>.Now I know that leaf blowers are relatively high volume but what about
pressure? Of coures if this would work Paxton and what not would
long be out of business.
If only it were that easy! I am not an expert in Supercharging but I have
worked a little with blowers and compressors. Here is an explanation
from someone who knows just enough to be dangerous.
Most blowers (just like vacuum devices such as dust collecters) will go
to one extreme or the other. A leaf blower is a high volume but a very
low pressure. I guess that it probably 200CFM And it probably produces
about .1 PSI boost on a .25 HP motor.
An air compressor is the other extreme. A 5HP single stage
unit that is very efficient will get you about 11 CFM at 125 PSI. With
arelatively small amount of power you can get high volume with out a lot
of pressure (meaning under 1 PSI) or you can get a lot of pressure
without a lot of volume. Any time you want a lot of both you are going to
need a lot of power. A quick way to get a feel for the volume
requirement is with carberator sizing. A formula I got out of a book on
Holleys claims the correct formula to be:
CFM=Disp(CU inches)/2*Max RPM/1728*Head efficiency
Holley claims that most unmodified production heads are about 75-85 %
efficient, a well designed haed ported and polished will exceed 95%.
For a 2.5 liter motor with 85% efficient heads and a max RPM of 5500
RPM you require about 200 CFM. If you want a benfit from the blower
you are going to need to provide 200 CFM with a minimum 7CFM increase
in pressure. This will require a fairly large amount of power like maybe
20-30 HP ( this would theoretically give you a 50 percent boost in power,
say from 150 to 225 HP) . One of the best clues to that fact that
Superchargers require a lot of power is the size and shape of the belts
they use, they dont use very wide notched belts for looks it is to handle
all the power required to run the motor.
Sorry to blow so much hot air.
Tom Leake
Opinions expressed do not reflect those of my employer!
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