Overview
Even after five seasons, the Ski-Doo REV platform is still the benchmark in the snowmobile industry. Many have even asked, “How can they make it better?”
Soon after the debut of the REV, BRP product planners asked the same question. They came up with three objectives:
1. Set a new industry benchmark for light weight
2. Develop a more flexible riding position – from more athletic to more relaxed
3. Improve on the REV, especially long ride comfort, wind protection, top speed, fit/finish and gauges
The result is the new Ski-Doo REV-XP platform, the basis for 2008 MX Z and Summit models.
More than just a refresh, the REV-XP is a ski to track redesign. Nearly every single element was redesigned for lighter weight and better performance. Besides engines, the new platform shares only a handful of parts with the REV, most notably skis and handlebar controls. Even the pull-start handle was redesigned – and removed on vehicles with electric start – to save precious grams!
Engineers and designers started with basic concepts from the REV architecture – driver-forward ergonomics, centralized masses, pyramidal frame, A-arm front suspension – and began redesigning and re-imagining.
Light weight
With all the efforts to reduce the weight of snowmobiles over the past 10 years, such as replacing steel with aluminum, there are no longer any “silver bullets” for weight reductions at reasonable cost. Significant reductions must come from shaving grams everywhere. Maybe that’s why recent competitive platforms are all heavier than their predecessors.
With the Ski-Doo REV-XP platform, BRP engineers redesigned the entire snowmobile to reduce weight – without compromising durability or performance. If fact the REV-XP chassis is 37% more rigid than the REV chassis.
The result is an incredible 11% (51 pound – 23 kg) reduction in vehicle weight, with an increase in strength and durability. Consider how the popular MX Z Adrenaline 600 H.O. SDI model compares:
| Model | Weight | Difference | % Difference |
| ’08 MX Z Adrenaline 600 H.O. SDI | 428 | | |
| ’07 MX Z Blizzard 600 H.O. SDI | 479 | +51 | 11% |
| ’07 Arctic Cat F6 | 498 | +70 | 14% |
| ’07 Polaris 600 H.O. IQ CFI | 485 | +57 | 12% |
| ’07 Yamaha Nytro | 533 | +105 | 20% |
BRP engineers optimized the function, shape and materials of each system and part with computer designs. Cutting-edge computer analysis techniques, for instance, enabled chassis engineers to determine the lightest aluminum tube diameter/wall thickness that would meet strength targets. In other cases, engineers came up with solutions to combine parts or use new alloys and materials. The is chassis designed for tension and compression rather than flexion, and brings all forces to a point. Many cast aluminum components are manufactured through a Low Pressure Permanent Mold process.
| REV-XP vs. REV Weight Reduction by System |
| | Trail | Mountain |
| Chassis | 13 | 14 |
| Front Suspension | 7 | 6 |
| Rear Suspension | 8 | 9 |
| Steering system | 5 | 5 |
| Track | 4 | 6 |
| Driveline | 8 | 8 |
| Body, seat | 8 | 6 |
What it means to snowmobilers: After obsessing over light weight for years, industry buzz has died down with the introduction of ever heavier competitive snowmobiles (One might expect to read “You can’t even feel this is a 600 pound snowmobile!”).
Ski-Doo REV-XP platform-based sleds will bring light weight back into the conversation, as riders will feel how light they are. That’s because light weight is more than a number. Lighter weight translates to benefits such as:
· More fun, a more connected ride, as body inputs produce bigger response
· Less effort, less fatigue at the end of the day
· Better fuel economy, longer range
· Quicker acceleration, better top speed
· Better flotation, more forgiving in deep snow
· Easier to load/unload, move around
Weight Reduction Example: Chassis FEA Analysis/Racing
 | Chassis optimization was critical to the REV-XP project, not just because of the possible weight reduction, but because any reductions could not come at the expense of strength and durability. Key to making the chassis light weight without sacrificing durability was Finite Element Analysis (FEA) evaluations. FEA enables engineers to “stress test” parts on the computer – individually, and in the context of the entire chassis system. |
Once several computer designs were complete, BRP engineers built a REV-XP prototype.
They attached electronic sensors to each and every chassis part that measure the stress on the part by measuring changes in its electrical resistance. All these sensors were connected to a laptop computer.
