Electric Superchargers - the Next Big Thing for the Automotive Industry

It's a well-known fact that through downsizing, the act of turbocharging is gradually phasing out the good old naturally aspirated linearity due to obvious reasons. More ponies, more torque, lower CO2 emissions and better fuel efficiency are the most important benefits of forced induction. Still, turbocharging can go only that far, which is the reason why new tech is in development nowadays.
Valeo Electric Supercharger 1 photo
Photo: Valeo
The electric supercharger then. Don't be fooled by the supercharger bit because it has nothing to do with the mechanical air compressor that gives you more horsepower and twist by forcing more air and gasoline to the engine's combustion chambers. In plain English, the electric supercharger is basically a fan that pressurizes the air available to the engine's intake system.

Current Formula 1 single seaters and the Audi R18 Le Mans racing car use a sort of mashup between a turbocharger and an electric supercharger to get those ponies and virtually instant throttle response. With the technology still in its infancy, not even the motorsport-spec e-superchargers aren't 100 percent lag-proof, but still, forced induction of the near future will employ this high-tech contraption.

The new kid on the block also appeared right on time to fully mature by 2025, when the 54.5 mpg CAFE requirement will be mandatory for the US automotive industry. In terms of main components, the e-supercharger is essentially a turbocharger at one end and a DC electric motor at the other. These two are mated through a metal rod and between them there's a low-friction center support bearing.

Curious about how the electric supercharger works?

Simply put, this engineering marvel is employing a switched reluctance motor that can spin up to tens of thousands of revolutions per minute in less time than it takes to blink. Naturally, the DC motor uses electricity to do its job, electricity sourced from a battery pack that's recharged through regenerative braking or some other mean. Thanks to the DC electric motor, the turbocharger from the opposite end of the e-supercharger is put in motion much faster than an exhaust-driven turbocharger does on its own.

In the same manner a normal turbocharger or a belt-driven centrifugal supercharger work, the electric supercharger compresses air that'll eventually be sent to the cylinders for bigger bangs. The biggest difference between it and normal forced induction is that in this instance, an electric motor spins the compressor, not the exhaust gas as on the turbo you get on everything from a TDI-powered VW all the way to the track-focused Nissan GT-R Nismo.

The bottom line is that the turbocharger is supplied very rapidly with more psi of boost pressure thanks to the electric motor's help, enhancing a vehicle's go-faster capabilities all while using less fuel and emitting less carbon monoxide. But there's a small limitation to the e-supercharger - while the electric motor takes care of low speed boost pressure and transitions, the electric motor doesn't help high in the engine's rev band. At higher rpm, the normal, exhaust-driven turbocharger handles stuff alone.

Can I buy a car with an e-supercharger now?

Only if you have enough money to buy a Formula 1 racer, unfortunately. The only way to go is to get an aftermarket electric supercharger off eBay, but we'd rather not recommend enhancing your car this way. Why? Because most e-superchargers kits are just glorified fans that don't offer any extra oomph.

Wait a couple or years or so because only then we will get an adequate electric supercharger for road-going vehicles. Certain mainstream carmakers are working on it, most notably Kia with their Optima T-Hybrid Concept electric supercharged turbo diesel sedan, as well as the cool Audi RS5 TDI Concept.

Earlier this year when Audi revealed the RS5 TDI Concept, the German premium automaker also brought an A6 TDI Concept thingy. Want to know what's the difference between a normal 3.0 BiTDI Audi A6 and the A6 TDI Concept? Well, one of the two exhaust-driven turbochargers was replaced by an electric supercharger. That's all. With this setup, the A6 TDI Concept cuts the normal A6 3.0 BiTDI's sixth-gear acceleration from 60 to 120 km/h (37 - 74 mph) from 13.7 second to a mere 8.3 seconds.

And it does that by taking care of the sub-1500 rpm range, the one that isn't turbo-enhanced by the normal 3.0 BiTDI. It's a doable concept this and we have a sneaking suspicion the next-generation Audi A8 and Q7 are going to adopt this exhaust-driven turbocharger + electric supercharger setup.

Until the electric supercharger gets to be mass produced only time will tell, but its as clear as day this is what the future of motoring is going to look like. Don't forget that Audi research & development chief Ulrich Hackenberg told the A6 TDI Concept's tech could come to market by 2016.

Furthermore, Mercedes-Benz R&D chief Thomas Weber declared that the e-supercharger could become "a real alternative to two-stage turbocharging", both "relevant" and a "valid option" if Mercedes engineers develop a good enough 48-volt voltage system to provide sufficent zap for the electric supercharger.
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About the author: Mircea Panait
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After a 1:43 scale model of a Ferrari 250 GTO sparked Mircea's interest for cars when he was a kid, an early internship at Top Gear sealed his career path. He's most interested in muscle cars and American trucks, but he takes a passing interest in quirky kei cars as well.
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