2003 bender racing turbo rx1

When Bender Racing's design wizard, Terrry Paine, dyno-tested his prototype turbo on his RX-1 base line engine, a minor error in the initial boost adjustment had the dyno operator pushing the Yamaha four stroker well past 250 hp! When Terry saw that number he yelled to shut down. At the time, he only was trying to dial in a minor four-pound pressure boost- looking for 180 hp. Only after he had the data for his base kit did he want to go looking for the big numbers. Still, based on this experience, he knew the Yamaha four liked the turbo and that his Stage 2 kit power parameter of 220 hp would be little problem for the engine. The question becomes, how much boost can the Yamaha four handle and still be reliable?

Terry says the Stage 1 kit at 180 hp is fine on pump gas. He recommends racing fuel for the Stage 2 kit and its 220 hp.

How do the two kits compare in dyno statistics? Check the dyno graph. The stock RX-1 four-cylinder motor makes 80.1 lbs/ft of torque around 7100 RPM. You'll find 140.5 hp at 9800 rpm and a best power of 141.6 hp at 10,400 revs. With a modest four-pounds of boost, torque goes to 100.3 lbs/ft at 8300 and horsepower gets to 181 at 10,500 revs. Add four more pounds of boost for the Stage 2 kit and you see 126.5 lbs/ft of torque at 7800 rpm and 222.5 hp at 10,600 revs.

This story ran in the October 2003 issue of American Snowmobiler magazine