SCratching my head on this. Spark blow out? Options

[wortdog]

IMO, The biggest reason Buschur runs lots of timing is the revs. On the Formula car, we saw about a 12hp difference between running 30 degrees of advance at 11,000 rpm and running 48 degrees of advance. This is on an engine with 12.1:1 compression that only makes 83hp total due to a restrictor, so I guess its not really a good example.

The way I think about it is that as the engine turns faster, you have less and less time to get the burn done in. There is also a constant factor of how long it takes from when the ecu tells the coil to fire to when there's an actual spark at the plug. The density of the mixture only comes in as a small factor compared to the size of the bore, as the biggest problem is getting the flame front to spread equally and quickly. This is one reason people have started running a second set of injectors in the intake runners close to the plenum, as the extra time before it gets to the cylinder helps promotes atomization at very high engine speeds/air flow rates.

If I had to guess, I'd say Buschur's timing table peaks out at around 38 degrees of advance at 9k rpm, assuming that's where his peak power is.

Those of you revving past 7k on the stock ECU would probably see gains if the advance map kept going up instead of peaking out.

Slightly off topic, but the interesting thing about dyno tuned fuel and ignition maps is that the torque peak is always right at the point in the fuel map with the largest injector pulsewidth, while the horsepower peak is generally right at the highest point in the timing curve.