electric superchargers

[Michael D. Porter]

Tom Cloud wrote:
> 

> 
> To digress slightly -- a 1000 cfm Rotron cooling fan,
> what benefits could one expect from putting something
> like that in the intake flow ???  It draws little juice
> and would insure a _slight_ positive pressure flow
> under all conditions -- and esp at low vehicle speeds.

I haven't seen a Rotron catalog in some time, so I've slept since then.
<g> But as I recall, a fan that size is fairly large. Might be a bit of
trouble getting it into the engine compartment. Also, most axial fans
are rated either in free air, or with a pressure drop across them of
perhaps 0.05-0.1 inches of water. As soon as you neck the output of a
fan down to that of the inlet manifold, you create a drop far in excess
of that and the fan output goes down dramatically, probably to the point
that the fan creates an inlet restriction for the engine. Turbos and
superchargers don't just move air, as an axial fan does, they compress
it--that's why it takes the crankshaft power it does to turn them. 

Rotron did make a centrifugal fan which could produce pressures of a few
inches of water loaded, but was quite large and ate lots of power. To
give an example, we use Rotron brushless motors in some vehicle a/c
units and the current draw is quite high for automotive circuits.
They're probably 1.2 hp motors, and at @ 24 volts, draw in the
neighborhood of about 35 amps (four are used in the application of which
I speak, and the four are fused at 150 amps). Your 12v car system would
have to be able to produce 125 amps, just to get 2 hp, and that assumes
no losses. 
 
Cheers.

-- 
My other Triumph doesn't run, either....