Electrical Supercharger

[Steve Meade]

	I noticed a while back (over a year ago) there was a discussion about
electrically powered superchargers. I was wondering if anyone actually
followed through on plans and tried it. To me, there are several advantages
to electrical power over the traditional crankshaft power:

	1. Cost (electric motors are less than blowers and don't strain engine as
much)
	2. Placement -- the placement isn't dictated by crank positioning.
	3. Ease of installation -- no need to completely tear apart front of
engine
	4. Adjustability of boost -- a simple 2-d rpm and boost mapping system can
be made

	However, I was thinking of the extra energy losses by using an electrical
blower. In a regular system there are only two possibilities for energy
loss:

	1. Crankshaft attachment scheme / gearing (if any)
	2. Impeller / screw losses

	An electrical system incurs three energy losses though:

	1. Alternator inefficiency
	2. Electric motor inefficiency
	3. impeller / screw losses

	I was wondering whether or not a system could be developed to produce 3psi
or so. That would be enough to satisfy my performance cravings for now.
About how much power could one expect from just a couple of pounds of
boost? Remember, the blower wouldn't consume any extra power off the engine
if using the stock alternator. On my car, a BMW 325is (relatively little
displacement of 2.5liters) a regular supercharger kit costs around $6K! As
you can imagine, I would be very willing to accept a fraction of the power
boost for a small fraction of that cost. Also, designing the system myself
would be fun. 

=-=-=-=-=-=-=-=-=-=-=
Steve Meade
smeade at deltanet.com