Polaris 2019 850 Pro RMK

850 Patriot Engine

One of the biggest things—literally and figuratively—to come out of Polaris for 2019. But you better act now if you want one because the 850-equipped snowmobiles are available during Polaris SnowCheck program. We learned from Polaris engineer Jim Barczak that when the 800 H.O. Polaris engine was revealed in West Yellowstone, MT, the company was already working on the architecture of the 850. Highlights of the new engine include:

• Most powerful Polaris snowmobile engine ever
• Incredible 4-year warranty
• New piston: +8mm compression height; improves heat transfer
• PVD-coated steel single ring design
• +3mm thicker dome
• Higher capacity wrist pin
• +23 percent more contact area with cylinder bore to improve heat transfer

• New lightweight crankshaft; symmetrical press fit webs for improved straightness; separate crankpins feature high-grade steel; higher capacity bearing and pin design; larger clutch taper design for durability and serviceability
• New cylinder/cylinder head; advanced cooling system with consistent flow velocities; leveraged computation fluid dynamics; 6-bolt cylinder structure optimized with Finite Element Analysis (FEA); one-piece head design is lighter than a two-piece design; patent-pending combustion chamber design
• New water bottle with integrated thermostat; patent-pending coolant bottle design; simplified, integrated design to minimize vibration and maximize thermostat life; self bleeding cooling system; 100 degree T-stat; integrated bypass for fast warm up
• New throttle body/throttle position sensor (TPS); lightweight throttle body features a lightweight, simple and durable design; features a contact-less TPS for reliable, consistent performance; permanent set—no adjustment required

• New 3-stage E-VES-II exhaust system; simplified coplanar valve with less parts, lighter weight; EV base is lightweight, magnesium die cast; improved fit and sealing to the piston and exhaust ports to control exhaust flow and optimize performance; optimized water jacket and valve cooling
• “We’ve taken the water jacket and optimized it to have a high velocity system to remove as much heat as possible for the cylinders and head.” Jim Barczak
• Flowing slightly more coolant through the cylinders and head
• Crank is 3 lbs. heavier; added weight is in the center of the cranktrain
• All bearings are bigger
• Engine is equal to or slightly more narrow than the Liberty 800