Subaru STi 630+ Horsepower Street Car

THRICE BUILT BOXER

630+ Horsepower Street-driven Subaru STiAfter running the EJ257 in stock form with bolt-on upgrades for a few years, the engine bearings failed, forcing a rebuild. Working with his friend Brett Carter, a tech at the AutoNation Subaru Dealer in Golden, Colorado, the EJ257 was refreshed with new bearings and dropped back into the engine bay. This engine benefitted from a new Exedy twin-plate clutch, Forsa intake manifold and a new radiator. After a brief time on the road, one of the pistons cracked, sidelining the STi once again.

[pullquote]HAIL STORM CAUSED SEVERE BODY DAMAGE TO THE STI[/pullquote]This time, a local shop installed sleeves and low-compression pistons. During the down time, he upgraded the brakes with a Brembo Gran Turismo kit that peeked through the spokes of bronze colored Volk Racing CE28N wheels mounted with sticky Toyo R888 rubber. Shortly after, a hail storm cause severe body damage to the STi, prompting English to enhance the aesthetics of the car. An AMS carbon-fiber roof replaced the stock unit, while a complete Charge Speed aero kit enhanced the GDB bodylines.

630+ Horsepower Street-driven Subaru STiBut misfortune found him shortly after, as one of the cylinder sleeves sank, forcing English to go back to the garage once more. On good advice by Carter, English pulled the stops and went to Abbott Speed & Fabrication (ASF) to have a high-compression race engine constructed. Since he lived a mile above sea level with reduced air density, running a high-compression engine with higher boost made sense. ASF dropped in a set of Darton ductile iron sleeves before boring the block to the factory 99.5mm specification. After honing, 10.0:1 compression Ross Racing Pistons filled the bores. Carrillo Pro H-beam connecting rods link the pistons to the now heat-treated factory crankshaft. The cylinder heads received a port and polish service, along with a radiused valve job. Once the heads capped each end of the block and the assembly was secured together with ARP fasteners, GSC Power Division S4 camshafts were installed in the heads to actuate the valvetrain. To protect the engine from catastrophic oil starvation, English incorporated a Peterson Fluid Systems three-stage dry sump system.