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I Took My Dodge Viper to the Dyno to See How Much Horsepower It Makes

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author photo by Doug DeMuro June 2017

I recently had the bright idea to take my Dodge Viper to a dyno in order to measure how much horsepower it has. When I say, "I had the bright idea," what I mean is that my new friends, Chip and Matt, from Matt Hill Motorsports in southern New Jersey, e-mailed me and asked if I wanted to get my Viper on the dyno. I had little to do that day aside from stage a fight between my stuffed tapir and my stuffed beluga whale, so I said yes.

And so, I put the Viper on the dyno, and by "I put the Viper on the dyno," what I really mean is that Chip carefully backed the Viper onto the dyno, and Matt secured it using large straps that looked like they could've kept that Tyrannosaurus rex from terrorizing San Diego in the second "Jurassic Park" film, and I basically stood around like an idiot, pretending I was setting up my camera equipment.

So then it was time to actually bring the Viper onto the dyno. Now, before I get into the actual numbers and what happened next, let's discuss the Viper's stated numbers. According to Dodge, my Viper GTS made 450 horsepower and 490 lb-ft of torque back when it was new in 1997. However, these numbers account for the car's "brake" horsepower -- at the engine's brake -- whereas the dyno measures "wheel" horsepower -- at the actual wheels. There's always some horsepower loss between the engine and the wheels, and the general view is that it's about 15 percent. And so, in order for the Viper to be making its original, 450 brake horsepower, it would've had to put down 382.5 wheel horsepower.

I really didn't think this was going to happen. Here's why: I like my Viper, and my Viper has been well-maintained, but my Viper also came out of 1990s Chrysler, which wasn't exactly known for its tremendous build quality and its precision when it came to things like number of horsepower, and number of torque, and number of wheels each car had when they left the factory. So while I figured it probably made 450 horsepower at one point, 20 years ago, it likely wasn't pulling down that number today.

So I got inside, and I put on my seat belt for the first dyno run, and I experienced the single most bizarre experience you can get in a car: accelerating fairly quickly and going through the gears, while staring at a garage door and not moving an inch. This was so disorienting that I forgot to floor the accelerator in fourth gear on the first run, and I ended up with 215 wheel horsepower. We'll call that one a "practice." Yeah. That's what it was.

Next up was my first real run. Back inside, shifting gears, disorienting feeling, and then I punched it in fourth, all the way to the rev limiter. This was the fastest I've ever driven the Viper -- way above triple digits -- even though I was sitting still. For someone who's only been on a dyno three times, this is tremendously nerve-wracking: You can't help but wonder if the car's going to break, or if the roller is going to break, or if the whole thing is going to explode, especially because the sound of all this is absolutely deafening, especially as the car starts to get higher in the rev range.

Anyway, with that run out of the way, I did run number two, and then run number three, and then run number four -- all equally disorienting and scary -- and then I got out to check the numbers. And they were ...

Well, the best horsepower run was really impressive: 398.32 wheel horsepower, which is right around 469 brake horsepower. The remaining runs were all right in the same area: 398.14, 394.17 and 396.58. In other words: While I thought some embarrassing amount of horsepower had probably escaped from this car over the years, the result was quite the opposite. My Viper is more powerful than Dodge said it was back in 1997, suggesting that either my Viper is special, or Dodge was a little conservative with the power rating. I suspect it's the latter.

Torque, interestingly, was the same: Dodge initially claimed the Viper made 490 lb-ft of torque, and my Viper hit a maximum of 437.36 lb-ft. Using the same "15-percent loss" calculation, I arrive at roughly 515 lb-ft of torque where Dodge measures it -- once again, better than the initial number. With that said, torque dropped off more substantially throughout my runs than horsepower -- but even my last dyno run measured more torque than the factory, hitting 422.9 lb-ft at the wheels, or roughly 498 at the brake.

And so, ladies and gentlemen, now we know the answer: Going by the maximums, my Viper makes about 470 horsepower and about 515 lb-ft of torque -- and that makes it even scarier than you all thought it was back when Dodge told you how much power was under the hood.

Doug DeMuro is an automotive journalist who has written for many online and magazine publications. He once owned a Nissan Cube and a Ferrari 360 Modena. At the same time.

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I Took My Dodge Viper to the Dyno to See How Much Horsepower It Makes - Autotrader