Quote Originally Posted by anjin View Post
I did an exercise on engine cycles a while ago, and one of the things that really made sense was the interelationship between compression ratio (however achieved) and timing. The maximum pressure developed in the cylinder should occur about 14/15 degrees after tdc - at that point the force developed will force the piston and rod around the crankshaft. Any earlier and you are trying to force the rod through the crankshaft. Any later and you are past the optimum leverage point as the mixture expands and the piston accelerates away down the bore.
Now in order to get maximum pressure at that point you have to start the fuel air mixture burning much earlier -before tdc. That is why you have a static ignition point at say 16 degrees BTDC and it advances to even earlier at higher revolutions - the fuel-air mixture burns at the same pace at 1000 prm as 8000 prm.
But it burns faster at higher compression ratios. So to get maximum cylinder pressure at 14 degrees atdc with high compression ratios than stock you actually have to retard the timing.
That is where a lot of the tuning skill for engine longevity comes in when you boost engines.
NS dude?

where u learn that man u sound fairly knowledgeable.