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      02-07-2009, 04:49 PM   #28
F104
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Belgium
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Drives: E92 320D M-sport
Join Date: Apr 2008
Location: belgium

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I'm struggling with this. Even though the air filters sits in an extreme corner away from the engine, where does it get its cold air from? At 6000 rpm and 0.5 bar boost a 3.0 ltr engine is sucking in about 13 m3 of air a minute. As a rough guess i assume that is 20 times the free space under the hood, eg every 3 seconds all that air is being sucked in. The far majority (if not only) of air coming into the engine bay is thru radiator and intercooler, unless one changes, and utilizes the airduct going to the brakes. But even then that flow would be minimal compared to what comes thru radiator and intercooler.

I can't do this in imperials, but if you had a proper 4" (that's 10cm to me) dia intake in the bumper directly going into the engine that 13 m3 would translate in 29 mtr/sec intake speed (or 104kph / 65mph)

Thus unless you have that 4" intake, and do 65mph before flooring the throttle (and some other physical losses aside), i kind of wonder where all that cold air comes.
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