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Mick Rupp earned fame as a "motorsportsman" in the 1960s and by the 1970s he had earned a reputation for creating high-performance snowmobiles.
Just as his automotive pursuits were built around speed and performance, so too were his sleds.
With snowmobile racing stalwart Gene Bloom helping to create a Rupp performance persona at the race tracks of the snow belt, the Mansfield, Ohio-based snowmobile brand delivered both styling that was "ahead of the curve," and speed. By 1976 one of the sleekest and sexiest sleds in the business was the new Nitro 440.
Under that stylish hood was a hot new powerplant from Fuji Heavy Industries' parent company, Xenoah.
If that name sounds familiar, it should. It was that same firm that built the performance-oriented liquid-cooled twins for the highly regarded 1974 Chaparral SSX.
When Chaparral's parent, Armco Steel, pulled the plug on its Denver-based snowmobile company, Rupp stepped in and cut a deal for the engines. With two years extra development time, the Nitro featured Rupp's specifications and greater durability.
The Xenoah was a bit over-engineered by standards of the day. The crankshaft bearings were beefed up to withstand the high performance requirements demanded by Rupp engineers.
That standard meant the 440cc version could hit a top speed of 80 mph in the quarter-mile. That was the best of all 26 models tested by a snowmobile publication that season. And that was at altitude in Colorado. And that was a full 7 mph faster than the next best high-performance model!
The Rupp Nitro 440's Xenoah twin featured a reed valve intake that ensured more of the fuel charge was fed to the combustion chamber.
More unusual was the use of an automotive-style radiator for cooling. An automotive-type, pulley-driven water pump and thermostat helped to manage consistent cooling temperatures.
Another unique feature of the Nitro cooling system was the use of the front bumper assembly as a cooling coil. Coolant ran through a hollow space in the bumper, which could be further cooled by both snow and cold winter air.
With its twin-piped engine enclosed, the Nitro required all the engine cooling it could muster. But engineers claimed that it was sufficient, even for periods of slow speed riding and idling.
The engine also featured Arctic Cat's El Tigre roller ramp drive clutch and complementary driven. The jackshaft was borrowed from Cat as well and required Rupp engineers to totally revamp the front end.
The Rupp Nitro's new engine was tilted back and lowered in the engine compartment for a low center of gravity and more precise on-trail maneuverability.
Likewise, the spindles' geometry was changed for more nimble handling, making steering easier and enhancing the sled's ski stance.
Under the aluminum tunnel you would find a 16.5-inch involute drive circling a set of Rupp Rails, a proprietary slide suspension design. Up front were shock-assisted leaf sprung skis.
Having enjoyed a winter's worth of riding aboard the Nitro 440's smaller 340cc sibling, I can attest to the excellent on-trail performance of this model. It was one of 1976's best handling machines. At just more than 400 pounds, the Nitro series was an easy handling high-performance sled.
With a base price of $1,895.00, the Rupp Nitro 440 may have been in the upper bracket for snowmobiles in 1976, but so was its performance.
And that's always worth a little extra. Isn't it?