Crawford Performance has been a big name in the sandrail world for years (many of these off-road machines are powered by Subaru engines) and has built itself a name in that market. This extensive experience with the Subaru engines made the jump to the import scene almost a given, and as they say at Crawford, "The only question is: is street import racing ready for the power?"
Applying the knowledge they gleamed from tuning the Subaru-powered dune buggies, they started the re-build of the STi by turning to its horizontally opposed 4-clyinder engine. Laying the foundation for the kind of power they wanted meant the stock block needed to be fitted with a bulletproof bottom end before anything else.
The EJ25 received Crawford Performance's S5 shortblock treatment, which includes a billet stroker crankshaft, a set of Crawford billet 4340 rods and forged CP 8.1:1 compression pistons. Between the larger crank and pistons, the engine now rocks a displacement of 2.6-liters, as opposed to the stock 2.5 liters. Other mods to the shortblock include ARP fasteners, while the oiling system remains stock sans the install of an oil cooler. Crawford handled the machine work and assembly on-site.
With the shortblock in order, Crawford bolted up a set of cylinder heads and called it a longblock. Like many other parts on the car, the heads are 100 percent stock, sporting the OEM valves, cams, springs, retainers, etc. In essence, the engine build included a 100cc increase in displacement and some new internals-but the real power adder was the turbo kit.
Bolted to the 2.6-liter mill is a Crawford Performance CP-35R turbo kit. According to Crawford, the CP-35R kit was designed with one main goal-to make a lot of reliable power. The CP-35R kit comes with a genuine Garrett GT35R turbo, a Tial 44mm wastegate, Crawford up/down pipes, a cold air intake with a cone filter and miscellaneous fittings. A Crawford Performance 3-inch straight pipe serves as the exhaust and evacuates the spent gasses with ease. The intake and exhaust manifolds are the stock units.
The OEM top-mount intercooler, while adequate for the stock turbo at stock boost levels, just wasn't up to snuff for the bigger turbo. To address this, Crawford slapped on an APS intercooler to the front of the Subi. The 28x9.5x4.5-inch heat exchanger provides plently of intake charge cooling capacity.
When it comes to making power, building the engine is just the first step. Good tuning is just as important-if not more. Crawford upgraded the injectors, fuel pump and engine management when they installed their GT35 turbo kit-a necessity. A Walbro 255lph pump delivers the fuel to JEC 720 cc/min injectors, which are in turn fired by a stock ECU with an I-Speed re-flash with optimized fuel and spark settings. The stock ignition was retained. All said, the bigger turbo and tuning netted the Subi some substantial power increases: 450-wheel hp and 450 lb-ft of torque. A nice number for a street/track STi.
By Ryan McKay
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