Subaru FB20 Engine

  1. Specifications
  2. Overview, problems
  3. Performance tuning

Subaru FB20 engine specs

Manufacturer Gunma Oizumi Plant
Also called Subaru FB20
Production 2010-present
Cylinder block alloy Aluminum
Configuration Flat-4
Valvetrain DOHC
4 valves per cylinder
Piston stroke, mm (inch) 90 (3.54)
Cylinder bore, mm (inch) 84 (3.31)
Compression ratio 10.5
10.8 (Hybrid)
Displacement 1995 cc (121.7 cu in)
Power output 109 kW (148 HP) at 6,000 rpm
110 kW (150 HP) at 6,200 rpm
119 kW (162 HP) at 6,000 rpm
Torque output 196 Nm (145 lb·ft) at 4,200 rpm
197 Nm (145 lb·ft) at 4,200 rpm
221 Nm (163 lb·ft) at 4,200 rpm
Redline 6,400
HP per liter 74.2
Fuel type Gasoline
Weight, kg (lbs)
Fuel consumption, L/100 km (mpg)

Subaru Forester 2.0
10.4 (22)
6.7 (35)

8.0 (29)
Turbocharger  Naturally aspirated
Oil consumption, L/1000 km
(qt. per miles)
up to 1.0
(1 qt. per 600 miles)
Recommended engine oil 0W-20
Engine oil capacity, L (qt.) 4.8 (5.1)
Oil change interval, km (miles) 5,000-10,000
Normal engine operating temperature, °C (F)
Engine lifespan, km (miles)
-Official information

200,000+ (120,000)
Tuning, HP
-Max HP
-No life span loss

The engine is installed in Subaru Forester
Subaru Impreza/XV

Subaru FB20 engine reliability, problems and repair

In 2010 the successor of naturally aspirated EJ204 was presented. This motor has the same flat-4 boxer configuration, and its capacity is 2 liter. FB20 cylinder block is aluminum and has open deck, with cast-iron sleeves, cylinder diameter is 84 mm, and piston stroke is 90 mm. Now it is undersquare engine. Also FB20 has got the improved cooling system, new lightweight pistons and asymmetric connecting rods .
On steel two-layer cylinder head gaskets there are two aluminum heads with two camshafts, 4 valves on the cylinder. FB20 uses variable valve timing system AVCS on intake and exhaust camshafts. These camshafts are put in action by means of timing chain, which is non-serviceable according to Subaru statement. On the intake part there is plastic intake manifold with TGV valves, which improves ecological index. FB20 uses new headers and more straight exhaust system.
This motor is usually called FB20B and it showed 150 horsepower at 6,200 rpm, and torque 197 Nm at 4,200 rpm.
In 2013 Subaru XV Hybrid was represented, it used FB20X motor. Its difference is the use of an additional electric motor. Power of this motor together with electric motor reaches 162 HP at 6,000 rpm, and torque to 221 Nm at 4200 rpm.
FB20 firing order is 1-3-2-4.
Also 2.5-liter FB25 was created on the basis of FB20.

Subaru FB20 engine problems and malfunctions

1. High oil consumption. FB20 used to have this shortcoming till 2013. Most likely the problem is in piston rings or in the defective cylinder block. Yes, there were such cases. If your cylinder block is curved, then you should buy a new one. You should replace piston rings or try to make decoking, it will help for some time.
Besides, in order to enjoy long operating period of catalytic converter, you should use good gasoline and watch the level of engine oil, it is rather important for this engine . Moreover, use the engine oil which is recommended by Subaru/Toyota/Scion. Otherwise you will face problems with AVCS system, high oil consumption, connecting rod bearing failure and other troubles. It is also desirable to change engine oil more often, than it is recommended, for example every 5000-7500 km. It will increase its resource.

Subaru FB20 engine tuning

FB20 N/A

FB20 is the classical modern motor, it was created as the economic and eco-friendly motor. Besides, it has tendency to high consumption of engine oil and can work at high temperatures, therefore you should not dream of building powerful naturally aspirated FB20.
You can adjust ECU more aggressively and install aftermarket exhaust system. It will give additional horsepower and you will get pleasant Subaru sound.


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