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911st 911st is offline
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Join Date: Jan 2004
Location: Sacramento
Posts: 7,269
Originally Posted by beepbeep View Post

I wrote it in your other thread but I will cross-post it here:

3.3L engine turning @ 5500 RPM at 0.7 bar, producing 300 HP at AFR 13.0:1 (CIS goes lean on the top, remember?) at 92% VE, 50 deg. C intake temp and 29% efficiency will gulp 33,7 lb/sec of air and have per cylinder fuel flow of 262cm^3/min assuming 0.75 kg/L density and 43.8MJ/kg energy density of gasoline.

As stup did the measurements in "N/A" mode, there was no boost enrichment present, so control pressure would be still high.

In order to determine flow at boost, one must pressurize the WUR to 0.7 bar in order to dump control pressure to 2-3 bar, which will raise the injector flow over 240ml/sec.

That value is still not accurate as injectors fight against 0.7 bar of boost, which will lower injected value by couple of %.

But all in all, CIS is capable of spraying enough fuel to obtain support around 350is HP in its unmodified form. More than that and you would need to fiddle with control/system pressures (and airflow also gets impended by flapper, which is the main HP bottleneck).


Not correct, he did not do the measurement in n/a mode. He did it by pushing the metering plate to full travel so the head was flowing at it's max.

The WUR and CP only effects the rate the metering plate moves relitive to air flow.

All the WUR's boost enrichment dose it lower control pressure to the metering arm can advance further for more fuel.

Pushing it down by hand bypasses the WUR function totally.
Old 05-10-2009, 08:05 AM
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