By actually riding this prototype, BRP engineers would acquire data on how much stress each part would endure during real conditions. Each part’s maximum stress during this testing would become the benchmark for further design refinements.
Who better to determine a snowmobile’s limits than professional snocross racers? A select group of Ski-Doo X-Team riders, including Blair Morgan and Steve Martin, put the sensor-equipped REV-XP prototype through its paces on a track during private testing sessions. The racers were asked to be harder on the sled than usual – even intentionally “casing” several landings.
"This new chassis allows you to jump and run lines you wouldn't even attempt on the REV – the improvement is that big," said Blair Morgan, pro snocross racer. "And the improvement in cornering is huge."
With stress baselines for each chassis part, engineers could now use the FEA process to refine the design or materials to meet the toughest standard for durability and light weight. For example, they could experiment with different aluminum tubing, varying the tube diameter and wall thickness, until they found the perfect combination that would hold up under extreme race conditions – all without building endless physical prototypes.
The result is a chassis that is 17 percent lighter, while 37% stronger.
Weight Reduction Example: Steering System
 | The REV steering system had significant potential weight savings, at 13.5 pounds (6.1 kg) and 133 parts. BRP engineers replaced the rack and pinion system with a simpler, 33 part system on the REV-XP. One drawback was that the geometry of the new system could cause bump steer if designed poorly – an unacceptable step back in performance. Using sophisticated computer design software, engineers designed the bump steer out of the front suspension – the forged ski spindle changes caster angle as it moves through the travel and the ball joints are not stacked in the same vertical plane. In addition to the 35% weight savings (five pounds – 2.3 kg) – the system is tighter, has more response, more feel, and a tighter turning radius. |
Weight Reduction Example: Hydroformed Drive Shaft
Flexible Riding Position
In terms of riding position, BRP decided that rather than just making it more comfortable for longer-legged or touring-style riders, it would also push the edge of performance riding.
 | By moving the secondary clutch and jackshaft from beside the tunnel to above the tunnel – the Over-Tunnel Drive (OTD) – designers added eight inches (20 cm) of legroom for easier cornering and better bump isolation. The rider's feet can now be used even more to influence control of the sled. Raising the driver one inch (2.5 cm) increased the shin-to-thigh angle for added comfort. |
Designers also minimized the cab and fuel tank area, so there’s more forward room for aggressive or mountain riding. Trail riders can really get forward and hang off the inside for assertive cornering – it’s easier to break the track loose and slide while keeping the machine flat.
For powder riding, the additional forward room and 1-inch (2.5 cm) wider running boards makes REV-XP/Summit sleds incredibly easy to move around on and more responsive. Both trail and mountain riders will appreciate the smooth surface of the rear of the cab – it is easier on knees and shins. For even more flexibility, all REV-XP-based models will feature riser blocks, enabling riders to tilt and roll the handlebars for best fit and riding style. Several different blocks of various heights are available as accessories for further customization. |  |
What it means to snowmobilers: With the REV-XP, all the benefits of driver-centered ergonomics and centralized masses that made the REV platform second-to-none are made better – cornering response, powder maneuverability, riding effort and bump isolation – plus riders can stretch out their legs.
Riders can get up on the bars and corner like a cross-country or snocross racer, run the bumps with ease then stretch out and cruise while waiting for everyone else to catch up – all without making mechanical adjustments.
Styling
Such a radical redesign of the snowmobile requires a radical look. And with the significant weight reduction, the sled had to look as light as it is. BRP designers accomplished both by tightly wrapping the mechanical package with sharply intersecting planes.
The style, called “facetised” design (as in the facets of a diamond), is inspired by stealth aircraft and high technology products. The look is fresh, as product design (especially automotive) is still generally organic and geometric.
Even though the REV-XP style is cutting edge and forward-looking, designers included the BRP and Ski-Doo DNA that make a Ski-Doo snowmobile a Ski-Doo snowmobile, such as overall positive curves, a directional wedge profile, converging frontal lines (V-hood) and an emotional facial expression.
