Subaru EJ20
Like the 4G63, the EJ20 has been around for a long time, and was offered in various configurations. Unfortunately, the US received a choked-up version. Power-wise, turbo response was slow and lacked good low- to mid-range torque. Most of this was rectified with the later 2.5-liter motors, but the 2.0-liter is still responsive to upgrades and light tuning, which greatly helps drivability and performance. - Jon Kuroyama, HKS
Stock [178 whp]
Stage 1 [210 WHP]
Exhaust [HKS Hi-Power]
Downpipe [HKS]
Up-pipe [HKS]
Intake [HKS Super Hybrid Filter]
Stage 2 [240-280 WHP]
Boost Control [HKS EVC]
Intake [HKS Super Mega Flow Kit]
Intercooler [HKS FMIC Kit]
Ignition [HKS Twin Power DLI-II]
Tuning [HKS F-Con iS]
Stage 3 [320-380 WHP]
Turbo [HKS GT Sport Turbo Upgrade]
Turbo Exhaust Manifold [HKS]
Injectors [HKS]
Tuning [HKS F-Con VPro]
Source:
HKS
hksusa.com
310.491.3300
Subaru EJ25
The challenge of tuning the 2008-up EJ257 STI engine lies not with the motor itself, but with the engine management system that controls timing, fueling and air flow. The OEM ECU is often times too smart for its own good, especially when trying to improve the overall power of the vehicle. Achieving reliability is the hardest part of tuning the engine via the OEM ECU. With that in mind, a tuner like us must adjust nearly 50 tables to tailor make a unique and reliable driving experience for each individual customer.
A tuner must know that certain point where the limit is reached. Once at that limit, just pulling back the tune is not sufficient enough. We must understand the small things like the differences between different brands of fuel, to knowing how the layers of compensations and dynamic corrections relate and work synergistically to create a solid and reliable tune. - Bill Knose, Crawford Performance
Stock [240 WHP]
Stage 1 [265 WHP]
Tuning [Cobb AccessPORT]
Crawford Performance Stage 1 Map
Stage 2 [288 WHP]
Engine [Crawford Performance Air/Oil Separator]
Downpipe [Crawford Performance 3-inch divorced-wastegate style]
Tuning [Cobb AccessPORT]
Crawford Performance Stage 2 boost-up Map
Stage 3 [315 WHP]
Crawford Performance Front
Mount Intercooler
Tuning [Cobb AccessPORT]
Crawford Performance Stage 1 Map
Source
Crawford Performance
crawfordperformance.com
760.631.2927
The Subaru EJ25 motor can be a very potent platform when handled with thoughtful attention. The opposed layout leads to a fairly vibration-free engine, the long connecting rods and large diameter pistons allow for copious amounts of torque, which is great for bringing smiles out. The main weakness is the intake manifold, which is only designed for low-end torque and as such does not lend itself to revving past 7,500 rpm. The oil pump becomes a concern at around 8,200rpm, which is generally well past peak power, so we have room to move with that. The pistons are definitely more detonation tolerant than the WRX pistons and higher compression (8.2:1 vs 8:1) which helps off-boost power. It is easy to work on for the most part and requires very few specialty tools in order to get it at what you want. - English Racing
Stock [230 - 240 WHP]
Stage 1 [310-320 WHP]
Exhaust turbo-back [APS] [HKS] [A'PEXi]
Intake [K&N Open element]
Fuel System [Walbro 255 lph]
Boost [factory setting]
Stage 2 [370-375 WHP] adds
Turbo [FP Green bolt-on turbo upgrade]
Fuel System [880cc injectors]
Intercooler [FMIC]
Boost [21 psi]
Stage 3 [440whp]
Turbo [Precision 6057]
Pistons [Manley] [Wiseco]
Rods [Eagle]
Camshafts (4) [GSC Motorsports S1 S2]
Intake manifold [Magnus Motorsports sheetmetal large plenum]
Ferrea valvespring kit
Boost [24 psi]
Stage 3 [for 500+ lbs-ft of torque]
Block [Magnus Motorsports sleeved block]
Internals [Magnus Motorsports 2.8-liter stroker kit]
Source
English Racing
englishracing.net
360.210.7484