Speedwerx Stealth Cylinder Head // Polaris 850 Patriot / 850 Patriot Boost 

This new twist on our Stealth Cylinder Head design is the best head option on the market to improve the throttle response and acceleration of your machine. These heads are built from raw, unfinished head castings which offers several advantages over a full billet head or our traditional Stealth Head Mod with a billet dome. Starting with a raw casting means we aren't limited to recutting an already finished stock chamber- we can shape the combustion chamber exactly how we want it just like we would with a billet piece. The stock casting also enables us to retain all of the highly engineered cooling design advantages the OEM head design provides, and works with our chamber design that increases the compression ratio to maximize power and performance on pump gas with no ECU reflash needed. They are also lighter that any billet design- the exterior profiling machibe work we do shaves .4 lbs off the stock head which puts them at .8 to 1.5 lbs lighter than aftermarket billet heads. While we were at it, the head bolt bosses were machined so the bolts are now sealed with reusable o-rings to make for an easier and cleaner installation with no silicone or sealer needed. Best of all, you get all of this with the lowest cost of any aftermarket option. Sold outright- no core exchange needed.

• Big Power Gains- +3-8 hp 
• No ECU Reflash Needed
• Retains Superior OEM Cooling Design
• Lightweight- Save Up to 1.5 lbs 
• Uses O-Rings on Head Bolts
• 100% Made in the USA 

850 / 850 BOOST Models  ( stock compression ratio is 12.5:1 ) + 3 peak hp  and +4-8 hp in the mid range, high elevation set ups will see even bigger gains with added compression.  

Available Part Numbers - Compression Ratios - Recommended Elevation Usage with Non-Oxygenated 91+ Octane Premium Pump Gas:

• POL850CHK-13.1 - 13.1:1 - 0-3000’ 
• POL850CHK-13.7 - 13.7:1 - 3000-6000’ 
• POL850CHK-14.3 - 14.3:1 - 6000-9000'   
• POL850CHK-14.9 - 14.9:1 - 9000’+

If you wish to use pump gas at varying elevations, order for the lowest elevation you regularily ride at. Higher compression heads can be used at lower elevations with high octane race fuel or a race/pump blend, however we do not have specific fuel recommendations for these cases.

This new twist on our Stealth Cylinder Head design is the best head option on the market to improve the throttle response and acceleration of your machine. These heads are built from unfinished head castings which offers several advantages over a full billet head or our traditional Stealth Head with a billet dome.