Electric Superchargers...

[David Cooley]

At 05:00 AM 9/16/1999 -0400, you wrote:
>We've all (or many of us) heard/read about the "electric superchargers"
>that have been marketed recently, these are devices which connect to the
>intake and blow in air - but they are electric powered.  They typically
>run for short bursts of time to provide just a little extra grunt when
>needed, and usually on naturally aspirated engines, especially diesels.


The only electric unit I had heard of was from a company called Powerdyne.
It isn't a supercharger, it's a motor that spins your turbo up a bit (not 
enough to make any measureable boost) to eliminate lag.


>Well, has anyone thought of doing this *right*?  Install additional
>alternator capacity to support running the unit consistently.  Put in an
>intercooler, etc. to support higher boost levels, like a real turbo.
>
>Such a system has the following advantages:
>
>1) More fuel efficient than a supercharger
>
>2) Very little turbo lag
>
>3) Very precise and simple control of boost (electronic control system can
>directly vary impeller speed to control boost)
>3.5) Knock sensor system can now reduce boost as a way of preventing
>detonation!  Oh happy day.
>
>4) No parasitic drag when not in operation; relatively little even under
>boost
>
>5) Can build boost on the line even with manual transmission, for drag
>racing, or at low RPM, for road courses/autocross
>
>6) Easy to install.  No need to fuss with the exhaust.

You don't get something for nothing, and nothing is 100% efficient or 
greater...
A typical automotive alternator is about 80% efficient at converting HP to 
electric power...
A typical electric motor is about 80-85% efficient at converting electric 
power to HP.
A typical blower takes 30-40 HP to make enough boost to be worthwhile... A 
turbo, while not as easily measured for HP drop (caused by exhaust 
restriction) is a bit more efficient.
For an electric motor to make 30-40 HP, it would take 37,300 watts of 
electrical energy (at 80% efficiency) which is 2825 Amps at 13.2 
volts...  For an alternator to replace this, if it had the capacity, it 
would take 62.5 HP...  The boost you make would probably give you a 30% 
increase in HP, so if you were 200 HP stock, your now at 260, but you're 
dumping 62.5 into running the boost...  You've actually dropped from 200 
available HP to 197.5 HP, plus the added penalty of 300-400 pounds in 
weight for the huge battery/alternator/motor combo.
If you want efficient, economical boost, Open the exhaust and insert a 
turbo... It operates on demand, cruising down the highway it has no effect 
on mileage and it's always there when you need it.
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David Cooley N5XMT Internet: N5XMT at bellsouth.net
Packet: N5XMT at KQ4LO.#INT.NC.USA.NA T.A.P.R. Member #7068
We are Borg... Prepare to be assimilated!
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