Mercedes-AMG is putting some Formula One technology under the hood of its new SL 43, and while it’s still not certain we’ll be getting this version of the SL in Canada, it’s worth a peek for its electrically-assisted turbocharger.
This version, with a turbocharged 2.0L four-cylinder, will be the entry-level model in the SL lineup, alongside the V8-powered SL 55 and SL 63 models. The technology was used by the Mercedes-AMG Petronas F1 team, and the automaker says it’s a world-first for it to appear in a production vehicle.
The system uses a very thin electric motor, only about four centimetres wide, that’s placed on the turbocharger shaft, between the exhaust turbine and the compressor wheel. When activated, it directly drives the shaft to accelerate the compressor wheel, spinning it before the stream of exhaust gas starts to drive it — which means turbo lag is now basically just a memory.
Mercedes said it improves both the response from idle speed, and also across the engine’s entire range, enabling higher torque at lower engine rpm. The electric motor is also able to maintain boost pressure at all times, even if the driver takes a foot off the throttle or applies the brakes.
The SL 43 includes a 48-volt mild-hybrid system with a belt-driven starter-generator. The electric turbo assist runs off the 48-volt system, and the turbocharger can spin at speeds up to 170,000 rpm. The engine’s output is 381 horsepower, while its 354 lb-ft of torque is available from 3,250 to 5,000 rpm. The starter-generator can also pump in an extra boost of 14 horsepower for short periods, depending on driving conditions. The mild-hybrid system is also used to smooth the transition when the start-stop system starts the engine, and provides a fuel-saving “gliding mode.”
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Mercedes-AMG said the electrically-driven turbocharger “solves the trade-off” between a small, fast-responding turbo that only achieves comparative low peak power; and a larger one with higher peak power but with a delayed response.
The automaker has used the four-cylinder engine transversely in its compact models, but mounts it longitudinally in the rear-wheel-drive SL 43 and adds the electric turbo assist. The SL 43 can accelerate from zero to 100 km/h in 4.9 seconds, with a top speed of 275 km/h, while in European testing it rates as low as 8.9 L/100 km.
Keyword: Mercedes-AMG adds F1 electric turbo tech to its SL 43