Stage X 2.1 Forged Stroker Kit EJ20

This 2.1 litre forged stroker kit is built for power, torque, strength and reliability on the EJ20. An engine build or rebuild should only need doing once, so every component is chosen to be fit for purpose and to give a solid foundation for more power later.

Subaru EJ25 heat-treated crankshaft

The Subaru forged crankshaft is made by FHI Japan and is a strong, reliable and proven component. It is induction hardened for high wear resistance and is a good foundation for any performance engine.

Forged piston set

Forging is still the best way to make a piston, both for production and for strength. In a few areas a piston machined from solid is marginally better, but the strength benefits of a forging far outweigh them. A correctly forged piston has an excellent grain structure. A fully machined piston has no true grain flow, because the material is used as it is cut from the bar. Forging gives optimal molecular alignment in the material, and together with heat treatment this is what gives the piston its strength.

• Pistons are measured at a constant 20.5°C, as they can expand by as much as 10 microns in sunlight.
• The skirt profile is designed to work most efficiently at full operating temperature. It is elliptical in shape and barrelled along its length, and is machined with a repeatability of 5 microns.
• Each piston is weighed individually and batched to within 0.5 grams, so a set of four deviates by no more than 2.0 grams. Sets with only 0.1 gram deviation are not unusual.

H-section connecting rod set

The high-strength H-section rods are made from low-sulphur, vacuum de-gassed nickel chrome alloy steel, EN24 in V condition, with a shot-peened surface finish. Each rod is ultrasonically tested, crack detected and balanced to within a gram of the others.

ACL race bearings

ACL Race Series bearings are tri-metal engine bearings designed for higher rpm. They feature:

• High-strength overlay plate with reduced thickness for better fatigue properties
• Hardened steel backs on all rod bearings, to support the bearing lining better and help retain the bearing in the housing
• Increased crush for better bearing retention
• No flash plating on the back of the bearings, for better heat transfer and maximum grip between bearing and housing
• Increased eccentricity to compensate for bore distortion at high rpm and to help form hydrodynamic oil films
• 3/4 grooved main bearings, to optimise load-carrying surface area and oil flow to the rod bearings
• Tight, consistent wall tolerances to help maintain consistent clearances
• Enlarged ID chamfers on the bearing edges where required, to accommodate the large fillet radius on performance crankshafts

Engine block gasket kit and sealer

The kit includes the short block gaskets and the relevant sealer needed for installation. All gaskets are genuine Subaru, for quality, exact fitment and reliability.