At 08:21 PM 7/17/2001 -0400, Kai M. Radicke wrote:
>> .... Basically find an air pump from a large american V8 and use it to
supercharge a small 4-cyl via a preassurized airbox. ....
>> --
>> James Nazarian Jr
>
>That's a bloody stupid thing to do. An airpump is much like a centrifugal
supercharger, it has an impellor and is driven by the motor via a belt.
Now the main thing with centrifugal superchargers and turbochargers is that
the tip velocity of the impellor needs to reach speeds near the speed of
sound for them to be efficient (or rather the efficiency increases the
closer they near that figure). This means that the centrifugal
supercharger and turbocharger's impellor tip velocity routinely reaches
120,000RPM+. Will that airpump be capable of that?
>....
I suppose I could wait for someone else to do some flaming or arguing here,
but I would just like to remind Kai that most "air pump from large American
V8" are not fan type blowers but are vane pumps with positive displacement
and will output a moderate pressure at a fairly slow speed. Maybe he has
never looked inside of an air injection pump stripped off of a late model
LBC in the process of desmogging.
While I have seen these used quite successfully for supercharging a shop
air compressor, I don't suppose the boost pressure would be quite enough to
justify messing with it on a car engine, although Judson seems to have made
quite a bang out this with their vane pump superchargers in the 50's,
claiming up to 50% increase in torque. One (not so great) example here:
http://www.infostuff.com/carstuff/mgacbc/mgajudson.htm
The main problem(s) with a vane type compressor is heat and noise, both of
which lead to compressor inefficiencies.
Barney Gaylord
1958 MGA with an attitude
http://www.ntsource.com/~barneymg
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