CP Piston & Ring Set for Mitsubishi 4B11 Evo X - Bore (90.5mm) - Size (+4.0mm) - CR (8.8) - Set of 4

This is a set of four forged pistons and rings from CP Pistons, specifically made for the Mitsubishi 4B11 engine found in the Evo X. These aren't your average replacement pistons; they're built for performance applications where the stock components might not hold up. The pistons are 90.5mm in bore size, which is a +4.0mm oversize from the factory specification, meaning they're intended for engines that have been bored out to accommodate them. The compression ratio is set at 8.8:1, a slight bump from stock that's designed to work well with performance tuning and modifications without being excessively high for pump gas.

CP Pistons are well-known in the performance engine building world for their robust construction. These pistons are forged from high-strength aluminum alloy, which gives them superior durability and resistance to detonation compared to cast pistons. This makes them a solid choice for builds that see track use, hard driving, or significant power increases from turbo upgrades or engine tuning. The included rings are also designed to work with these performance pistons, ensuring a good seal for optimal compression and oil control. Because these are an oversize piston, they are intended for an engine that has already been machined to the 90.5mm bore size. This is a critical step for rebuilding or modifying your 4B11 engine for increased reliability and power.

When rebuilding an engine with these pistons, it's important to follow the manufacturer's recommended clearances and installation procedures. Proper balancing of rotating assembly components is also recommended for smooth operation and longevity. This set is designed for the 4B11 engine and is a key component for anyone looking to build a stronger, more powerful engine for their Evo X.