Table of contents
Subaru EJ25 engine
The largest member of the EJ family was released in 1995 and carried the designation EJ25, and this engine is widely used in all major car models. The EJ25 Subaru engine used the same aluminum cylinder block with cast iron liners dry, which is applied in EJ20, but the diameter of the cylinder was raised from 92 mm to 99.5 mm, height remains the same (201 mm). The crankshaft was installed with 79 mm piston stroke, instead of 75 mm per 2 liter counterparts. The length of the rods remained the same 130.5 mm and the piston compression height was reduced to 30.7 mm (32.7 mm was). All this has made it possible to obtain a working volume of 2.5 liters.
In the first variation EJ25D used twin-shaft cylinder head (DOHC) with 4 valves per cylinder. Drive timing belt and timing belt replacement is necessary every 100 thousand. Km. EJ25D Power is 155 hp at 5600 rev / min, 1997 changed the pistons and power climbed to 10 hp
This motor was raised until 1998, and later was replaced by a more modern engine EJ251. It relates to a power plant and Phase II equipped with a new cylinder head, one on each camshaft (SOHC), as well as new molybdenum-coated pistons, the compression ratio increased to 10.1. Produced and EJ252 engines meet the high environmental standards of the State of California and the different intake throttle valve position of idling and DBP.
In 1999 it appeared the form of the 25th – EJ253 engine, with DMRV instead of DBP, in the intake manifold of the engine there appeared flap Tumble Generator Valves, which helps to improve environmental performance. Since 2006, I began to be used i-AVLS system changes the lift height of the intake valves. In 2009, the number of motor finalized, after which he received the lightweight pistons, modified intake ports, a plastic intake manifold, the other spark plugs, refined system i-AVLS, facilitated by the exhaust system.
In 1998 it was released with twin-shaft EJ254 with DOHC cylinder head, which is the heir EJ25D and related to Phase II. The Motor is using AVCS system on the intake camshafts.
EJ255 engine has become established on the Forester, Impreza WRX and Legacy from 2004-2005 and was a turbocharged engine with a semi-closed unit, DOHC cylinder heads and variable valve timing on the intake camshafts AVCS. Compression ratio in the EJ255 reduced to 8.4 units used turbine TD04L, boost pressure is 0.8 bar. This makes it possible to remove 210 hp at 5600 rev / min. In another version of the engine, boost was increased to 0.93 bar, set a larger intercooler and removed 230 hp at 5600 rev / min. Also on the EJ255, Japanese Forester STI, the turbine was VF41. On WRX III the turbine was VF52, inflating 0.92 bar. On the Legacy GT VF46 turbines (pressure of 0.95 bar) were set up in 2009, which provided 250 hp at 6000 rev / min. After 2009 on the Legacy GT turbine installed VF45 (pressure 0.87 bar), it has added another 15 hp
On WRX STI versions used EJ257 engine with a semi-closed cylinder block, other pistons compression ratio under 8.0, modified cylinder head with the other combustion chambers, with AVCS system. This engine is a turbine IHI VF48 (boost pressure of 1 bar), it is sufficient to remove the power of 280 hp at 5600 rev / min. The EJ257 for the WRX STI III with compression ratio of 8.2, was added AVCS system on the intake and exhaust camshafts, power increased to 300 hp at 6000 rev / min, 407 Nm of torque at 4000 rev / min. In the US STI turbine used IHI VF39, the boost pressure of 1 bar.
In addition to the EJ20 and EJ25, a series of EJ included EJ15, EJ16, EJ18 and EJ22.
Since 2011, the atmospheric 2.5-liter EJ were replaced by FB25, and the turbo FA20.
Subaru WRX STI 2003 engine sound
EJ25 engine specs
This engine is also installed in
- Subaru Impreza (WRX/STI)
- Subaru Forester
- Subaru Legacy/Outback
- Subaru Baja
- SAAB 9-2X
EJ25 2.5l engine Problems and malfunctions
EJ25 2.5 liter engine has the same problems as 2.0 liter. About them you can read here
Subaru EJ25 engine tuning
Exactly as with the 2-liter EJ20, EJ25 and many other atmo engines there is no sense to tune them. Sell it and buy the EJ255 and EJ257, only they should be further developed in this series.
A typical chip with exhaust you can add about 30-40 hp. For more power to the EJ255 you need some modifications which, in general, are no different from those that have been recommended for the construction of fast EJ205, but it is better to use a turbine from STI – IHI VF48. This config will give about the 300+ hp.
If you still want to drive faster with EJ257 – the turbine configuration with TD05-18G might help.
How to Rebuild an EJ25 Subaru Engine
1999 Subaru Forester EJ25 Engine Removal