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American Snowmobiler was the first to have a confirmed third party dyno report on the highly anticipated 2008 Yamaha Nytro back in April! We posted the results on our Web site then, but figured some of you may have missed them, being just after the season and all. So here's what we found.
The power-makerSnocross blood runs through the veins of this 1049cc 3-cylinder, open loop fuel-injected, liquid engine. The Genesis 130 also is designed to run best on 87-octane fuel, good news for riders who often find themselves in rural places where higher octane is not always available. The engine also weighs 10.2 lbs. less than the Genesis 120 found in the Vector and Venture. Bore and stroke on the Nytro are 82 and 66.2 respectively.
Initial snow testing of this powerplant provided us a chance to feel firsthand the incredibly strong, and long, pull this sled has out of the hole, right up through the top end. No wonder it was able to rocket out of the corners on the WPSA snocross tracks last season. Some of that throttle response is due to a new, lighter, more responsive and durable crankshaft. The shaft is 1.7 lbs. lighter than the Vector's, and that makes a difference when reducing rotating mass.
The radiator sits above the engine and rearward of the headlight, and there are plastic formed channels constantly directing fresh air through the radiator to keep cooling this 4-stroke. Unlike the 120 and 150 engines from Yamaha, the Nytro uses a straight exhaust pipe design that exits as a single out the sled's back end. The exhaust maximizes horsepower, dissipates heat and helps centralize the sled's mass.
ShockingTesting was conducted by
AmSnow's Technical Editor Olav Aaen, owner of Aaen Performance. For a side-by-side comparison, Aaen also dynoed Yamaha's Genesis 120 engine the same day.
Nytro's power outperformed our expectations and should prove to any non-believers that the pull we talked about after our first prototype rides really was that strong. The numbers tell the story of a 138.6-horsepower brute that hits with a ton of torque. Peak horsepower was made at 8,500 rpm and a top torque number of 94 foot-pounds was recorded near the bottom end at 7,100 rpm.
Compare those numbers to the Genesis 120 that showed a high horsepower number of 122.6 at 8,400 rpm and a top torque number of 83.4 ft.-lbs. at 7,500 rpm. That's a full 16-horse gain! Not to mention that the Nytro hits harder off the line, which is where you want the most torque.
To get a better feel for these numbers, we looked at comparable 800cc and 700cc sleds that we've had Rich Daly at Dynoport test for past issues. The Arctic Cat F8 showed 143.7 hp at 7,700 rpm and 99.9 ft.-lbs. of torque at 7,500 rpm. The Ski-Doo 800 PowerTEK engine delivered a top of 140 hp and 94 ft.-lbs. of torque. While the F8 and Doo 800 certainly have higher horsepower and torque numbers, it's important to keep in mind that the Nytro has a much broader power band. Yamaha 4-strokes have long legs and keep winding out.
Comparing the Nytro to Cat's old F7 - which was a stunner in engine performance - we see it dialed up 140.1 horses. Polaris' Dragon 700 is pushing a solid 140 hp at peak rpm. While both of these 700s hold a higher horsepower rank, neither has the put-you-in-the-backseat torque of Nytro.
Final thoughtRightly, power-to-weight has been the talk of the town this year, and with the high-horsepower, super-lightweight 800 race engine from Ski-Doo, and a new huge horsepower 800 from Polaris, you can understand why.
To give you a glimpse, when you do the dry weight math, the Nytro has .26 hp per pound. Last year's 2007 Cat F8 had .28 hp per pound, which was still less than the 2007 Polaris Dragon at .285 hp per pound, which was trumped by the 2007 Ski-Doo Blizzard with .29 hp per pound. None of these '07s could match the old F7 at .30 hp per pound.
To add more fuel to the fire, none of the aforementioned sleds will even come close to the brand new 2008 Ski-Doo 800 REV-XP or 2008 Polaris Dragon 800 as far as power-to-weight is concerned.
Here's something for you to ponder though: with all this talk about lightweight and huge horsepower being the No. 1 priority, how was Robbie Malinoski able to win the national snocross at Brainerd, or place as well as he did throughout his year on a Nytro? Shouldn't he have been dead last? Food for thought.