Just after the ports get covered by the piston a HIGH pressure injector squirts fuel directly into the compression chamber. Thus the is no possibility of fuel escaping out the exhaust. Problem is that you only have about 15 degrees of crank rotation to do this before the spark. so everthing has to be timed just right.
I can see it coming though. All outboard manufacturers are doing it at around 6500 rpm. And if the outboard can do it so should a sled engine.
A couple of years ago I posted this question to an engineer behind the FICHT injections system which Cat has licensed rights to. Direct injection will work on the higher reving snowmobile engines, you will get better fuel economy, less oil usage, and less pollution. Doo has a semi direct injection out this year and I see the others jumping to DI technology soon. It is a good alternative to 4 stroke engines for us sledders.
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