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Gas entering the chamber is controled by ECU/injectors/timing curve on cams. Unless your timing is really buggared, Tino's implication that you are allowing more time for fuel to enter the chamber is not entirely correct. If you were timed to ignite significantly before all the gas entered the cylinder you would have flames entering the manifold as the valves would be open. You gain or lose some HP by changing WHERE you ignite the mixture in the cylinder along the pistons' path. You get less "push" with incorrect timing despite the same amount of mixture. (less bang so less RPM). Also, it takes time for mixture to burn, so you time your spark to allow the explosion to propogate down to the piston at the right time.
Advance is important. Why else would you have a vacuum advance on your distributer/engine that advances timing as the RPM increases? Deactivate it, and see what happens. It won't hurt the car, but you will see you lose HP for a given RPM. The key is not too much and not too little advance, as I initially stated.
Tino seems to imply that he is running richer due to his stock setup with 3bar FPR. From my understanding in conversations with JAK and my mechanics and my manuals, you do not run richer with a larger FPR unless you are at WOT. If not at WOT, the ECU senses how much gas the car gets and just backs off the injectors to compensate for the increased pressure at the rail. The injectors spend less time open, and the engine gets the same amount of fuel. You would need to reprogram the ECU for the 3 bar FPR to affect anything else. Jak is the king of ECU's so he can explain this better.
As far as running rich keeping things cool, that is not do to timing. Lean gasoline ratios burn hotter, so it is better to err slightly on the side of rich. Richness has nothing to do with how much mixture enters the cylinder, but everything to do with the ratio of air to gasoline that enters the cylinder. The 3 bar will help prevent leaning out at higher RPM by maintaining proper gasoline levels in the mixture during periods of high RPM that might overwhelm the stock FPR.
P.S. Tino, I am glad with the repair to the corroded plug fixed your car.
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