Motor Trend dyno tests the C8 Chevy Corvette and discover that the output might be considerably higher than advertised.
This is not an unusual discovery nowadays. There are numerous recent examples of modern cars putting down larger numbers than what the spec sheet says. Earlier this year, it was “discovered” that the new Toyota Supra produces far more power than Toyota says following a dyno test. In this instance, it’s the new 2020 C8 Chevrolet Corvette that, according to Motor Trend, is far more gifted than GM says.
The story goes that once they were done with the C8 after Car of the Year testing, the guys decided to dyno-test the mid-engine beast to see what’s what. After figuring out which gear to use and doing a few runs, the results were staggering with up to 561-horsepower and 523 lb.-ft. of torque at the wheels (highest numbers recorded during the testing, not necessarily during the same run). The typical quick math to figure out output at the crank involves calculating a 15% drivetrain loss. In other words, up to 660-horsepower and 615 lb.-ft. of torque. Can this be?
According to one of our absolute favorite auto critics, Jason Cammisa, no, it’s not possible. We won’t paraphrase his explanation as it’s quite complete. He wrote on Instagram:
“The C8 Corvette Stingray does NOT make 650 hp!
A certain media outlet published a story today that they dyno’ed one and got more than 500 hp at the wheels… calculating back to 650 hp at the crank.
This isn’t possible. 650 hp from 6.2 liters of displacement can’t happen with at only 6500 rpm without forced induction.
Horsepower is a function of torque x rpm… and there’s a maximum torque-per-displacement (otherwise known as BMEP, or Brake Mean Effective Pressure) that’s vastly exceeded by Motor Trend’s dyno runs.
MT’s 630 lb-ft number suggests the LT2 makes 17.2 bar BMEP. The most efficient naturally aspirated engines are around 13. The LT2 is SAE rated at 12.9.
Did it have turbos on it that no one saw? I suspect not… but they sure didn’t show up in acceleration testing…
Here’s the real reason I know the dyno results are invalid. See the screenshot on image 2.
This is my acceleration simulator. My nerdiness knows no boundaries, but I’ve been using this calculator since the early 1990s.
I inputted a DynoJet plot from a 7-speed manual Z51 C7 I found on the Internet… 417 hp and 415 lb-ft at the wheels. Then I plugged in the C8’s actual weight, gearing, tire size, and I estimated drag coefficient and frontal area.
The numbers (in black, on the right) line up almost exactly with the testing results @roadandtrack got (in red) – within ~0.3s all the way to 150 mph.
The most damning is top speed, which calculates to 182 mph. Chevrolet claims 184 mph for the Z51 C8. I’d expect a couple mph higher with the C8’s LT2 engine (495 hp instead of the C7’s 460 that I used here.)
If the thing really made 650 hp, top speed would be vastly higher. Like, 200+ mph.
MT’s dyno piece doesn’t pass science muster. I’m disappointed that they published it — something was clearly broken on that dyno. They should have brought it elsewhere and re-tested.
Or at least realized that the numbers didn’t line up with the reality of their tests.”
We think that Jason’s right. At the very least, Motor Trend should have brought the car to another dyno to compare results. In MT’s video, they call upon C8 owners to allow them to test their cars on the same dyno as well…
What do you all think?