Add 2020 Porsche 911 to list of engines with underrated output

Motor Trend took a 2020 Porsche 911 Carrera S to a local dyno, and made what is becoming a not-so-unusual discovery: Porsche’s mid-tier sports car hides behind underrated output figures. The manufacturer specs for the 3.0-liter twin-turbo flat-six hanging in the 911’s rump are 443 horsepower and 390 pound-feet of torque at the crank. If one estimates 10 percent of that power drained through parasitic losses in the drivetrain, that would mean 399 hp and 351 lb-ft at the wheels on the dyno. At losses of 15 percent, the tally would be 377 hp and 331 lb-ft. Instead, the Racing Yellow coupe lived up to its color, turning in an average output of 414 hp and 406 lb-ft of torque over three runs in fourth gear. Those numbers equate to a horsepower loss of just 6.5 percent and torque that’s 104 percent of the OEM number.

For comparison, Motor Trend says that when it put the 991.2 GT3 RS on the dyno in April this year, the racy-spec coupe officially rated at 520 hp turned out 420 hp on the dyno, a 17 percent loss. The 592-hp McLaren 600 LT challenging that GT3 RS in the same article returned 530 hp on the dyno, a 10.5-percent loss. So the drivetrain rule-of-thumb still applies in some places when figuring losses. Back to the 2020 911 Carrera S, working backward from the dyno figures leaves us with a car that actually produces 455 hp and 446 lb-ft at the crank on the low end, 487 hp and 478 lb-ft on the high end.

The finding comes almost exactly two months after Motor Trend put a BMW-engined 2020 Toyota Supra on the dyno and came to the same conclusion — more horsepower than expected, more torque than the coupe is officially rated to get. Car and Driver produced similar results when it tested the Supra earlier this year. BMW aficionados say the Munich brand is known for underrating its engines, an assertion backed up by C/D‘s dyno run of the current M5 Competition, getting 617 hp and 606 lb-ft at the wheels for a sedan that BMW claims gets 617 hp and 553 lb-ft. at the crank. If BMW’s fuzzy math has spread to Stuttgart, we don’t think owners will complain. At the end of the Motor Trend vid, the dyno company manager said, “It’s easy to get the 991 to 600 horsepower at the wheels, so I would expect that this car can do over 600 horsepower at the wheels fairly easily.”