It was one of those days where you forget to think. We had just finished strapping the 2011 Mercedes-Benz SLS AMG down to the dyno when we realized we didn't have our video equipment with us. Damn.
Although we didn't capture the glorious aural crescendo of the AMG's dry-sumped 6.2-liter DOHC V8 as it soared toward seven thousand revs, we got the dirty work done. The rollers of the Dynojet 248 chassis dyno would reveal the potency and character of this normally aspirated, 32-valve bent eight.
The SLS' power plant -- engine code M159 -- is a special one. Starting with the "base" 6.2-liter M156 V8 that's found in every AMG model with a "63" in its name, power-hungry German engineers then redesigned the intake tract, added more potent cams and installed freer-flowing exhaust manifolds. They then dry-sumped the thing, called it the M159 and stuffed it way, way aft of the gullwinged coupe's front wheels.
Oh, and in the process, they liberated some power. Mercedes-Benz rates the M159 V8 at 563 horsepower at 6,800 rpm and 479 lb-ft of torque at 4,750 rpm. That's what it makes at the crank, and it's some 40 hp stronger than the "lowly" M156.
At the wheels, here's what we measured (3% weather correction applied):
Yup, she's a stout one. Peak torque of 447 lb-ft was recorded at 4,900 rpm, and peak power of 527 horsepower was reached right at the 6,850-rpm fuel cut. When you factor in driveline loss, this bird is making at least what Benz claims, and likely more.
This is without question one of -- if not the -- most powerful normally-aspirated series-production V8s on the planet. If you're still in doubt, check out the quarter-mile performance of the SLS we tested.
Note that power is still on an upward tack even as it runs out of revs -- this indicates that the big mill's apparently got the lungs to support an even higher rev limit. Typically, production normally aspirated engines reach peak power and then check out entirely in the last few hundred revs.
This one's power output, however, is limited by the revs it can turn and not the airflow it can take in. For best results, shift it as close to the fuel cut as you dare. Pretty cool.
And the sound it makes? Yeah, pretty epic. Next time, we'll bring our video gear. We promise.