Subaru FB20 Engine Problems, Specs And Reliability

FB20 is a third-generation 2.0L flat-four engine, first released in 2010. It was constructed as a substitute for EJ motors. Though FB20 seems to be alike to EJ, it features a great number of differences.

It features a restyled aluminum cylinder block with a diminished piston bore. Growth of piston stroke helped to preserve the same offset, but increased torque at low revs.  In order to make the motor exterior look like EJ, Subaru used asymmetrical connecting rods.

FB20 keeps cylinder heads with DOHC 4-valve per cylinder. While EJ motors had 41° angle between intake and exhaust valves, the angle was decreased to 27° in FB. The space between camshafts was also reduced from 126 mm to 104 mm thanks to the usage of chain-driven camshafts instead of a timing belt. The small valve angle and bore reduce the level of emissions by providing a fewer amount of unburned fuel during a cold start.

Intake and exhaust camshafts feature AVCS, a variable valve timing system. The intake manifold is plastic and has 4 tumble-generation valves, which move the intake flow through electronic control to increase the motor power.

The use of lightweight pistons and connecting rods helped the brand to reduce friction losses by 28%. CO2 emissions were decreased by 4% while the engine consumes 10% less fuel. Thus, in comparison with EJ20, FB20 is more eco-friendly while having the same output and a broader torque strip.

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, 5W-20, 5W-30, 5W-40
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
– Real

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

Subaru FB20B

  • Displacement: 1,995 cc (2.0 L) DOHC
  • Bore x stroke: 84 mm × 90 mm (3.31 in × 3.54 in)
  • Compression: 10.5:1
  • 2011+ JDM Subaru Forester
  • Power: 109 kW (148 PS; 146 hp) at 6,000 rpm
  • Torque: 20 kg⋅m (196 N⋅m; 145 lbf⋅ft) at 4,200 rpm
  • 2012-2016 USDM Subaru Impreza and 2012-2017 Subaru XV
  • Power: 110 kW (150 PS; 148 hp) at 6,200 rpm
    Torque: 20 kg⋅m (196 N⋅m; 145 lbf⋅ft) at 4,200 rpm

Subaru FB20D

  • Used in the fifth generation Impreza sedan and hatchback.
  • Bore x stroke: 84 mm × 90 mm (3.31 in × 3.54 in)
  • Compression: 12.5:1
  • 2017+ Subaru Impreza and 2018+ Subaru XV
  • Power (JDM, USDM) : 113 kW (154 PS; 152 hp) at 6,000 RPM
  • Power (EUDM, AUDM): 115 kW (156 PS; 154 hp) at 6,000 RPM
  • Torque: 20 kg⋅m (196 N⋅m; 145 lbf⋅ft) at 4,000 RPM

Subaru FB20X

  • Displacement: 1,995 cc (2.0 L) DOHC
  • Bore x stroke: 84 mm × 90 mm (3.31 in × 3.54 in)
  • Compression: 10.5:1
  • Application: 2014+ Subaru XV Hybrid
  • Power: 160 hp (162 PS; 119 kW) at 6,000 rpm
  • Torque: 163 lb⋅ft (221 N⋅m; 23 kg⋅m) at 2,000 rpm

FB20 Engine Problems and Reliability

The first versions of FB motors (2010-2013) consumed too much oil. It’s considered that the reason is either in piston rings or damaged cylinder block. When the cylinder block is deformed, you need to acquire a fresh one. It’s necessary to acquire new piston rings or, at least, clean them up.

Moreover, to increase the lifespan of the catalytic converter and contribute to motor durability, it’s advisable to use high-quality fuel and monitor the level of engine oil. It’s better to use engine oil, which Toyota, Subaru, and Scion advise, to prevent the malfunction of the AVCS system, connecting rod bearing, and increased level of oil use. Another tip is to change the oil after every 5,000-7,500 kilometers. It’s still more frequent than auto manufacturers say, but it will contribute to motor durability.

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The information provided in this article is for general informational purposes only. The author and publisher make no representations or warranties of any kind, express or implied, regarding the accuracy, adequacy, validity, reliability, availability, or completeness of any information presented. The reader is advised to consult a qualified professional, such as a mechanic or dealership, before making any decisions related to their vehicle's engine oil or maintenance.

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