Re: Ram air?

[DeWitt Harrison <de@aztek.com>]

At 12:33 PM 6/17/97 -0400, you wrote:
>On Tue, 17 Jun 1997, DeWitt Harrison wrote:
>
>> absolute temperature are omitted. They do succeed in making a good
>> point, though. It is noted that any benefit from "ram air" intake
>> ducting comes from bringing cool air into the engine, not from
>> increased inlet pressure. They cite standard aftermarket air filters for
>
>The temperature thing is certainly important, but feeding the engine air 
>at 1psig is definitely better than at 0psig unless there are other 
>mitigating factors.   That would mean for example that my turbo only has 
>to pump the air 13psi delta instead of 14psi delta.   That menas the 
>turbo will spool up faster.  I think that might mean too, that the turbo 
>couild run at 15 psig, adn be at the smae efficiency as it was before at 
>14psi.
>
>> the VR6 which draw under hood air that is easily 100 deg.F hotter
>> than outside air. Not cool.
>
>Definitely not cool.
>
>Later,
>Graydon D. Stuckey 

Trouble is, Graydon, Bernoulli sez you'd have to be moving at about 250 mph
to make that 1 psi. The formula for velocity vs. Pitot (ram) pressure and air
density is available on a fluids class worksheet at http://www.coe.neu.edu/
fluids/pw3-26.htm. (Note: 1 psi = 6895 Pa.) Not much use for stop light
racin' anyway. I still think the intake air temperature issue dominates.

DeWitt