A Thousand Points of Power

With so much new, where do you start? Well, duh, the engine, of course. Not since the triple-cylinder Thundercat has the snowmobile industry had a stock two-stroke 1000cc thumper to satisfy horsepower hungry riders. Okay, let's be honest here. It's really a 998cc engine.

"It's all about power and more power," Jean-Francois Guertin, Ski-Doo director of marketing, said in reference to the new Rotax 1000, which has 25 more horses than Ski-Doo's 800 H.O. "This is the mother of all Rotax engines."

Two key features of the Rotax 1000 include semi-direct injection and electronically activated eRave exhaust valves. Those two nifty features help this monster motor crank out 165 hp. The SDI has two injectors per cylinder-one small and one large-going into the transfer ports. The small injector, which operates alone at low rpm, is easier to calibrate and extremely stable, for a smooth idle. At higher rpm, the large injector begins working along with the smaller one for maximum power output.

This new SDI has made the Rotax 1000 compliant to the EPA's 2006 emissions requirements. As for the eRave exhaust valves, they control both the primary and secondary exhaust ports which provide improved gains in performance and reduced emissions. For added precision, the exhaust valves are opened and closed with a smart stepper motor, rather than exhaust or crankcase pressure. And, according to Ski-Doo engineers, the communication between the Engine Control Module (ECM) and stepper motor is two-way, which means the ECM changes the ignition timing map only when the valves are actually opened or closed.

Because of the real potential for an engine this size to have some vibration, Ski-Doo uses two unique balancing gears rather than a heavy balance shaft. Each cylinder has its own asymmetrical gear, run off the crankshaft.

Other engine features include: crank positions sensor, atmospheric pressure sensor, throttle position sensor, knock sensor, ambient temperature sensor, engine temperature sensor and pipe temperature sensor. The ECM monitors all these inputs and changes ignition timing, fuel-to-air mix and exhaust valve operation to get the maximum performance. Other engine tidbits include a water-cooled engine base, as well as the removable compression domes being water cooled. To keep this big motor cool, Ski-Doo has increased coolant flow to 10L per minute. The coolant enters through the bottom of the engine and exits through the top right because of its backward tilt. Interestingly, the 2-Tec 1000 is mounted to the RT frame from its sides, as opposed to the bottom. This helps reduce the vibration and keeps the center of gravity where it should be on a sled, close to the driver.

This new engine also has two separate air boxes. The primary airbox is similar to the Rev design and has two tubes to deaden sound while the secondary airbox is mounted on the side panel, like on a Rev, and has a quick disconnect between it and the primary airbox. This secondary airbox holds the belt and spark plugs.

The new Rotax 2-Tec 1000 was a wee bit big for the Rev chassis so Ski-Doo had to go to the drawing board to create a bigger belly. Thus the RT was created. The RT has been in development for three years and Ski-Doo officials insist it's not a Rev stretched out. It's new from the ground up.

"Basically, we took what we learned through the development and production of the Rev and created the next evolution of the concept," Steve Langlais, Ski-Doo engineering project manager, said. In designing the RT, Ski-Doo did want to keep many Rev platform characteristics, like driver-centered ergonomics, the RAS front suspension and pyramidal frame, among other things. One thing that did change on the RT, compared to the Rev, was increasing the wheel base by two inches. The driver has also been moved back two inches. Those changes make for a more relaxed rider position as well as reduces drag and increases straightline ability. The driver on the RT is still 10 inches more forward than a conventional snowmobile. The looks (a.k.a. styling) of the RT do resemble that of a Rev.

A cool design element of the RT is the front heat exchanger, which has been engineered as a key part to the chassis' torsional rigidity. The exchanger has a two-part design. The upper half provides enough cooling for speeds up to 50 km/h while for speeds above that (which is where we think the Mach Z will be running most of the time), the bottom half of the exchanger has capacity and cooling fins for additional capability. Because of the Rotax 1000's design and advanced computer technology Ski-Doo was able to eliminate the cooling system's thermostat. On previous thermostat-based systems, coolant warmed by the engine was routed right back to the engine to help heat the block. Once the engine was running at an optimum temperature, the thermostat opened up and ran the coolant through the heat exchangers. The RT and 2 Tec 1000's computer system limits rpm until the temperature sensor says the engine is warm enough. And since 2 Tec engines run hotter than carb models, the warm up occurs pretty fast.

You're kind of getting impatient waiting for us to get to the mountain stuff, huh? Hang on campers, there are a couple of more features the Mach Z and Summit share. One is the new TRA V clutch, a necessity on the more powerful Rotax 1000. So, obviously, the TRA V primary features increased durability, including a 50 percent stronger governor cup and stronger spring cover. Because the clutch had to handle higher loads, the levers needed to be reinforced and made heavier. The TRA V levers are steel (not aluminum) but weight was saved through an optimized lever design.

Another new drivetrain component is the RT chaincase, which uses a Borg Warner chain, improving efficiency by 1.5 percent because of its rocker joint-type (no rollers) design. The chain promotes cooler chaincase temperatures. A 45-tooth bottom gear and 29-tooth top gear are standard. The Summit case is one inch longer than the Mach version, which provides more tunnel clearance for higher profile tracks. The Summit also still uses a tensioner, whereas the Mach Z doesn't need one.

We didn't get any saddle time on the Summit Highmark before this magazine went to press but we rode the Mach Z and whew . it can blister any lake or trail. We thought the Mach Z was surprisingly stable on the trail and really did eat up the bumps we found, although the trail was in decent shape and not mined out. The most telling feature of the Mach Z was when we took it across a frozen Quebec lake. Stump-pulling torque and dripping with power. The ante in the muscle sled trail group just went up.

Now for the features that the new Summit Highmark doesn't share with the Mach Z. The most obvious would be the PowderMax track. The in season Summit Highmark will come standard with a 16x159x2.25 inch track. Remember our math lesson from a season ago, when Ski-Doo first introduced the 16-inch wide track? A 16x144 has about the same footprint as a 15x151. A 16x151 has about the same coverage as a 15x159. If you can't get the highmark with this Rotax 1000 and PowerMax track, well . take up knitting because you won't live that down.