Sorry Phil!

Had to play with you just a bit... the fuel map was an aside referrring to Megasquirt's fuel map (VE table) which we were talking about just a while back. Necessarily, with the DCOs you set a configuration and there is a limited ability to respond to outside influences.

From your charts I see what you mean, starting at about 3000 rpm things get wonky and the mixture gets way fat. I assume you suspect some sort of bad scavenging by the exhaust. Boy that's some tricky stuff in there, pulses, reversions, standing waves. Maybe sort of flow disonance or standing wave then recedes by the time you hit 4000 rpm. Every little bend and nuance affects the output across the operating range. Nip a little here, tuck a little there until it is just right!!! Problem is, which is the right nip or tuck. So many to choose from eh. Yes "They be dragons in here"!

If you were in a closed loop mode using EFI, I assume the CPU would then just respond to the sensed condition and roll back the fuel and power on through, or is it possible the dynamics of the exhaust flow can be so dominant as to radically alter gas flow thoughout the system regardless of fuel system response? At some point, one cannot draw a walrus through a soda straw, I suppose!

Another unique glimpse of what it takes to make that kind of power with a 40-plus year old power plant design, (or any motor for that matter).

Interesting stuff... that I am sure gives you fits!

Thanks Phil

Mmike