The theory behind performance increase

The performance of an engine directly depends on the amount of mixture that goes through / is burned and is transferred into mechanical energy per unit time.

To increase performance, there are 3 possibilities:

• A: Optimize combustion
• B: Improve the mechanical efficiency
• C: Increase the amount of mixture put through per unit time, and with it the volumetric efficiency.

Which possibilities can be achieved following these physical ground rules?

Possibility A can only be done up to a point since the engine constructor has set most parameters.
Possibility B can not be done without making big changes and many long dyno tests.
Possiblitly C is the normal way to achieve this goal.

Possibility C gives another 3 options:

1. Displacement can not be replaced by anything, except yet more displacement!
   (If a little is good, more is better, too much is perfect, Yankee saying)
2. With longer camshaft duration. This has it's limits, and these are easily found.
3. By increasing rpm. This "costs little" and "weighs nothing" but sooner or later it takes it's toll...

What good is an engine that wakes up at 6000 rpm and dies off at 8000 rpm? Surely this is no fun during daily driving. And how are you going to get up the sidewalk at night without waking up the whole neighbourhood?

A usefull combination of all given options give a "smart" solution.

Here is a summation of options:

• Standard 2 CV 6 engine: optimal carburetor jetting, compression 9:1 or 10:1 (Special pistons and barrels).
• Like previous, but with 650 or 660cc (98 leadfree or 95 leadfree).
• Like previous, but including modified camshaft.
• ST70P engine, 720cc and special camshaft.
• Twin carburetors.

This includes most possibilities.

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