CP Pistons Aluminum Forged Piston Set 99.5mm 8.2:1 C/R | 04+ Subaru WRX STI EJ257 (SC7420)

The piston is the weak link in the stock STI block. By adding these forged pistons to your stock STI block you are able to get 500+ hp out of the motor. These pistons are Standard bore +.020 pistons are available as well.Features include:High Strength Aluminum forgingsSuper Lightweight designsFully CNC Machined and balanced to +/- 1 gramWrist pins included Accumulator groove included double pin oilers, force fed from oil ringpick lock grooves for easy lock removal

Features

• High Strength Aluminum forgings
• Super Lightweight designs
• Fully CNC Machined and balanced to +/- 1 gram
• Pin lock grooves for easy lock removal

Benefits

• Anti-Detonation Grooves protect the top ring by disrupting detonation waves. Limiting the piston/cylinder contact during high temperature and RPM.
• A V shaped Accumulator Groove machined in the 2nd ring land to collect excess blow-by between the top and second ring. This groove collects residual gasses during combustion and alleviates top ring flutter while increasing ring seal.
• A Constant Pressure Groove works as a channel on the lower part of the top land that equalizes pressure to the back of the top ring groove. When used in combination with lateral gas ports, the CP groove helps keep gas ports clear of carbon build up. In addition, the CP groove prevents the top land from smudging into the top ring if the land rubs the cylinder bore.
• Double Pin Oilers in conjunction with their dual fed reservoir add twice the amount of oil from the cylinder wall to the wrist pin.

Applications

• 2004+ Subaru Impreza STI

What’s in the box?

• CP Pistons Aluminum Forged Piston Set 99.5mm 8.2:1 C/R
• Includes piston rings, wrist pins, and circlips