Mitch---At the risk of boring the socks off those who have little
interest in the working of forced induction units, I will offer the
following, more or less taken from a book chapter for "Computing
intake-charge temperatures".
First, a yes to your question. Ambient air temps figure into the
calculation of final air temps produced by compressors. To a large
extent, so does the design efficiency of the compressor. Most fall into
the area of between 50 to 70%. This percent is called the Adiabatic
Efficiency.
Ideal Temp. Rise/Adiabatic Eff. = Actual Temp. Rise.
There are many pages dedicated to what all goes into the formula for the
charts showing the various percentges. Too many to list here, and
scanning isn't permitted. But for sure, the temp of the air that goes
into the compressor influences the air temp of what comes out.
To give just one of the examples, if you start with air at 80 deg.F.,
compress it to a pressure ratio of 1.9 (13 lb. of boost at the gauge)
and have a 65% effciency, you end up with air at 245 deg.F. This
temperature is cooled off to a large extent when it picks up the fuel,
before entering the engine. More so, if this air sees intercooling and
or water injection.
Anyone still awake?
Dick
From:
ms6453@optonline.net(Mitchel Seff)
Cc: kmcnelis@nmsu.edu (Dr L. Kevin McNelis),
Hi all,
I absolutely do not claim to be an expert ( I'm always amazed things
work after I finish :-) )on the theories of supercharger design &
application but wouldn't there be other factors affecting adiabatic
efficiency of individual units, such as present air temperature, fuel
temperature & actual design. I would imagine some units may be more
efficient than others. This was one of Eatons claims when I was hooked
on this in the beginning . I have never dyno'd the car but I am curious
and would like to know the numbers. If I get the opportunity to do it
I'll share the stats with the list.
Unfortunately the design for this car with the SC mounted on the intake
side does not allow for an intercooler. I have seen some mount the
blower on the other side of the motor and route the intake through an
intercooler to the intake.
All of this in an exercise in fun , learning & discussing new
technologies with friends. I learn something new every day, sometimes I
even understand & remember it !
--
Mitch Seff
Oceanside N.Y.
75 TR6SC
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