When last we left our Project EJ25 build (May '14 issue), we assembled our bottom end using some key components, including Carillo Pro H-Beam connecting rods, JE Pistons, and a Cosworth high pressure/volume oil pump along with a pair of their head gaskets. Prior to mating the Port Flow-prepped cylinder heads, the entire rotating assembly was sent to Revco Precision located in Long Beach, CA, for a full balance and blueprint process. WPC Treatment also played an integral role in surface treating our crankshaft, King Engine bearings, pistons, and rods to create a harder, more durable surface with the added benefit of reducing surface friction.
For our third and final installment, we pull the wraps off the stuff you've been most waiting for: the turbo kit system and reverse manifold setup. If you recall, a deadly combination of over boosting due to a dislodged wastegate line at the track caused a lean air/fuel condition that melted our Cosworth piston, which caused a nightmare of chain reactions that ended with a dramatic engine fire. We were able to salvage the cylinder heads, but the block was decidedly thrown in the garbage and replaced with brand-new case halves we purchased from South Coast Subaru located in Costa Mesa, CA.
CDF Racing Adjustable Cam PulleysThe factory cam gears are designed using phenolic plastic and have been known to crack or break upon installation or removal. CDF Racing adjustable cam pulleys are a direct copy of the stock pulleys and have been used by professional race teams across the world including Vermont Sports Car Rally Team. These hard-anodized cam gears allow you to dial in your vehicle's aftermarket camshafts for maximum power by allowing your camshafts to open the valves to their limits. The CDF pieces are designed using stainless steel centers with Heli-Coil stainless threaded inserts and 12.9-grade bolts for superior strength and reliability. We used an AMS Performance's Subaru cam gear tool to remove and install all four cam gears.
KS Tech Intake/ Throttle Body SpacerWhen it comes to reversing your intake manifold, there's no easier way than using a set of intake manifold spacers. The KS Tech 9.5mm Phenolic spacers provide necessary alternator to throttle body clearance for any reverse intake manifold modification as well as insulating engine heat away from the manifold.
The KS Tech 1/2-inch throttle body spacer enabled us to mount our drive-by-wire throttle body to the manifold without having to rotate the piece to clear the DBW motor assembly. We should also note that KS Tech offers OEM quality intake and throttle body gaskets both in OEM size and enlarged bore diameters.
T1 Race Development Fuel SystemIt's no secret that the '04-06 Subaru STI side-feed injector upgrades are limited in upgrade sizing (850cc unmodified) in comparison to top-feed units. When upgrading our fuel system, we revealed that not only was injector size an issue, but upgrading to a top-feed injector required changing our TGV's (tumble generator valve) setup as well.
Killing two birds with one stone, we contacted T1 Race Development to purchase their T1 Side Feed Conversion Kit with optional fuel feed lines for our STI. The T1 fuel system was designed to retain the factory side-feed TGV's but replace the fuel rails with a top-feed fuel rail setup and spacers that allow the use of any Injector Dynamics high-impedance injector, ranging from ID725 to ID2000.
The CNC-milled 6061 aluminum top-feed injector rails are fed by lightweight black nylon performance hoses to a set of ID1000 injectors.
BorgWarner 7163 EFR TurbochargerBorgWarner's 7163 EFR (Engineered For Racing) Series turbocharger came highly recommended by Geoff Racier of Full-Race and with good reason. There's an abundance of turbochargers available on the market today, ranging from small to big. When opting on purchasing this kit, our intentions were not looking for pure top end, but a good combination of response, spool, and flow enough cfm to outflow any factory turbo when attacking any future road courses. The 7163 turbo uses a forged-milled 71mm od compressor wheel with a 57mm inducer to support an impressive 60 lb/min max flow rate and a low inertia 63mm Gamma Ti turbine wheel. The BW 7163 uses a B1 frame turbo, the smallest-sized EFR compressor-housing BW offers, which allows our STI to maintain the factory location turbo configuration without having to switch to a rotated setup. Initial testing by Full-Race using their bolt-on kit with the 7163 delivered a quick spool that was on par with the factory turbo and superior response till redline that was sufficient for the 400-550hp range.
Highlights of the turbo include Gamma Ti turbine wheels, dual-row ceramic ball bearings and cast stainless steel turbine housings, not to mention the boost control solenoid valve is also integrated to the compressor housing. An optional speed sensor kit is also available if you plan to push your turbo to the limit. We had our exhaust housing treated with a high-temp ceramic coating that's able to withstand over 2,000 degrees F.