Lower Emissions and More Power From An Electric Supercharger That Really Works
I’ve spent a lot of time around the car hobby, and I’ve seen some pretty stupid people do some pretty stupid things. My favorite story involves a V6 Mustang and a leafblower strapped to the air intake, approximating a cobbled together stand-alone supercharger of sorts. Alas, no one ever explained to this man-child that if you add more air, you also need to add more fuel. His engine did not last too long.
But a UK company may be on the right track with an electric supercharger that actually works. Not only does it provide a 40-50% bump in power and torque, but also a 20% decrease in CO2 emissions.
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A quick primer on superchargers. The typical supercharger uses a belt, wrapped around the front of the crankshaft, to turn a turbine mounted in front of or on top of the engine. This pushes more air in, allowing more fuel to be burnt, and more power to be made. Superchargers are often used in performance applications like the Shelby GT500.
The electric supercharger by Controlled Power Technologies (CPT) uses electricity, rather than the host engine, to turn the turbine. This eliminates parasitic horsepower loss cause by the belt required to turn the turbine (every belt-driven system on your car drains horsepower, the more belts you have the more horsepower you lose). When tested on a 1.2 liter turbocharged engine, the results were 59% more torque at low RPM without any additional CO2 emissions. Electric superchargers could offer a promising alternative to more costly ways of improving power and fuel efficiency, though it is hardly a solution to all our problems.
Still, I want one for my Jeep…
Source: Inhabitat | Pictures: CPT
Technically, the electric supercharger will still involve parasitic loss as it will require power from the belt-driven alternator which will be significantly harder to turn when powering a supercharger than when not.
(If you’ve ever been sitting in traffic and heard your engine bog down when your electric cooling fans came on, it’s the alternator that’s bogging it down.)
Nevertheless, it’s still a viable alternative to belt-driven superchargers and gives a lot more freedom for where the supercharger can go in the engine bay.
One more thing I like about electric SCs is that they can be controlled with a switch. E.g. if you’re coasting down Pike’s Peak, there’s no reason to have your supercharger running, so you can just switch it off. Not possible with a belt-driven SC.
Almost always that “bog down” sound is caused by the A/C compressor kicking in. I have never heard my car “bog down” when I am not running the A/C, even when I hear the fans kick in. Almost always the fans automatically come on when the A/C turns on too.
Also, an electric supercharger used at low end speeds drastically helps the acceleration and drive-ability of the car in small bursts, instead of always being attached to the engine. The SC can run off an aux battery when needed for short bursts w/o affecting engine performance, e.g. loading the alternator. And the aux battery can be recharged at a much slower rate when cruising taking advantage of the turbo chargers higher end performance gains.
This creates a sequential two charger system, electric SC is active way before turbo assist comes in, and turbo takes over when its benefits come in.
“Almost always that “bog down” sound is caused by the A/C compressor kicking in. I have never heard my car “bog down” when I am not running the A/C, even when I hear the fans kick in. Almost always the fans automatically come on when the A/C turns on too.”
Just to clarify, I’m talking about when you’re sitting idling in traffic on a hot day.
That’s also true about the A/C, but I’ve definitely noticed it with just the fans, because I rarely use my A/C. I’ve also noticed it when I turn on my headlights. The engine has more of a load on it and often the computer may compensate by slightly increasing the rpm…so rather than a bog, you might get a slight rpm surge.
The fact that this is electric means they can take advantage of selectively turning on and off when needed. I doubt it will turn on when you’re sitting at idle speed so don’t worry about that bogged down feelin’.
I agree that if they use a separate battery that can be charged at cruise speeds, that would give the most bang for the buck.
If the price isn’t too steep, this could add some life to reasonable cars and keep them on the road a bit longer.
Why not build an electric clutch into a standard supercharger pulley, similar to the A/C clutch.
An auxiliary battery and the motor that powers the supercharger is extra weight to carry around when you don’t need it.
@colin-
I believe the older supercharged Toyota MR2’s had a setup like that.