Megasquirt Advice and discussion.

[RETed]

Originally Posted by RotaryProphet

15psi is always 15psi, but 15psi at 80 degrees is not the same as 15psi at 160 degrees; this being what compressor efficiency is measuring (heat added to the intake charge). A larger compressor will generally have better efficiency numbers higher up in the airflow range, and a wider efficiency island.

You aren't changing the "flow", persay. Given a certain engine condition with a better compressor, you're flowing the exact same volume of air (assuming you have the exact same pressure), but the better compressor will be pushing a cooler, and thus denser air charge. (Which would be mass, as opposed to volume).

This is why a MAP based system also requires an intake air temp sensor to correctly calculate the air density. A MAF system measures mass directly, and is probably more accurate under a wider range fo circumstances, but the restriction to inlet flow leads me to use a MAP/IAT system 90% of the time. I would choose a MAF for things like hill-climb motors where rapid changes in altitude would necessitate the wider operating range, and self barometric correction would be more desirable.

Sorry, but you are dead wrong.

TTT is right.
Pressure (i.e. "psi") is only one variable when talking about turbo potential.
AIR FLOW the other big variable.
To ignore air flow is downright stupid.
15psi with a T3 is not the same as 15psi with an HKS T51R SPL...

Air temperature is tied into the whole thing (see PV=nRT), but it's a relatively minor variable.
To emphasize air temps over air flow is downright...ignorant.


-Ted