While major changes are expected to happen for next year’s riding season thanks to increasingly strict Environmental Protection Agency (EPA) regulations, there are considerable advancements in 2011’s snowmobiles.
From the lightest, mass-produced 800-class mountain machine to the lowest emission two-stroke yet to power steering, the four major OEMs have produced some noteable new sleds.
Turbo or no turbo is the big question for Arctic Cat consumers seeking a four-stroke snowmobile as the OEM has added a Z1 Sno Pro to its lineup, matching the features of the Z1 Turbo Sno Pro.
Cat engineers treat these like two different machines.
Under each hood is a 1056cc, liquid-cooled, parallel-twin four-stroke from Suzuki. One version of the engine makes 123 hp while the other makes 177 hp.
The base model has power comparable to a 600-class two-stroke, but the turbo application is more of a hypersled. That means the Z1 Sno Pro and Z1 Turbo Sno Pro require differing settings.
The other big difference, of course, is price. The Z1 Sno Pro lists for $11,199, while the Z1 Turbo Sno Pro has an MSRP of $13,999. That’s certainly a big difference, but adding 54 hp any other way would likely cost a lot more, and it would void the warranty.
Polaris’ Cutting Edge Chassis
Built upon dealers’ suggestions, “Make it light, make it simple, make it work,” was the defining mantra for the Pro-RMK Chassis, says Marty Sampson, project leader for the Polaris RMKs.
The end result is a high-tech marvel in the 800 Pro-RMK 155 that’s 41 pounds lighter. It weighs just 431 pounds, making it the lightest, mass-produced 800-class mountain machine available.
Losing 6 pounds from the exhaust was nice, but the real gain came from losing 6 ounces here, 8 ounces there and 11 ounces somewhere else — and adding them all up.
“The thing that we know as a team is that if you don’t scrutinize absolutely every part you put on the thing, you’ll never get there,” Sampson said.
Examples of weight loss are everywhere. Rivets, welds, nuts and bolts were replaced with structural bonding; duplicate material in the tunnel was stamped out; steel was replaced by aluminum; the new silencer is smaller and much lighter; the plastic cover was removed from the front bumper, eliminating a couple of ounces; the rear bumper is made of carbon fiber; holes were trimmed in the snow flap.
All of this weight loss may sound simple, but there’s a lot of engineering involved. Sampson and Ripley said designing the right running board tube took six months, for example.
The rear suspension is to a mountain snowmobile what an arm is to a pitcher: It’s got to be good, or the rest doesn’t matter.
Any snowmobile rear suspension must absorb energy, but the rear suspension on a mountain sled is also tasked with grabbing traction in varying conditions; immediately pulling the machine up on top of powdery snow and defining floatation; clawing up a steep incline or through the trees; providing easy handling in powder or on hardpack; and responding to the driver’s various inputs. Therefore, Polaris engineers spent years defining and refining the RMK Coil-Over rear suspension found on the Pro RMK.
“I have a strong opinion that the rear suspension is for sure what makes a mountain sled work or not work,” Sampson said.
A lot of time was spent with various computer-assisted design programs, simulating various situations, but that could only take the designers so far.
“Computer designing is really good guidance,” Ripley said, “but without the guys with experience who have been out and done the riding, and have the experience to know how the sled reacts, the computer is almost useless.”
While the rear suspension is vital, so is a more nebulous term the RMK team refers to as “balance.”
“You achieve balance by making sure your rider’s in the right spot and interacting with the sled properly,” Sampson said. “Part of balance is about having handlebars that rotate in the right plane. So our steering posts stood up more on our mountain sleds, while they are laid down more to get out of your way in a corner on our trail-performance sleds. We stand the post up to make it more vertical, so that when you’re sidehilling or jumping or coming around on the sled and counter-steering, the bars are more square with your shoulders.”
“That’s part of the RMK DNA,” Snowmobile Product Manager Chris Wolf added. “You know, when we developed the sled, it still had to be an RMK. And balance is something that we’ve always been very proud of, it’s a characteristic of our sleds.”
Ski-Doo’s Rotax 600 ACE
It’s only a matter of time before fan-cooled, two-stroke snowmobile engines are due for extinction. With more stringent Environmental Protection Agency (EPA) standards looming that require individual model compliance instead of a fleet average, the dirtiest of the remaining two-strokes have little lifespan remaining.
