Rotax 850 E-Tec Features
- The 850 is the second generation E-Tec (after the original 600) built at the Rotax factory.
- The 850 is 1 lb. lighter than the 800R and features booster injectors, which were added to the intake. The 850 features electronic direct injection, which is very precise in delivering the right mixture to the cylinder.
- The throttle bodies are 35 percent closer to the cylinders when compared to the 800R and are 10 percent lighter even with the added booster injectors. The Rotax-exclusive eRAVE exhaust valves have three positions that open and close three times faster than the 800R E-Tec.
- The ECM on the Rotax 850 manages the engine electronics at 32 million cycles per second, which is two times faster than the 800R E-Tec.
- Rotax used a new design (inspired by diesel technology) in the piston ring carrier to help ensure the engine will be as durable as possible. The 850 has forged aluminum pistons and cast iron insert holding ring.
- The Rotax-designed direct oil crank bearings puts the oil directly onto/through the bearings, meaning the oil is going only where and when it’s needed.
- The 850 uses a two-piece forged crankshaft.
- The engine is narrower so that it can fit in the Rev Gen4 platform. The 850 is 1.6 inches narrower on the magneto side and has been positioned 2.2 inches more to the center of the sled for better maneuverability, among other benefits. The new magneto is not only lighter but incorporates a ring gear for the starter.
- A Rotax exclusive on its engines is plasma coating the cylinders, which replaces nikasil. This reduces friction, partly because the coating is slightly porous and holds oil in its crevasses. There are 65 process steps for each part being plasma coated. This includes flow speeds, voltage, powder feed rate, time the cylinder block is in process, rpm of the plasma torch, Argonne gas concentration and the cooling temp of the water for the torch, just to name a few. It takes four minutes per block to plasma coat. Five layers of plasma coating are applied on four-stroke cylinders and six layers on two-stroke cylinders.
- Rotax is the only company in the world that offers plasma coating on two-stroke cylinders. Also, Rotax developed the process of plasma coating for two-stroke cylinders.
- Ski-Doo uses a three-point mounting system for the Rotax 850, partly to reduce weight but also to keep engine vibration to a minimum.