After several years of testing and development, the Cosworth CS600 series High Performance Subaru EJ25 long block has arrived. The CS600 series is designed for extreme track day use and the demanding performance enthusiast. Each assembly is precision built by one of Cosworth’s skilled craftsmen using the finest components from our parts catalog to ensure maximum reliable power and performance. Starting with a new Subaru EJ257 semi closed deck block, we meticulously hone each bore to guarantee perfect piston to cylinder wall clearance. The block is then assembled with our Forged Pistons, motorsport grade Forged H Beam connecting rods along with our high performance rod and main bearings and a new STI Forged crankshaft. For maximum performance, an optional steel billet crank is available (CS600X). Once the cylinder block assembly is completed, we install a pair of our CNC machine port-bored Big Valve Cylinder heads with our proven “S2” camshafts complete with valve lash set to our specifications. The cylinder heads are secured with our high performance 11mm steel studs and sealed with multi layer steel head gaskets. Finally, we install one of our blue-printed, high pressure oil pumps for maximum lubrication. This proven engine combination has been used by top teams to win events in both North America and Europe and is available now for general sale.

Specification
New Subaru EJ25 STI Engine case
New Subaru EJ25 STI Billet Crankshaft
Optional Billet Cosworth Crankshaft (CS600X)
Cosworth Forged H-beam Connecting Rods
Cosworth Forged Pistons (CR 8.2:1) - also available in 9.2:1
Cosworth motorsport Tri-metal bearings
Balanced to within .5 gram
Complete blue-print assembly
Enlarged Intake and Exhaust ports
Large diameter stainless steel intake valves
Large diameter Inconel exhaust valves
Hi Rev, Dual valve springs
Titanium Retainers
Hardened Steel spring platforms
Multi angle valve job
Machined port finish
Knife edge port divider
Cosworth S2 High lift camshafts
Valve lash set
Cosworth high pressure oil pump
Cam covers
Cosworth serial number