Author Topic: Engine Conversion from 1750 to 2000lt  (Read 692 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  A very unenlightened and out of date approach.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

Past
2009 159 3.2 Ti Q4
2012 Giulietta TCT Veloce
2006 147 Ti 2 door Selespeed
1979 Alfasud Ti 1.5