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Early claims by Polaris said the new Cleanfire Liberty engine would produce about an 11% increase in horsepower compared with the 800 Polaris twin. Our technical editor Olav Aaen determined in this season's premier issue, the AmSnow Buyer's Guide, that such a gain would translate to between 146 and 151 hp at 7500 rpm. He figured this by comparing it to a standard Polaris 800, which usually produces 132-136 hp at 7600-7700 rpm. As usual, he was pretty darned close with his figuring!
Both Rich and our AmSnow staff have been impressed with the early showing of the detonation control engineering on the new Fusion. The knock sensor feature in the Fusion can sense the fuel grade used and can adjust automatically. If a knock begins, the sensor will back the engine off to a lower ignition curve and richen the mixture in less than a second. This is extremely helpful on those really long trail rides when higher-octane fuels aren't always available or a filling station may have old gas.
Polaris has had a few glitches in getting the big new Fusion twin to market, but Rich's numbers prove the Minnesota-based sled maker was honest in its evaluations of the new Cleanfire 866cc engine's performance capabilities. Horsepower for this 500-lb. sled is big and stable with plenty of torque at low rpm.
This story appeared in the February 2005 issue of American Snowmobiler