Air Flow Measurement

[RABBITT_Andrew at mv8.orbeng.com.au]

> What is the best way to quantify the error on an actual engine?

The absolute best way is on an engine dynamometer, with a large volume 
(1000+ litres) hanging off the end of the inlet system and a reference 
meter upstream of that.  Other than that, you could use your 
closed-loop A/F controller to give you an idea of how far out you are. 
This is assuming that the fuel injectors are flowing accurately.

>Most cars with MAF have some complex air chamber configuration 
>between the MAF and the throttle body.  I always thought this was for 
>minimizing the induction noise at WOT.  Are the chambers there to 
>minimize flow reversion through the MAF?

I wondered that too, so we tested an inlet system that had a couple of 
helmholz resonators fitted as standard (same engine, different 
vehicle) and came to the conclusion that it wasn't going to help me 
very much.  It changes the amplitude slightly and adds a phase shift 
to the signal, but I think they're almost entirely NVH mods.

Andrew Rabbitt