Subaru EJ255 / EJ257 WRX-STi 8.5:1 ZRP 1400HD Forged Pistons by Wiseco

ZRP, in collaboration with Wiseco, created a unique new series of pistons made in the USA from 2618 alloy and sharing many advanced features with the Wiseco HD1400 series for extreme high-HP setups.

The pistons include upgraded pins with a 5.34mm wall thickness and Armor Plating piston coating to reduce the adverse effects of high heat in turbo and nitrous/methanol setups. Each ZRP piston in this application includes an ArmorGlide anti-friction skirt coating to minimize scuffing during break-in and reduce friction on the cylinder wall. Our pistons are made from dedicated in-house forgings, providing lightweight pistons with superior strength and an optimal design. The valve pockets are also bigger and deeper than OEM pockets to accommodate high-lift camshafts. Moreover, the pistons have offset pins and gas-pressure and anti-detonation grooves to prolong ring life!

What is the Armor Plating piston coating?

The Armor Plating coating gives the pistons a bronze tint on the crown and wrist-pin bore. This abrasion-resistant plating increases the aluminum's hardness, enhances the durability of the ring grooves, prevents micro-welding of the piston rings, reduces carbon buildup, and combats corrosion from detonation. The Armor Plating coating also reduces the piston crown temperature by 20°C on average!

What is the ArmorGlide anti-friction skirt coating?

ArmorGlide skirt coating is made from a moly solid-film lubricant and is permanently bonded to the pistons. One of its main features is its ability to resist seizure and reduce friction, ensuring quiet operation. It also reduces piston rock and noise while increasing power.