TypeTSX

Saw an advertisement for this "electric supercharger" on SCC magazine, so I investigated the website; it seems pretty interesting, possibly viable...relative to the gimmicks I've seen in the past.

"Our patent-pending ESC™-Series Electric Supercharger technology shocks the competition with up to 20 PSI of instant boost. Yes, we said 20 PSI. In 3/10 of a second. "

"The ESC-400™ features an Eaton twin-rotor core driven by three powerful electric motors on a CNC 60-16 T6 aluminum billet, so unlike conventional roots-type superchargers, it doesn't suffer the parasitic loss of a belt-driven system. And unlike the hundreds of failed Electric Supercharger designs before it, the ESC-400™ doesn't suck current straight from your alternator, the futile strategy of countless engineers unable to think outside the box."

Source: http://www.boosthead.com

TSX Hokie

Instead they use 50lbs of extra batteries? I couldn't tell from their website, but how are these batteries recharged? My guess is the alternator charges them. So you you take an engine that is roughly 25% efficient, convert some of its shaft power to electricity using an alternator that is 75% efficient, store it in batteries that are 90% efficient, then drive a compressor that is 70% efficient for an overall supercharger efficiency of 10-12%.

Compare that to a turbocharger, which is extracting energy from the 75% of the fuel energy that your engine didn't convert to power using a turbine that is 70% efficient, driving a compressor that is 70% efficient for an overall turbocharger efficiency of 30-40%.

I think I'll pass on the electric supercharger idea.

(Note, all these efficiencies are estimates, all on the low end)