2-STROKE VS 4-STROKE DEBATE
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.
More Like This
LATEST VIDEOS View All
Highs and Lows of the 2019 Ski-Doo Renegade Enduro 900 ACE Turbo
June 2, 2019
Following a full season of riding, AJ lays down his closing thoughts on the 2019 Renegade ...
Highs and Lows of the 2019 Ski-Doo Backcountry X-RS 850
May 31, 2019
With riding season officially over, AJ lays down his closing thoughts on the 2019 Ski-Doo ...
Highs and Lows of the 2019 Polaris 850 Switchback Assault
May 29, 2019
AJ is here to present his closing thoughts on the 2019 Polaris Switchback Assault.
Highs and Lows of the 2019 Polaris Switchback PRO-S
April 14, 2019
Following a full season of riding accumulating a ton of miles, Mark is here to lay down his ...
Highs and Lows of the 2020 Ski-Doo Expedition Xtreme
April 13, 2019
With the 2018-2019 winter season ending, Motorhead Mark is here to give you his closing thoughts ...
Top Gear View All
March 26, 2019
NEW CKX MISSION HELMET
Panoramic views combined with advanced air management technology.
Ask Motorhead View All
April 3, 2019
NOT HAPPY WITH SHOOTOUT RESULTS
Luke responds to a viewer's disappointment about the results of our 600-class, 129-inch shootout.
Press Releases View All
April 2, 2019
2019 REVOLUTIONARY ADVANCED DESIGN AWARD
Trax Media Inc. and SnowTrax Television are pleased to announce the winner of the prestigious 2019 Revolutionary Advanced Design Award ...