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As if I haven’t penned enough editorials on the subject of 2 and 4-strokes’ weaknesses and strengths, here we go again!

Actually, you can blame Ski-Doo and Rotax for this diatribe. It was Ski-Doo and its Rotax engine division that blew the lid off the whole “good motor – bad motor” argument in MY17.

You heard it, we heard it: Ski-Doo made the outlandish statement its new Rotax 850 2-stroke, the powerplant of the future for the all-new G4 chassis, would deliver durability rivaling an equivalent 4-stroke.

I don’t know about you but when I first heard this claim at the intro of the G4 in Riviere Du Loup, Quebec in January 2016, I was pumped. I am a bald faced proponent of 2-strokes. In my view, they are truly “snowmobile-centric” powerplants.

Conversely, 2-strokes are being replaced in virtually every other powersport genre by 4-stroke engines. Still, in our sport, the inherent advantages of 2-strokes are so compelling, investment in 2-stroke engine technology continues. Need proof? Polaris’ 800 HO, Arctic Cat’s DSI 600 and 800 and, of course, Ski-Doo’s successful E-TEC duo.

That’s not to say I’m anti-4-stroke. New stuff in the market like the imposing Yamaha/Arctic Cat turbocharged and intercooled 998cc triple definitely ignites my testosterone on an acetylene torch heat level. There are other 4-stroke engines that capture my interest no matter how much I resist, however, when they’re compared to similar output 2-strokes, in the back of my mind I’m thinking: “Why bother?”.

Lately, I’ve taken the opportunity to ask a number of movers and shakers in the engineering world what they perceive the future of snowmobile 2-strokes engines might look like.

One I asked is Rotax VP, Thomas Uhr, on a recent trip to Rotax’s home in Gunskirchen, Austria. Thomas is an insightful and likeable guy who answered my inquiry about the future of 2-strokes with this succinct and insightful quote: The 2-stroke engine is far from dead”!

The issues Rotax addressed that ultimately allowed Ski-Doo to make the almost outlandish claim of 4-stroke durability, when examined closely, make sense.

The 850 uses a forged crank, automotive in nature, and employs cast iron ring lands in its forged aluminum pistons: Diesel engine stuff. The 850 has pinpoint oiling nozzles shooting lubrication under the piston to the small end of the rods. This addresses a decades-old 2-stroke weakness. These features, when rolled together, make the Ski-Doo claim of 4-stroke durability entirely credible.

Despite the argument I’ve made for continued 2-stroke power in sleds, there are limitations. It’s pretty clear ultimate performance turbocharged snowmobile engines producing 180 to 200-horsepower in MY18 are the exclusive domain of 4-strokes.

Turbocharging 2-strokes, although possible, is not likely to happen in today’s world of EPA mandated exhaust emissions. The very nature of pressurized induction, whether achieved with an exhaust driven turbo or a gear driven supercharger, pushes too much unburned fuel charge out the 2-stroke’s exhaust port before the rising piston can close it off. The result is hopelessly dirty emissions. Yes, 2-stroke turbos do exist but none are consumer-available on production powersport engines.

I think snowmobile buyers value the inbred traits of both 2-strokes and 4-strokes using solid knowledge to make their purchase decisions. 2-stroke buyers appreciate light weight, low maintenance and imposing power-to-weight ratios. Many 4-stroke buyers line up behind the reliability-durability flag and appreciate not carrying oil when on tour.

What’s confounding is the amazing fuel economy Ski-Doo’s E-TEC 2-strokes consistently card. Arctic Cat’s Dual Stage Injection (DSI) 2-stroke also delivers strong mpg. Up until the arrival of the Ski-Doo ACE 4-strokes, the best fuel economy in any horsepower category was attributed to the Rotax 600 E-TEC.

Here’s the good news: It looks like this debate will rage on for some time to come. If Thomas Uhr is correct – and I wouldn’t bet against him – we should be enjoying 2-stroke power with improved durability for some time.

Mark Lester
Mark Lester
Mark Lester is Co-Publisher of SUPERTRAX Magazine and a regular Host on SNOWTRAX TV, which can be seen on Sportsman Channel across America and in Canada on OLN, Sportsman Channel Canada, Wild TV and REV TV and globally on our YouTube channel.

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