381 hp from 2.0L eTurbo-four
Electric turbo borrows tech from Mercedes F1 racer
Mercedes-AMG doesn’t want buyers of the new four-cylinder SL model to feel left out. So the automaker has given the 2.0L engine a 48V electric booster as well as a fancy new turbo it says is a direct derivative of the one that the Mercedes-AMG Petronas F1 team used to win multiple F1 championships.
The Mercedes-AMG SL 43 won’t grab headlines like its V8 siblings, and it might not make the same level of fancy engine noises that those cars do, but it makes up for it in technology.
Merc calls it an electric exhaust gas turbocharger, and it attaches an electric motor directly to the shaft in the turbo that runs between the exhaust turbine and intake compressor wheel. The small motor, just 4 cm thick, lets the turbo spool up long before the flow of exhaust would spin it quickly enough to make boost naturally.
The result is near-instant response since there’s no waiting for exhaust flow to increase to build pressure. The electric turbo also lets Mercedes offer more torque at low RPM while still having enough flow for big power at the top of the rev range. Even better, it allows for the turbo to keep spinning when the driver has their foot off of the accelerator, giving the SL 43 race-car-like anti-lag without the noise, emissions, and possible mechanical damage of those systems.
Peak power is 381 hp at 6750 rpm, nearly 200 hp per litre. Peak torque of 354 lb-ft arrives from 3250 rpm and continues all the way to 5000. The 48v mild hybrid electric motor-generator that works as the starter can add 14 hp in short bursts in certain situations.
Backing the four-pot will be a Mercedes-AMG 9g Speedshift transmission. While a variant of this 2.0L engine has been used in front-drive Mercedes-AMG models for a few years, this is the first time it will be mounted north-south, and that has allowed Mercedes to use a dual-clutch transmission with it for the first time. The new Mercedes-AMG SL 43 is expected to go on sale later this year.