Behind the Scenes Look at Polaris’ new ProStar 900 Twin Engine

Posted on January 30, 2011

By now, you’ve probably seen lot’s of pictures, a few videos and some first-hand reports on the new Polaris RZR XP. After experiencing it first-hand myself at the 2011 Polaris RZR XP Media Event, I can tell you that it lives up to the hype. The RZR XP is pretty much as Polaris states – “The ultimate combination of power, suspension and agility.“

The heart of the Polaris RZR XP features a brand new engine, designed in-house at Polaris called the ProStar 900 Twin. The ProStar was specifically designed for the RZR XP. It is not just another bored out ATV engine with a different cam profile and CVT adjustments. The ProStar 900 puts out an industry-leading 88 horsepower with an RPM limited to 8250. When you couple the 88 HP with the RZR XP’s 1190 pound dry weight, the result is a side x side that delivers 29% faster acceleration than the closest competitor.

Maximized Power
The Dual Overhead Cam (DOHC) valve train features high flow ports, fewer moving parts, and less total mass, maximizing engine performance and durability. Massive dual 46mm throttle bodies feed the 875cc ProStar which delivers a dynamic 100 HP per Liter compared to just 85 HP per liter for the closest side x side competitor.

High Performance Engineering
The 180 degree crankshaft configuration allows for an efficiently balanced and powerful side x side engine. The counter motion of the pistons reduces the amount of rotating mass inertia that is counteracted with the balance shaft. This results in a smooth and lightweight design. The naturally balanced design of the 180 degree crank provides smooth high-revving power.

Lightweight Powertrain
The new compact transmission was specifically built for the RANGER RZR XP to optimize power from the new ProStar 900 EFI engine. Its high torque transports extreme power to the wheels with less driveline noise. A helical cut final drive with optimized gear geometry maximizes efficiency for more power to the ground.

Built for Extreme Conditions
The integrated oil cooling and engine coolant system optimizes performance and durability when riding in hot weather conditions.

ProStar 900 Twin Specifications:

88 HP
Dual Overhead Cams
Four Valves per Cylinder
875cc Displacement
93mm Bore x 64.4mm Stroke
10.5:1 Compression Ratio
46mm Throttle Bodies
1.875″ exhaust header
37.7mm intake valves
32.4mm exhaust valves

More Polaris RZR XP Resources:

Manufacturer Info:

Website: Polaris Industries

Polaris Industries, Inc.
2100 Highway 55
Medina, MN 55340
(763) 417-8650

Polaris designs, engineers, manufactures and markets off-road vehicles (ORVs), including all-terrain vehicles (ATVs) and the Polaris RANGER®, snowmobiles and Victory Motorcycles® for recreational and utility use. Polaris is a recognized leader in the snowmobile industry, and one of the largest manufacturers of ORVs in the world. Victory Motorcycles, established in 1998 and representing the first all-new American-made motorcycle from a major company in nearly 60 years, are rapidly making impressive in-roads into the cruiser and touring motorcycle marketplace. Polaris also enhances the riding experience with a complete line of Pure Polaris® apparel, accessories and parts, available at Polaris dealerships. Polaris Industries Inc. trades on the New York Stock Exchange under the symbol “PII,” and the Company is included in the S&P Small-Cap 600 stock price index. Information about the complete line of Polaris products, apparel and vehicle accessories, is available from authorized Polaris dealers or anytime from the Polaris homepage at www.polarisindustries.com.