Cosworth EJ25 (STI) short block has gone through countless hours of dyno evaluation to determine the best combination of parts to guarantee maximum reliable performance. Each EJ25 short block starts with a brand new Subaru case. The case is inspected and then the bores are honed to perfection to receive Cosworth Forged Pistons. We then balance the rotating assembly that includes a new 79mm Billet Crank and Cosworth Forged H-Beam Connecting Rods to within .5 gram. The select parts are professionally assembled by one of Cosworth’s skilled engine builders using our own coated, tri metal race spec bearings.

Options include: Billet 79mm crankshaft, Billet timing belt guide. For added performance, please see our Cosworth CNC ported Big Valve Cylinder Heads and high performance camshafts.

New Subaru EJ25 STI Engine Case

New 79mm Billet Crankshaft

Cosworth Forged Connecting Rods

Cosworth Forged Pistons

Cosworth High Performance Piston Rings

Cosworth Race Spec coated Tri- Metal Bearings

Balanced and Professionally assembled