DETROIT -- Valeo has developed an electric turbocharger that it says eliminates turbo lag.
The new turbocharger is powered by an electric motor instead of exhaust gases.
When not needed, the turbo's impeller, which pumps air and fuel into the cylinders, still spins at 10,000 rpm, so there is minimal hesitation or lag in engine response when the driver presses the accelerator pedal.
But there are downsides: cost and power consumption. The unit requires 48-volt power, which means additional electronics under the hood. It also is a heavy user of electricity.
Still, automakers are intrigued.
Audi has been testing the electric turbocharger and is expected to be first to market the device. Audi will apply an e-booster electric turbocharger to its 3.0-liter V-6 diesel engine in the Q7. This uses an electric compressor to spin up the turbocharger from very low revs to cancel out turbo lag.
"The new Q7 will be in the market next year and the electric turbo will come a little later in a sporty version called SQ7," r&d chief Ulrich Hackenberg said at press event last month in Denmark. He did not say which supplier would provide the e-turbocharger.
Mercedes-Benz r&d chief Thomas Weber says the technology is relevant and a valid option when mated to 48-volt or higher voltage systems. "It is a real alternative to two-stage turbocharging," he said.
Two-stage turbos use two fans -- one for low speeds, another for high speeds.
BMW engine development manager Nikolai Ardey says the company is studying the technology but is looking at alternatives as well.
A powertrain expert at General Motors described the technology as "very interesting" and "under study."
Valeo says the electric turbocharger can reduce fuel consumption by between 7 and 20 percent.
Curt Estes, Valeo's regional operations director of powertrain systems, said 20 percent reduction is possible when the device is used on a vehicle equipped with regenerative braking, which captures the car's kinetic energy and turns it into electricity