Project Subaru EJ205 - Build Log

Subaru owners are an interesting bunch; they either love or hate their cars with a passion. I find myself indifferent and caught in the middle of the mix. On one end, I love my ’03 Subaru for a number of reasons, including its factory turbocharged, all-wheel-drive platform and readily available aftermarket parts. I even own an ’05 STI so it goes without saying: I’m a Subie loyalist through and true. So when I experienced engine problems for the first time with my ’03 WRX years back, I was a bit flustered. Why’s that you ask? I had grown up building Hondas and Acuras for most of my teenage years and being new to the Subaru world, didn’t know squat about the boxer engines as well as what to look for when problems arose. But, as time progressed, I became more familiar with the EJ205 engine’s internal workings as well as its pros and cons.

Follow along as we continue our EJ205 build from our Dec. ’11 issue. Here we tackle rebuilding the cylinder head and button up the bottom end using some key components to strengthen our engine so that it can handle more horsepower.

01 We recommend using the manufacturer’s torque specs to install components such as our connecting rods.

02 Always replace any used engine seals, including the crank seal, to prevent future leaks.

03 Vehicle manufacturers specify torque values for certain fasteners. This is to make sure that fasteners are not over or under tightened. The torque wrench is used to apply a specified amount of torq ue to a fastener. The torque angle gauge is used to make sure fasteners are equally tightened on a component such as the EJ205 engine block.

04 Our newly installed JE pistons

05 We installed ARP head studs, which offer more consistent clamping force for optimum sealing.

06 To promote an improved seal of the head gaskets, we used some copper coat gasket sealer on our MLS head gaskets.

07 The block is prepped and ready to install our cylinder heads.

08 The BC valvetrain component kit includes stainless steel valves, valvesprings, and titanium retainers.

09 Prior to installing our new camshafts, we inspected each of the buckets for indication of excessive wear.

10 Use a valve lash tool to measure the shimless buckets to acquire the correct valve clearance for the new camshafts.

11 BC Stage 2 camshafts were a perfect selection to our engine build. The camshaft’s short duration offered street driveability with only a slight lope at idle.

12 We are nearing final assembly of the engine as both cylinder heads were installed.

13 Oiling problems have always been a nemesis of the Subaru engine. To combat this problem we replaced the factory oil pump with a Cosworth high-volume/pressure pump. The Cosworth oil pump utilizes a completely new inner and outer 12mm rotor to increase volume by 20 percent.

14 Another reason not to use DEX-cool radiator coolant

15 Over torquing or using an air gun to install the factory cam gears can cause micro fractures within the phenolic plastic gears. The cracks will eventually fatigue the phenolic gears and shatter, sending your engine to hell as shown in the photo below.

16 Improper removal of the cam gears will cause a series of bent valves and additional out-of-pocket costs to rebuild your engine.

17 The AMS cam sprocket holder is a convenient tool for anyone planning to remove his or her cam gears. These tools feature a double-layered flange for maximum torque and durability, and are zinc plated for corrosion resistance and to hold the cam gear sprocket firmly in place while removing the center-retaining bolt.

18 AMS developed their cam sprocket holder tools to work with all ball locking half-inch square drive tools to provide a simple removal process without the headaches associated with homemade remedies.

19 BC cam gears were designed for the ’02-05 Impreza WRX EJ205 and ’04 Impreza STI EJ257 (none dual AVCS) engine. BC adjustable cam gears are CNC machined from 6061-T6 billet aluminum for durability. The BC adjustable cam gears are excellent upgrades from using the factory phenolic plastic cam gears. Its easy-to-read laser-etched face features micrometer-style markings for precise adjustment (up to 10 degrees in each direction) and quick tunability.

20 Installing the timing belt requires properly setting the timing.

21 The HKS timing belt was designed to suit the Subaru boxer engine, which has a very long belt and designed to be used with the stock EJ engine belt tensioner. The timing belt features high-saturation H-NBR (hydrogenated nitrile butadiene rubber) for added strength and will not stretch and warp as much as a stock belt, making sure your vehicle has the correct timing at all times.

22 In anticipation of increased power from our engine, we replaced the factory clutch with a Spec Stage 2+ unit along with a lightened flywheel. The Spec 2+ features a multi-friction disc in a full-faced configuration with carbon semimetallic on one side and Kevlar on the other. The more robust clutch setup offers 15 to 20 percent higher torque capacity but doesn’t have a heavy pedal feel often associated with aftermarket clutches, thus making it great for street, drag, and any future plans of road racing.