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To cool or to squeeze-that is the question

On Tue, 17 Jun 1997, Robert Myers wrote:

> I'd wager that your turbo is able to provide about all the compressed air
> your car can use.  Better cooling might be the way to get more power more
> effectively.  

Hmmmm, Bob, I'd have to disagree slightly here, as I've been in a 5KCSTQ
with a high flow turbo that was very capable of using the increased 
airflow.   It was fast!

> You also need to be concerned about running excessively lean at max boost.

Very true.   The same car I was in was running dangerously (IMHO) lean.

> Really, Gross, the effects of pressure and temperature (absolute not F or
> C) are pretty much equal (but opposite directions, of course)  A 10%
> increase in absolute pressure will have about the same effect as a 10%
> decrease in absolute temperature.  The sticking point is that a 10%
> decrease in absolute temperature is a lot larger temperature change than
> most people commonly would think.  It must be the absolute temperature that
> is considered.  

Great - this was what we needed to know.   The point about temp having to 
be absolute is well taken here.   I'll keep that in mind from now on.

> As an example, a 10% decrease in temperature for air at 150 degrees
> Fahrenheit would be a 61 degree drop not a 15 degree drop.  You'd have to
> cool the air charge from 150F to 89F to get the same effect as increasing
> the boost from 8 pounds of boost to 10.3 pounds of boost.

Thanks, you're a good teacher, Bob!  :-)   (examples and everything!)

Graydon D. Stuckey 

"Cool name man!" - Jay Graydon   :-)