[lust4speed]

Originally Posted by steve25

...The post last week of the W72 400 motor build and the 42 degrees of timing that was employed is a clear cut example of this!

Agree with almost all of your analysis. The slower burn is why we start the combustion process earlier so it will be done by the time piston reaches BDC. If we didn't bump timing then the combustion process would still be going on at the bottom of the stroke. With proper timing both high and lower compression should have the optimum burn ratios and be done at the same position of the crank.

Most "hot" engines are those where the compression ratio is too high and timing is retarded in a band-aid approach to subdue detonation, and this process does have the process starting late and finishing late with a lot of heat still being released at BDC.

RAMAIRNACHO, our builds are always compromises. 2.41 gears are excellent on the highway, but starting off is like taking off in 2nd gear compared to a 3.31. With a 1:1 final drive ratio decisions have to be made, and why many of us end up with an overdrive trans.