Megasquirt Advice and discussion.

RotaryProphet · 12-13-2009, 11:14 AM

Also, in a properly setup and tuned speed-density system using a MAP and IAT to calculate air density, and a VE table to calculate cylinder filling, swapping turbos, even with very large efficiency differences, results in very small tuning changes, and most of that is from hitting areas of the map that the old turbo wasn't capable of hitting.

NoDOHC is dead on about tuning spark advance with a MAF, too. If you're flowing a moderate amount on a turbo engine, you wouldn't be sure if you were near your redline and just about to start making boost (relatively high spark advance) or if you were at 3500 and already at max boost (very low spark advance); but it knows how much air is there, and adding the appropriate amount of fuel to it is semi-trivial. It is possible (and this is how the MS works if you use a MAF sensor) to map MAF vs RPM for ignition timing, which is almost as good as a MAP. Although, the MS has a MAP on board, so, it's all hypothetical.

12-13-2009, 11:14 AM	#1
RotaryProphet Rotary Fanatic Join Date: Sep 2008 Posts: 147 Rep Power: 18	Also, in a properly setup and tuned speed-density system using a MAP and IAT to calculate air density, and a VE table to calculate cylinder filling, swapping turbos, even with very large efficiency differences, results in very small tuning changes, and most of that is from hitting areas of the map that the old turbo wasn't capable of hitting. NoDOHC is dead on about tuning spark advance with a MAF, too. If you're flowing a moderate amount on a turbo engine, you wouldn't be sure if you were near your redline and just about to start making boost (relatively high spark advance) or if you were at 3500 and already at max boost (very low spark advance); but it knows how much air is there, and adding the appropriate amount of fuel to it is semi-trivial. It is possible (and this is how the MS works if you use a MAF sensor) to map MAF vs RPM for ignition timing, which is almost as good as a MAP. Although, the MS has a MAP on board, so, it's all hypothetical.