Max Timing vs compression stroke???

[Ben Charles]

Been doing some reading on greg banish's books and another one called "performance fuel injected systems" and after reading up on ignition timing I have a question.

Many people seem to find the max timing values by adding timing till knock (detonation then backing off a couple of degrees). However, making the cylinder pressure rise too fast can hurt power even if it doesn't lead to detonation. So values much before detonation occurs would make the most power??

Here is an example (made up numbers). Say at WOT 27 degrees shows some slight knock most people would just back it off to 25 degrees and call it good. But from my reading, max power might be possible further away from that at say 22 degrees.

Much of this could be identified on the dyno, but for those of us without this tool, anyone have any experience with this or rule of thumb??

[Wnts2Go10O]

i think the idea is to have the mixture burn/explode to provide the most force on the piston that it can. i think another factor is a bit more complicated.. has to do with the rotating assembly and the inertia it can develop. if youre pedaling a bike, there are certain parts of the rotation that provide more force that others and you can build up "power" as you go faster and faster. same thing with engines... there are simply parts in the 360* circle that will provide the most push.

if someone else can explain it better... please do..lol

[KFZ)^]

Yeah Ben, it is amazing what can be learned when you take the time to research a subject Beyond The Internet Consensus. You are exactly correct that the method of "tuning" that involves increasing the spark advance until knock is encountered, then decreasing the advance until the knock subsides is not always the best method. It is however, a Close Enough For The Average Guy Method, hence it's popularity.
However, We the Enlightened are aware that the spark advance required to produce Maximum Brake Torque is a moving target and that's why people like Greg get paid the big bucks.