On K&N’s dyno, the new M3 put down 379 horsepower at 6600 rpm and 378 lb.-ft. of torque at 4300 rpm. Official figures show the engine being rated at 425 hp at 5500 rpm and 406 lb.-ft. of torque at 1850 rpm.
Using 13 percent as a rough estimate for drivetrain loss, the two figures are matching but the peaks are different.
As explained by Albert Biermann in a recent chat, the curve of the S55 engine is where we should be paying attention. Basically the power delivery is consistent and available across the entire RPM range.
The torque build-up starts way low compared to the previous 4.0 liter V8.
The chars also show that horsepower doesn’t begin to fall off until before 7000 rpm, and not by much.
The S65 4.0-liter V-8 was also dynoed. The charts showed it produced 306 horsepower at 7600 rpm and 238 lb.-ft. of torque at 3850 rpm.In isolation, it’s a beautifully shaped power band, delivering flat, consistent torque and a linear build in power throughout the rev range.