Engine Conversion from 1750 to 2000lt  (Read 1687 times)

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Colin Edwards

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Re: Engine Conversion from 1750 to 2000lt
« Reply #15 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  A very unenlightened and out of date approach.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.
Present
2018 Abarth 124 Spider
2015 Giulietta QV (2020 Giulietta Veloce on the way)
1987 75 3.0

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2012 Giulietta TCT Veloce
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1979 Alfasud Ti 1.5

Ascari32

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Re: Engine Conversion from 1750 to 2000lt
« Reply #16 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.

GG105

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Re: Engine Conversion from 1750 to 2000lt
« Reply #17 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.



1961 Giulietta Sprint
1969 GT 1300 Junior
1970 Giulia 1300 TI
1984 SA GTV6
1963 Ford Falcon Futura Convertible
1990 Mazda MX5
2005 BMW 330Ci
2007 Porsche Turbo

Ascari32

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Re: Engine Conversion from 1750 to 2000lt
« Reply #18 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!