Fortunately, there is a new example of an entry-level snowmobile engine that delivers comparable performance to a lightweight fan — if measured in speed and peak power output. Its other performance attributes are worthy of special attention, including nearly 30 mpg, quiet operation and claims of the lowest emissions yet from a snowmobile moved by internal combustion.
The “ACE” moniker on the new Rotax 600 ACE engine is yet another acronym, this time for Advanced Combustion Efficiency. It’s a new engine family that is available in MX Z, Renegade, GSX, Grand Touring, Tundra, Expedition and Skandic platforms.
The 600 ACE is a high-tech, 600cc, parallel twin, four-stroke with the manufacturer’s 60 hp claim. Though the Rotax 550F fan-cooled engine remains in the lineup, the ACE is destined to replace it either by mandate or consumer choice.
Efficiency was the chief target of the 600 ACE, and if the claims are true, the result of the effort is the most fuel-efficient production snowmobile engine. The 29 mpg advertised spec provides a travel range of more than 300 miles in most Ski-Doo models with the 600 ACE.
As a result of its design, Ski-Doo says its Rotax 600 ACE has high volumetric efficiency and at times result in efficiency greater than 100 percent at certain rpm.
If the 29 mpg assertion is correct, the 600 ACE is not just the mileage and range king, it also is an emissions champion. Current emissions standards from the EPA are a maximum of 75 grams of hydrocarbons (HC) and 200 grams of carbon monoxide (CO) per kilowatt hour. The 600 ACE produces just 8 HC and 90 grams of CO, according to Ski-Doo.
Rather than performance-minded riders, the 600 ACE engine family is aimed at riders who want maximum fuel economy and minimal maintenance. With that goal in mind, the engine was built with several features that require little or no maintenance.
During the presentation of the 600 ACE, Ski-Doo officials said the engine is only 13 pounds heavier than the 550 fan engine, due to the clever packaging and lightweight parts.
Yamaha’s Power Steering
The ATV models equipped with electronic power steering (EPS) are now the best-sellers in that market. But what about power steering on a sled? Following the impact of EPS on the ATV market, it has now made its way into snowmobiles thanks to Yamaha’s Apex line.
Yamaha’s system provides lighter steering and reduces the harsh feedback that normally comes through the handlebars. Also, the amount of assistance the power steering motor provides is variable, so the driver get maximum assistance when traveling at low speeds, and the level of assistance drops as speeds increase to maintain control.
The addition of power steering also allowed Yamaha engineers to make other changes to its sleds, as the company can get more aggressive up front because worries about the driver suffering from heavy steering are eliminated.
The power steering assembly found on the Yamaha Apex models comes directly from Yamaha’s Grizzly line of ATVs. Yamaha hasn’t released any official weights, but in an ATV application, the power steering motor and related assembly weighs about 15 pounds.
The twisting force of torque is measured in Newton meters (Nm), and at its peak, the Yamaha power steering motor can provide up to 22.9Nm of assistance to the steering shafts, which converts to just under 17 pound-feet. That’s input the driver doesn’t have to put in with his or her own arms and shoulders.
A side benefit of the power steering system is it not only helps turn the bars when the driver puts in inputs, it also dampens some of the harsh feedback that can come up through the handlebars. In a choppy corner, for instance, the forces that sometimes feel like they want to tear the handlebars out of your hands are absorbed by the power steering system. In the ATV market, for example, most observers actually consider that anti-kickback affect as a big, if not a bigger, benefit that the lighter steering.
Seeing what has happened in the ATV market in the past three years, and noting that every current snowmobile manufacturer builds power-steering-equipped ATVs, it’s almost impossible to envision a future without power steering on high-end snowmobiles. Such technology, however, comes at a price — the base 2011 Apex has a retail price of $13,999 — a $2,600 jump from 2009, though admittedly there’s other technology and upgrades that add to the cost.
A more fair comparison may again come from the ATV market, where manufacturers charge anywhere between $400-$1,200 for a power steering upgrade on an existing model. Yamaha charges $600 extra for a Grizzly 700 with EPS vs. a base Grizzly — and the EPS model far outsells the base model, proving that consumers value power steering. PSB