Subaru EJ25 Engine Specs And Problems

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 at 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 a 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 positions 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 was finalized, after which he received the lightweight pistons, modified intake ports, a plastic intake manifold, the other spark plugs, and refined system i-AVLS, facilitated by the exhaust system.

EJ25 Engine Specs

Manufacturer Gunma Oizumi Plant
Also called Subaru EJ25
Production 1996-present
Cylinder block alloy Aluminum
Configuration Flat-4
Valvetrain SOHC
2 valves per cylinder
DOHC
4 valves per cylinder
Piston stroke, mm (inch) 79 (3.62)
Cylinder bore, mm (inch) 99.5 (3.86)
Compression ratio 8.2 (EJ257)
8.4 (EJ255)
8.7 (EJ257)
9.5 (EJ25D 1996)
9.7 (EJ25D 1997-1999)
10.1 (EJ251/EJ252/EJ253)
10.7 (EJ254)
Displacement 2457 cc (338.8 cu in)
Power output (horsepower) 224 kW (155 HP) at 5,600 rpm
239 kW (165 HP) at 5,600 rpm
298 kW (165 HP) at 5,600 rpm
300 kW (173 HP) at 5,600 rpm
224 kW (170 HP) at 6,000 rpm
239 kW (210 HP) at 5,600 rpm
298 kW (230 HP) at 5,600 rpm
300 kW (250 HP) at 6,000 rpm
239 kW (265 HP) at 6,000 rpm
298 kW (280 HP) at 5,600 rpm
300 kW (300 HP) at 6,000 rpm
Torque output 190 Nm (385 lb·ft) at 2,800 rpm
220 Nm (393 lb·ft) at 4,000 rpm
226 Nm (413 lb·ft) at 4,400 rpm
225 Nm (406 lb·ft) at 4,000 rpm
238 Nm (385 lb·ft) at 2,800 rpm
320 Nm (393 lb·ft) at 3,600 rpm
320 Nm (413 lb·ft) at 3,600 rpm
339 Nm (406 lb·ft) at 3,600 rpm
347 Nm (393 lb·ft) at 2,800 rpm
392 Nm (413 lb·ft) at 4,000 rpm
407 Nm (406 lb·ft) at 4,000 rpm
Redline
HP per liter 63.1
67.2
67.2
70.4
69.2
85.5
93.6
101.8
107.9
114
122.1
Fuel type Gasoline
Weight, kg (lbs) 120 (500)
Fuel consumption, L/100 km (mpg)
-City
-Highway
-Combined
for WRX STI VA
14.0 (11)
8.4 (21)
10.4 (16)
Turbocharger Naturally aspirated
Mitsubishi TD04L (WRX/Forester)
IHI VF39 (STI)
IHI VF41 (Forester STI)
IHI VF45 (Legacy GT)
IHI VF46 (Legacy GT)
IHI VF48 (STI)
IHI VF52 (WRX)
Oil consumption, L/1000 km
(qt. per miles)
up to 1.0
(1 qt. per 600 miles)

Recommended engine oil

for Subaru Impreza

0W-30, 5W-30, 5W-40, 10W-30, 10W-40
Engine oil capacity, L (qt.) 4.0 (EJ25D, EJ25 2007+)
4.5 (2000-2007)
4.3 (WRX/STI 2000+)
Oil change interval, km (miles) 5,000-10,000
(3,000-6,000)
Normal engine operating temperature, °C (F)
Engine lifespan, km (miles)
-Official information
-Real

250,000+ (150,000)
Tuning, HP
-Max HP
-No life span loss
350+

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, the 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. 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 a 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 was replaced by FB25, and the turbo FA20.

Subaru EJ25 Oil Capacity

The Subaru EJ25 engine requires 4.4 quarts of 0W-30 oil with a filter replacement.

Subaru WRX STI 2003 Engine Sound

What Cars Have A EJ25 Engine?

  • Subaru Impreza (WRX/STI)
  • Subaru Forester
  • Subaru Legacy/Outback
  • Subaru Baja
  • SAAB 9-2X

Subaru EJ25 Engine Problems And Reliability

  • Turbo failure
  • Ringland problems
  • Rod bearing failure

EJ25 2.5 liter engine has the same problems as 2.0 liter. About them, you can read here.

The EJ255 is a good all-around engine. The 2.5L turbo flat-four delivers outstanding performance, with its own distinct sounds to match. There’s also a lot of information and aftermarket help for the EJ255. EJ255s are responsive to modifications, but they have their limits as well. If you want to modify your Subaru 2.5L STI, stick with a conservative tune or upgrade the internals.

Subaru 2.5 EJ25 Engine Tuning

Exactly as with the 2-liter EJ20, EJ25, and many other naturally aspired 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 300+ hp.

If you still want to drive faster with EJ257 – the turbine configuration with TD05-18G might help.

Dan Hoffman

Dan is a co-founder of Engineswork. He knows everything about internal combustion engines. Ask your questions in comments down below this article - he will be glad to help you anytime.

Recent Posts