Facetised, “stealth”-inspired design Ski-Doo DNA: Emotional facial expression
Ski-Doo DNA: Positive curves, down lines Ski-Doo DNA: Converging frontal lines
Suspension
The front and rear suspensions have been totally redesigned. The architectures are similar to the REV, but refined for better performance and lighter weight.
 | Up front, the REV-XP dual A-arm design is much lighter. The ski legs are forged aluminium, opposed to extruded on the REV, to accommodate the more complex geometry (resulting from the move from a rack-and-pinion style steering to a simpler triangular pitman arm system). The SC-5 is a more refined version of the SC-4, with improved weight transfer and better bump absorption. A new shock link and unique front torque arm make the centre shock less rising rate, enabling the suspension to use all the shock stroke for better efficiency. The new rear arm and spring location allow more rear axle travel without affecting ride height. The wheels have been placed in optimal locations for quieter operation and better hyfax wear. Through better design and optimising of materials, the rear suspension has dropped eight pounds (3.6 kg). The SC-5M mountain-specific suspension is a major upgrade over the SC. There is less weight transfer than the SC suspension, so the sled stays flatter when going uphill for better control, but still has the lift needed to run in powder. The centre shock is a falling-rate design, while the rear is slightly rising rate. Geometry is very similar to hillclimb race sleds. Because this is a mountain suspension, weight reduction was paramount – there are material-saving holes everywhere and lightweight wheels specific to this suspension. The rear idler wheels increase to 7.8 inches (200 mm) in size. Total weight reduction is nine pounds (4.1 kg) vs. the SC. |
All new REV-XP-based sleds will be shod with new REV-XP tracks – RipSaw REV-XP on trail sleds and Challenger Lite REV-XP on mountain sleds. Single-ply construction and a 2.86-inch (7.3 cm) pitch reduce weight by 4-6 pounds (1.8-2.7 kg) compared to the previous versions and run quieter, with improved acceleration and traction.
Engine System
Engines are mounted differently to the REV-XP chassis than the REV. Mass centralization and roll centre are improved, as the engine is mounted vertically (vs. six degrees forward) and 1.14- inches (29 mm) lower in the chassis. The engine is suspended in the chassis, rather than supported from the bottom, making the engine more stable, reducing belt flex. Minor modifications are made to the engines to accommodate this new mounting system.
Cast aluminum engine mounts save 1.5 pounds (0.68 kg). The pipes are lighter due to .04 inches (1 mm) vs. .047 inches (1.2 mm) walls.
Driveline
Key to the REV-XP concept was opening up the footwells and shin area to accommodate the additional legroom. This was made possible by moving the secondary clutch and jackshaft over the tunnel – Over the Tunnel Drive (OTD). This required an extensive redesign of the driveline. Engineers also took the opportunity to reduce the weight of every part, with a total driveline weight reduction of 8.9 pounds (4 kg) compared to the REV.
Primary TRA VII Secondary · New two-roller design on 5-axis machined cams · More efficient operation, better backshifting · 2 pounds (0.9 kg ) lighter than HPV Roller · Permanently fixed-on jackshaft for lighter weight. To remove secondary, simply remove the cap on the chaincase, loosen the chain, unbolt the shaft – no need to open the chaincase. Secondary cams can still be changed easily. · Cooling ribs on the outside of the sheaves were computer designed for optimum cooling and drag reduction, so no windage plates are required. Driveshaft · Hydroformed · 3.6 pounds (1.6 kg) lighter than REV. The result is a weight reduction of 41% (5.7 pounds REV-XP vs. 9.7 pounds REV/2.6 kg vs. 4.4 kg). · Eight-tooth internal/external drivers Brake · All-new design · Brembo‡ · Dual-piston · Mounted on driveshaft/tunnel · Caliper housing cooled via cut-out in tunnel · Composite master cylinder Chaincase · Magnesium for reduced weight · Stretched to 14.27 inches (32.6 cm) centerto-center for OTD · MaxLock riveted to frame · Part of sled’s structure · Speed sensor integrated into cover |  |
Gauges
The REV-XP gauge system is light years ahead of the previous iteration. There are actually two different analog/digital gauge clusters – a standard version and a premium Multi-function LCD version. Both feature an analog speedometer and analog tachometer.
Both gauge packages are completely electronic, including the fuel gauge.
Each cluster is easy to remove for adjusting the headlight and making repairs. For anti-theft purposes, a unique electronic code must match the code in the Engine Control Module to operate.
Standard Analog/Digital Gauge
