Thread: Engine Guru's, Help Me Understand Ignition Timing

Originally Posted by SyntheticShield

So we would want spark to occur say at 0* and maximum pressure build at 30* ATDC for example, correct?

in an ideal IC engine yes... but in almost every case, combustion chamber design, piston crown shape, fuels, detonation, rotating geometry all make for compromises for peak power

Originally Posted by archemedes

you also have to figure in the time it takes for the flame to ignite the mixture which I think (going back to my mechanics classes 15 years ago) is about 2*

by flame i assume your refering to the spark kernel (wheres that in cylinder vid of combustion at?)
that varies significantly with RPM/load

start reading this on your road to knowledge....rotating assembly geometry plays a huge part of spark timing and its effects...remember short rod engines are generally considered to be resistant to knock (however the 3800 has plenty of issues with Kr, but in my opinion that has alot to due with ring flutter and an oil scraper ring thats undersized...)

Connecting Rod vs. Stroke Analysis: panic Tech Paper No. 1