I think this will be a simple question but I'd like the people here with a sharp understanding for these things to chime in.

How dramatically does timing affect HP. I realize it's not going to be linear but I'm not looking for exact figures. Here's the application: 383 a little over 11:1 compression. Current spark advance is at 29 degrees at WOT in the higher RPM range say above 4000 rpm. Output with these numbers was 350 RWHP and 371 RWTQ. Spark was dialed down to avoid detonation and had previously been around 34-36 degrees although I never did a pull with the spark set here. Anyone have any idea as to what kind of increase in power can be expected with the timing bumped back up 4-5 degrees?

 

It not a case of "more is better". Every combo will have an optimal advance. Exceed it and power drops and you risk detonation. Lower than the optimum you lose power. There are many variables that determine optimum advance. These include head material and design, CR, rpm, operating temps, fuel octane, etc. It's difficult to predict optimal timing unless you have worked on a near identical combo. The way it's done on a dyno is to sneak up on it. Start low and increase in small increments until power levels off and/or detonation occurs.

I'd hazard a guess that the OEM's do it empirically. It would be very hard to predict optimum timing, though I'd guess with sufficiently sophisticated simulation software and extensive knowledge of a given engines operating characteristics you could come pretty close.

Rich Krause

 

Tune it at the track. That's the only way to do it right.

You're looking for best mph, not ET. And keep things as identical as possible run to run.

-Mindgame