skidoos heavy breather

If you can believe the marketing hype, a press announcement in mid-September put Ski-Doo at the top of the 4-stroke food chain. Based on a firsthand impression of the Rotax four-stroke twin that was shoehorned into a rather basic MX Z-style chassis, Ski-Doo has announced the real deal.

Just in time for a debut at the first significant snowmobile show of the season (the annual Hay Day's event in the St. Paul, MN, area), Ski-Doo's marketing heavyweights unveiled snowmobiling's first V-twin, four-stroke engined sled. Introduced to the press just prior to being shipped to Hay Days, the newest player in the 4-stroke sweepstakes was unveiled in a sports chassis sled. Of course, you've seen the chassis, so the major topic of conversation, of course, was the all-new Rotax-engineered and built one-liter motor.

It is a sophisticated piece of equipment whose design features state-of-the-art automotive technology. This includes:
• overhead cams;

• four-valves per cylinder breathing;
• heated throttle body electronic fuel injection;
• an 80-degree vee design that eliminates the need for a counter-balancer;
• dry oil sump with dual oil pumps for superior lubrication;
heated oil sump;
• Bombardier TRA-clutching based drive system;
And, 80 percent reduction in hydrocarbon emissions versus a conventional 2-stroke sled engine.

This marks the first 4-stroke powerplant seen in a Ski-Doo since the early 1960s when some of the original Ski-Doo Olympiques sold in the Northeastern US were fitted with "off the shelf" Kohler 4-strokes.

Rotax' prototype V-twin was tightly fitted into the MX Z chassis which bore identification suggesting that Ski-Doo has been working on this concept for a good two seasons or more. While careful not to give away exact performance expectations, the Ski-Doo assemblage said the 4-stroke's performance and weight parameters should approximate the 2001 Ski-Doo SE. Based on that, like you, we did a little math and came up with the following estimates.

We'd figure the engine might be developing upwards of 80 horsepower in its present state of tune with on-snow performance comparable to a Legend series 500 liquid-cooled snowmobile. We figure the sled's forte will be more on acceleration than top speed at this date, but from preliminary views of the engine, we figure this design can accommodate much more power. Remember, Arctic Cat's 660cc 4-stroke delivers 45 horsepower and has a top speed nearing 60 miles per hour. Doing a little math and adding a touch extra for a more sophisticated intake and digital ignition gave us our current figure. It could readily be 10 percent up or down.

As Ski-Doo enthusiasts know, Rotax is no stranger to 4-stroke engines as it has been supplying BMW motorcycles with a 650cc single cylinder, 4-valved 4-stroke since 1993, The powerplant in the Bombardier ATV line is a 650 4-TEC design and just recently Sea-Doo unveiled a 1500cc 4-stroke drive system. Four-strokes are quite "Doo-able" for Bombardier in its recreational lines.

The new Rotax-built 4-TEC four-stroke displaces approximately 1000cc. When Ski-Doo personnel started the engine, it had a V-twin rumble more like a big Honda or Yamaha vee motor and less like a Harley. It was obvious that the engine's exhaust is yet to be finalized as the system we saw was simply a twisted set of header pipes dumping into a large silencing canister. The throttle body injection intake is rather conventional by automotive standards - and therefore should be trouble-free for sledders. This marks only the second time in recent memory that Ski-Doo has fitted a fuel injection system to a sled it was readying for production. (The other was a Ski-Doo Formula Plus that never saw actual production.)

We expect to see this sled on the snow later this winter and perhaps available for sale by 2003. Based on the quality of the engine castings and some other components, we'd suspect that the basic engine is production-ready. Once the details of exhaust and hood design are finalized, we expect Bombardier could fire up the assembly line next autumn.

The 4-TEC is said to break new ground in power-to-weight versus an inline design; provide reduced emissions; and improve fuel economy. Stay tuned for more on the all new Ski-Doo 4-TEC V1000. If you have a chance to hear one at a dealership or at an upcoming snowmobile show or other event, enjoy the hearty v-twin rumble. It's coming to a garage near you. And, soon we'd guess!