1998 Subaru Legacy GT Wagon Project - BP5 Engine Swap

If you've been following our sister mag Import Tuner for the past year, you might be aware of Project Legacy. In previous issues, we addressed everything we could in the looks department of the '98 Subaru Legacy GT Wagon, but now it's time to give the car some serious go.

While we love the style of a '90s Subaru in the U.S., they were all too slow. Into the early 2000s, most Subies were powered by the gutless U.S.-spec 2.5-liter naturally aspirated motors or some other version of an N/A powerplant. These motors put out some dismal horsepower numbers from the factory; add to that common head gasket issues and you have a motor that's just begging to be pulled out.

Our Project Legacy is no different. The original motor had the head gasket let go almost immediately after we picked it up. After barely escaping an engine fire and hearing some serious rod knock, we knew it was time to give the swaggin' wagon a new heart. So we limped the Legacy over to JDM Engine Pro to see if we could get a proper motor and drivetrain sorted out.

Sure enough, JDM Engine Pro found us a perfect JDM 2.0-liter turbo motor from a '05 BP5 Legacy, along with a five-speed manual and the entire diff assembly with limited-slip. Score!

The beauty of this motor is that it comes turbocharged from the factory with a twin-scroll setup and features Subaru's Active Valve Control System (AVCS). Once JDM Engine Pro got the motor sorted out for us, we dropped the car off at one of SoCal's finest underground Subaru shops, Ubersport Performance. These guys are excellent at what they do, and all of their awesome work comes out of a tiny space. It reminded us of what many shops look like in Japan, so we were already stoked to be there.

Taking one final look at our original motor, we discovered something quite shocking.

It turns out that we drove our Legacy a little too hard with the blown head gasket—the motor got so hot it actually caught on fire! (See the white char marks on the headers?)

We also discovered that the thermostat literally melted out of its housing.

Once we were done looking over the damage, it was time for the fun part. The guys went to work at lightning speed and had the stock motor and tranny out in less than 90 minutes.

With the old engine gone, it was time to pop our JDM hotness in, but first, we had to make sure all this new power would travel to the ground properly. We switched out the old and rusted stock clutch components for some new goodies from Spec Clutch. Just look at the difference in flywheels! The JDM 2.0GT motor uses a dual mass flywheel setup that is said to be perfect for fuel economy and torque. While all those parts will work well in theory on a stock motor with no bolt-ons, we decided to trash that setup for a much lighter Spec flywheel. Plus, we have some go-fast goodies we plan on installing that will take care of the torque and power issues.

Before it was time to put the turbocharged 2.0-liter in our car, we test-fit some very rare pieces from CDF Racing to give our engine some bling and to help dial in the power. CDF sent us over some clear cam covers along with these beautiful billet aluminum adjustable cam gears. As much as we really wanted to put these on our car, they just didn't seem to fit right on our JDM motor; however, they fit a USDM STI motor perfectly.

With all the mechanics in place, it was time to pull the dash and climb the huge mountain of wiring. Since this isn't just a plug-and-play swap, the JDM wiring harness had to be merged with the UDSM harness so all of our sensors and gauges work. The easiest way to tackle this job is to pull the dash from the car and get access to all the wiring. Ubersport pulled the dash with a quickness and got the two harnesses lined up to merge. Since wiring is a pretty labor-intensive and detailed process, we'll continue the build next month. Stay tuned for more updates where we reinforce the chassis components and get some very special go-fast goodies fab'd up just for us to breathe some ponies into this JDM motor.

EJ History
by Aaron Bonk

Subaru's line of EJ engines runs about as deep as any Japanese automaker could hope for, including Nissan's SE, Toyota's A, or even Honda's B-series. First introduced in 1989, Subaru's flat-four Boxer layout poised itself as a worthy competitor against other then-relatively-new turbocharged makes, like Mitsubishi's 4G63, for example. Since '89, the EJ has adapted technologically, culminating into the Japanese-spec EJ20X (automatic) and EJ20Y (manual) pair introduced for the 2003 model year underneath the hoods of select fourth-generation Legacies. Indicative of their names, both feature two liters of cylinder space by means of an open-deck, aluminum block with partially forged internals and differ mostly by their factory-supplied, twin-scroll turbos. It's the engines' AVCS (Active Valve Control System) that you care about, though, which, unlike their predecessors, can be found on all four camshafts. Here, a solenoid triggered by the engine's ECU and a series of sensors adjust camshaft phasing for optimal power and emissions, depending on the circumstances. It's part of what allows a 2.0L four-cylinder engine to put down more than 280hp, idle like your mother's station wagon, and still pass a smog test. Changes varied throughout the engines' life span, which was mostly limited to turbo sizing. Early manual transmission-equipped models featured what was almost standard issue for many 1990s factory turbo rides, the TD04, and were later fitted with a better-flowing VF45. Swap the turbos on either of the engines, massage the fuel system and ECU and upward of 350whp is entirely possible without ever delving into the short-block, which we plan to do with Project Legacy.