gesTTalt

226.42 g/s @ 6160 RPM, manifold pressure 2250, temp reading 39*C (amibient temp of 84*F)

My setup is as folows:
Dahlback customed tuned
Forge FMIC
Airetek intake
Wilson Manifold
2.5" downpipe
3" hiflo cat
Milltek resonated

Could you calcuate the cfm from the info I provided?

john s

226.42 g/s @ 6160 RPM, manifold pressure 2250, temp reading 39*C (ambient temp of 84*F)

scfm = standard cubic feet per minute

There are as more "scfm" definitions than there are standardizing committees. I'm using the metric conversion of one commonly used in US (atmospheric pressure 1013 mbars, temperature 19°C, weight of cubic foot at this temperature and pressure 34 grams).

(226.42 g/s) / (34 g/cf) * (60 sec/min) = 400 scfm

So flow volume would be 400 cubic feet if air were open in the room. However air is being crushed into manifold by turbo, so we need to correct for temperature and pressure there.

Pressure correction:
(400 cfm) * (1013 mbar / 2250 mbar) = 180 cfm

Now we need to correct for temperature. At 0°C air will have considerable volume so you need to use the proper scale as was done for pressure (1013 mbars is 0 gage pressure), an absolute scale - Kelvin (273 K is 0°C)

(180 cfm) * (273 + 39)K/(273 + 19)K = 192 cfm

So air flow inside of manifold is 192 cubic feet per minute.

Do a block #120 log from idle speed to rev limiter in 4th gear to get torque & hp plot. A stock 225 will get a hp peak of about 197 hp on average at 5900 rpm. If you do this conversion (225/197) you'll probably be in the 280 hp range.

ZGTT

stuff "I" never did study in, graduate school ;-)
Thanks for the calculation support! I am glad for this forum and the synergy that it allows :-)

gesTTalt

as Bob stated, it's great to have your knowledge and I appreciate the way you share it.

john s

If you have VAG-COM logs of the various stages of tune, please send them my way; thanks.

gesTTalt

I do, I will put them together and send them to you.

john s

ok to just send raw files with descriptive names