ProX Pistons Provide Affordable Performance for Polaris RZR 800 Engines

July 8, 2020 / by Paul Olesen

ProX is proudly bringing budget-friendly and reliable performance to RZR 800 engines in need of a rebuild. Manufactured by OEM suppliers with additional features added, these pistons help keep the fun going without breaking the bank.

In recent years, the UTV market has exploded in popularity among enthusiasts. One of the flagship machines that led the growing interest in UTVs was the Polaris Ranger RZR 800. The RZR 800 is a versatile, high-performance UTV that has been on the market for over a decade. Early model RZR 800 engines can be rebuilt to regain lost performance due to years of wear and tear.

The ProX team has been hard at work developing replacement pistons for the Polaris RZR 800 UTV. ProX's new pistons are packed full of performance-enhancing features and are now available through ProX’s distributors worldwide. The energy and development that has gone into these pistons is showcased in the key features that make these pistons stand out.

ProX's new line of pistons for Polaris 800 engines have enhanced performance features over OEM. Read on for all the details.

What makes and model years are the new RZR 800 pistons available for?

The new RZR 800 pistons are available for the following makes and models:

Part Number






RZR S 800

2009 - 2014



RZR 4 800

2009 - 2014




2009 - 2014



Sportsman 800 HO EFI

2008 - 2009

Performance Enhancing Design Features

The ProX team exceeded the original equipment manufacturer (OEM) specifications in several ways. ProX selected an AC8A cast alloy, which is equivalent to the OEM alloy utilized. The AC8A alloy was retained because it has superior mechanical properties. One of the benefits of this alloy is that it offers low thermal expansion, which creates a stable piston structure. A stable piston structure is key to ensuring excellent piston durability and optimal performance throughout the life of the piston.

These ProX RZR 800 pistons are cast using an AC8A alloy, which is also what the OEM uses, for less thermal expansion and a more stable piston structure.

Tight-tolerance CNC machines are utilized to fully machine the piston crown. ProX chose to fully machine the crown to improve airflow in the combustion chamber and create a uniform surface that could be hard-coat anodized. Improved airflow ultimately results in increased combustion efficiency and more power.

A fully-machined piston crown allows for precision execution of improved airflow crown design and achieves a uniform surface that can be hard-coat anodized.

The top compression ring land features a hard-anodized coating, which significantly improves durability compared to non-coated ring lands, and also helps improve heat resistance and reduces the possibility of micro-welding of the ring groove to the piston ring. Piston durability is further improved by incorporating an anodized piston crown, which helps improve heat resistance and reduces carbon build-up.

Hard-coat anodizing the top compression ring land greatly reduces the chances of ring microwelding while simultaneously increasing durability.

The MOS2 piston skirt coating is an essential part of ProX's piston design, with multiple significant benefits. The MOS2 coating is an abradable coating that allows the piston to conform to the cylinder bore throughout break-in. This coating allows a tighter running fit between the piston and cylinder. The coating itself features anti-friction properties, which reduce internal friction within the engine leading to increased power and reduced wear when compared to uncoated pistons.

The MOS2 skirt coating reduces friction during operation and allows the piston to better conform to the cylinder bore during break-in.

Piston Sizes

The RZR 800 pistons are available in three different sizes for stock cylinders that are within spec as well as those that have worn slightly larger. The three sizes ProX offers are listed below:

  • A = Standard Size (79.95mm)
  • B = Oversize (79.96mm)
  • C = Oversize (79.97mm)

In the U.S? You can find ProX RZR 800 pistons here!

Bore size showing a little wear? Optional oversizing allows you to retain proper piston to wall clearance in cylinders that have started to wear larger over time.

A Complete Package

When you purchase new pistons from ProX, you will receive everything you need to complete your piston assembly. Items included with ProX piston kits are:

  • Piston - ProX high-performance piston featuring all benefits mentioned above.
  • Ring(s) - ProX works with leading piston ring manufacturers to produce rings that meet exacting specifications. The rings included with your piston kit are developed to meet or exceed the OEM design.
  • Wrist pin - ProX utilizes precision grinders in combination with meticulous attention to detail throughout the heat treatment process. By focusing on these two processes, it's possible to produce wrist pins that can withstand the extreme conditions found within high-performance engines.
  • Wire locks - High-quality spring steel is utilized by ProX in their wire lock designs to ensure wrist pin retention throughout the life of your engine.
Each ProX Polaris 800 piston kit includes the piston, rings, wrist pin, and wire locks. All these additional components are manufactured by leading OEM suppliers, just like the pistons.

Need some tips on installing wire locks? Check out our guide here.

The new ProX RZR 800 pistons aim to provide an improvement in performance for tired RZR engines at a budget friendly price and are now available throughout ProX's distribution network. These new pistons meet or exceed OEM specs, feature numerous benefits ranging from improved fully machined crowns to anti-friction skirt coatings, and are offered at an affordable price. For your convenience, ProX piston kits feature everything you need to replace your pistons in your engine.

ProX Polaris 800 pistons aim to provide above OEM performance at a budget-friendly price. Find ProX pistons and other components for your machine here.

Topics: NEWS, NEW PRODUCTS, featured, Powersports, Tech, UTV

Related posts