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Project Subaru EJ205 - Build Log

Scott Tsuneishi
Feb 21, 2012

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.

Impp 1202 01 o+subaru ej205+parts Photo 1/23   |   Project Subaru EJ205 - Build Log

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.

Impp 1202 02 o+subaru ej205+torque specs Photo 2/23   |   Project Subaru EJ205 - Build Log

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

Impp 1202 03 o+subaru ej205+engine seats Photo 3/23   |   Project Subaru EJ205 - Build Log

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.

Impp 1202 05 o+subaru ej205+angle guage Photo 4/23   |   Project Subaru EJ205 - Build Log

04 Our newly installed JE pistons

Impp 1202 04 o+subaru ej205+je pistons Photo 5/23   |   Project Subaru EJ205 - Build Log

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

Impp 1202 06 o+subaru ej205+arp head studs Photo 6/23   |   Project Subaru EJ205 - Build Log

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

Impp 1202 07 o+subaru ej205+copper coat sealer Photo 7/23   |   Project Subaru EJ205 - Build Log

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

Impp 1202 10 o+subaru ej205+cylinder heads Photo 8/23   |   Project Subaru EJ205 - Build Log

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

Impp 1202 12 o+subaru ej205+steel valves Photo 9/23   |   Project Subaru EJ205 - Build Log

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

Impp 1202 14 o+subaru ej205+wear Photo 10/23   |   Project Subaru EJ205 - Build Log

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

Impp 1202 08 o+subaru ej205+valve lash Photo 11/23   |   Project Subaru EJ205 - Build Log

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.

Impp 1202 11 o+subaru ej205+bc stage 2 camshafts Photo 12/23   |   Project Subaru EJ205 - Build Log

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

Impp 1202 13 o+subaru ej205+cylinder heads Photo 13/23   |   Project Subaru EJ205 - Build Log

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.

Impp 1202 15 o+subaru ej205+cosworth pump Photo 14/23   |   Project Subaru EJ205 - Build Log

14 Another reason not to use DEX-cool radiator coolant

Impp 1202 09 o+subaru ej205+dex cool coolant Photo 15/23   |   Project Subaru EJ205 - Build Log

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.

Impp 1202 12 o+subaru ej205+shattered gear damage Photo 16/23   |   Project Subaru EJ205 - Build Log

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

Impp 1202 16 o+subaru ej205+valves Photo 17/23   |   Project Subaru EJ205 - Build Log

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.

Impp 1202 17 o+subaru ej205+ams cam sprockets Photo 18/23   |   Project Subaru EJ205 - Build Log

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.

Impp 1202 18 o+subaru ej205+gear Photo 19/23   |   Project Subaru EJ205 - Build Log

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.

IMPP_2011_12_BLOG_020 Photo 20/23   |   Project Subaru EJ205 - Build Log

20 Installing the timing belt requires properly setting the timing.

Impp 1202 19 o+subaru ej205+bm cam Photo 21/23   |   Project Subaru EJ205 - Build Log

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.

Impp 1202 20 o+subaru ej205+hks timing belt Photo 22/23   |   Project Subaru EJ205 - Build Log

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.

Impp 1202 21 o+subaru ej205+clutch Photo 23/23   |   Project Subaru EJ205 - Build Log


Calico Coatings
Denver, NC 28037
SPEC Clutch
Bessemer, AL 35022
Mississauga, ON, CA
Torrance, CA 90505
Torrance, CA
JE Pistons
Huntington Beach, CA 92649
Revco Precision Balancing
Lakewood, CA 90805
BC-Brian Crower Inc.
El Cajon, CA 92020
Engine Supply
By Scott Tsuneishi
247 Articles



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