Reply To: Jansen destroys Rotax in record time?

[Brad Linkus]

At our altitude the engine produces 23% less power than at sea level so there is 23% less stress. It is true you use less fuel but the engine does not run leaner as the optimum fuel to air ratio is the same at any altitude. The ratio of oil to gas is the same so the engine does not get less lubrication. On the other hand if you go off the track regularly and suck dirt into the engine through the lousy air filter the Rotax has this will cause accelerated bearing and piston wear. All it takes is one small piece of dirt to stop the lower end bearing from turning. In just one second the crank pin will turn over 200 times against a stopped bearing which will flat spot the rollers and fry the bottom end. All of the power (load) goes through that bearing. If you look at the design life chart for a roller bearing of that size using the rpm the engine runs it is not even on the scale to determine hours of expected life. Race engines exceed the normal design rpm operating limit of bearings so the life of the bearing is limited.