[s-cars] RE: [200q20v] intercooler

mlp mlped at qwest.net
Mon Dec 3 17:14:19 EST 2001

Sorry Brian, I think our response may have "crossed" in the mail.

Actually after looking back over some old notes, 1.67 cfm per bhp
would have been a closer ROT (Rule of Thumb") guestimate figure.  So,
yeah, what you now say is in the ball park as far as I can tell.  This
also checks, I think with the "....by 360 cfm, your K24 is pretty much
maxed out...." comments I hear from various "turbo" people.

Now, I think one of the next little bits of information one might want
is "How fast is/does 328 cfm (or 360 or whatever you are looking to
push) have to be moving to make its way through a say 2" diameter
orifice?  How about a 1.75" orifice/  What the guess as to the
"effective" diameter for the UrS4/6 throttle body?  I can tell you the
TB is 2.6" in diameter on its "exit" side (i.e. the face that's bolted
to the intake manifold), less whatever allowances one makes for the
throttle plate shaft and butterfly valve mit "aero wedgie control

Anybody got a formula for that, air speeds?  I gather the critical
speed threshold for moving a lot of air for motor purposes (i.e. aka
"The Wall") is something right around 1/4tr the going speed of sound?


> -----Original Message-----
> From: Brian Link [mailto:brianl at starsys.com]
> Sent: Monday, December 03, 2001 2:21 PM
> To: 'mlp'; 'b.m.benz at prodigy.net'; 'brett at cloud9.net'
> Cc: 'Scott Justusson'; '200q20v at audifans.com';
> 's-car-list at yahoogroups.com'
> Subject: [s-cars] RE: [200q20v] intercooler
> Let me finish...
> 208 cfm is NA at 20psi and 5300 ft elevation I get 328
> cfm...Suppose that I
> get around  260bhp at 5300 rpm then I get 1.2 - 1.3 cfm /
> bhp.  I could see
> 1.6 being close at sea level.  Thats just about a 20% loss for our
> altitude.
> Brian

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