Legacy B4 RSK/GT BE5/BH5 (1998 – 2003)

Chassis Code Body Trim Engine Power* Torque* Rev Limit
BE5 Sedan GT EJ206 256 bhp @ 6000rpm 235 lb-ft @ 5000rpm 7000
BE5 Sedan RSK EJ208 276 bhp @ 6400rpm 253 lb-ft @ 5000rpm 7500
BH5 Wagon GT EJ206 256 bhp @ 6000rpm 235 lb-ft @ 5000rpm 7000
BH5 Wagon RSK EJ208 276 bhp @ 6400rpm 253 lb-ft @ 5000rpm 7500

*OEM published rating

Revision Production Dates Changes
A 06/1998 – 04/1999 Initial release, black ignition coils
B 05/1999 – 04/2000 No engine changes from Rev A
C 05/2000 – 04/2001 Updated grey ignition coils, larger turbos
D 05/2001 – 04/2003 New ECU system and sensors, larger top-feed injectors, larger primary turbo
Compression Turbo Peak Boost (bar)
Engine Ratio Primary Secondary Primary Secondary Max Airflow (g/s)
EJ206 Rev.A/B 8.5:1 VF25 VF27 0.70 0.85 220
EJ206 Rev.C 9.0:1 VF31 VF32 0.94 0.94 240
EJ206 Rev.D 9.0:1 VF33 VF32 0.94 0.87 250
EJ208 Rev.A/B 9.0:1 VF26 VF27 0.78 0.98 230
EJ208 Rev.C 9.0:1 VF31 VF32 0.94 1.00 240
EJ208 Rev.D 9.0:1 VF33 VF32 0.94 1.00 250

These cars come with either the EJ206 (GT) or EJ208 (RSK), a twin turbo 2.0L boxer engine. The ECU is a 32-bit model made by Unisia Jecs Corporation.

Improving reliability and common problems:

The Legacy Twin Turbo is popular due to its low price for a turbo vehicle but is notorious for poor engine reliability. In reality, the engine itself is no less reliable than a USDM Subaru turbo engine. However, due to lack of maintenance and the complexity of the twin turbo system, these engines often fail or are running poorly.

ECU tuning: The main source of problems for these cars is fuel octane. The JDM ECU is tuned for JDM fuel, which has a 98-100 RON octane rating vs Canadian 91/94 AKI (~95 – 98 RON). The lower octane range and engine condition usually result in detonation, which sounds like a crackle, or metallic rattle from the engine bay under medium to heavy throttle. projectLAMBDA has tunes for these ECUs to work properly on either 91 or 94 octane Canadian gas. The tune also increases the knock sensitivity of the ECU so that it can respond quickly to detonation before any damage occurs.

MAF sensor: A lot of these cars still have the original ~20 year old MAF sensor. They usually fail at higher airflow first by reading 10%+ too lean, which causes the ECU to run leaner fuel mixtures and higher spark timing without triggering the engine light. This leads to detonation and is the 2nd leading cause of damaged engine bearings on these cars. This can be checked by datalogging the ECU.

O2 sensor: Pre 2002 ECUs do not have any OBD2 capability cannot detect a failing O2 sensor unless it is unplugged. The ECU will overcompensate for a bad O2 sensor by adding up to 25% extra fuel, resulting in poor fuel economy. This can be checked easily by datalogging the ECU.

Twin turbo system: The twin turbo control system is overly complicated compared to other turbo vehicles. Leaks in the control hoses, missing restrictor pills, sticky/failed solenoids, and/or intake/boost leaks can all cause issues with the turbo system, such as low boost and slow boost response. Excessive detonation detected by the ECU will also cause it to turn off boost control.

Ignition system: Failed ignition coils or spark plugs. Rev C and later have upgraded coils which can be identified by their grey plastic housing. These coils can handle higher dwell times than the earlier black coils and can be retrofitted to Rev A/B along with increasing dwell time in the tune. Recommended spark plug is BKR7EIX at 0.8mm gap.


Hose 10 mod: The factory turbo control system has the wastegate solenoid bleed tied to the bypass valve pressure signal. This gives the turbo a smooth but laggy boost response. For Rev A to C this limits maximum boost to around 15 psi. The hose 10 mod removes this coupling and allows boost to exceed this 15 psi limit and allows faster turbo spool (recommended only with tuned ECU). For Rev D, this effect is less pronounced; hose 10 mod increases the wastegate solenoid’s effectiveness above 5000 rpm. Do not use this mod without a tune! The higher boost is will put engine load past the end of the stock fuel and spark timing maps.

Fuel pump: OEM 440cc injectors will max out the fuel pump above 85% duty cycle. Upgrading the fuel pump will allow you to run higher boost at high RPM without running out of fuel. The Rev D model does not need a fuel pump upgrade unless injectors are upgraded.

Air intake: Aftermarket cone filters that bolt directly onto the MAF are not recommended. This sucks hot air from the engine bay reducing the engine’s knock resistance and reduces the max airflow that the MAF can read. MAF sensors also don’t seem to last as long with the cone filter. The stock airbox with the fender well snorkel box removed is adequate for OEM turbos.

Catback exhaust: +5-10 whp, faster spool. Tuning may be required to prevent boost spikes/oscillation.

High flow downpipes: We haven’t done extensive testing but this is probably a worthwhile modification.

Aftermarket header: Both parallel and sequential headers are available. A parallel header can deliver similar performance to a OEM STI-sized single turbo setup.

Single turbo swap: Later spool, but smoother and increased torque/boost curve. Depending on turbo size, power can also be increased. Legacy ECU should be re-used and reflashed with a single turbo tune to avoid having to make changes to the wiring harness.

Engine swap:
Rev A, B, C: The 1998-2001 non-AVCS EJ205 and EJ207 engines bolt-in and don’t require wiring harness modification. For Legacy ECU, engine wiring harness and ignition coils should be re-used. Newer EJ engines can be swapped if crank/cam sprockets and some sensors are re-used. Working AVCS is not possible on the Rev A – C ECU.
Rev D: 2000+ AVCS EJ205/EJ207, USDM EJ205 engines share a compatible ECU system and can be installed with some minor wiring harness modification.