Subaru FB25 Engine Problems And Reliability

The atmospheric gasoline engine FB25 with a volume of 2498 cm3 was launched by the Japanese concern Subaru in 2010. And today its production is still ongoing.

Over the past ten years, it has been installed on several Subaru cars. In particular, we are talking about models such as Exiga, Forester, Legacy and Outback.

Description and main features

The FB25 engine has a horizontally opposed design. This means that the cylinders here are arranged in 2 rows, and the angle between them is 180°. In addition, in such power units, opposing pistons reach top dead center at the same time during movement.

The cylinders in the FB25 (4 in total) are made of aluminum. It should also be noted that in this engine, in fact, 2 cylinder heads (and each of them has 2 camshafts). And the total number of valves here is 16.

Also, among the important features of this internal combustion engine, it is worth highlighting the proprietary variable valve timing system (it is called Subaru Dual AVCS), timing chain drive and distributed fuel injection.

There are two versions of the FB25: the first (before 2014) develops up to 172 hp, and the second (after 2014) – up to 175 hp. Plus, they differ in compression ratio: as part of the 2014 modernization, it was increased from 10 to 10.3.

Tuning prospects

The easiest tuning option for the FB25 engine is reprogramming the ECU. A few extra horsepower can be obtained by a similar method. But, of course, such an increase cannot be called significant.

If, along with chipping the control unit, the exhaust system is also improved, then in the end it is possible to achieve an indicator of about 190 hp.

It should also be added that experts do not recommend installing kit kits with a turbine on the FB25 engine. Because of such experiments, the motor will lose a lot in reliability and resource.

Applicability of FB25 engine

  • Subaru : Forester (2010-н.в.), Legacy (2012-н.в.), Exiga (2012-2015)
Volume (cm3)2498
Power (hp)172/185
Torque235/240 Nm
Timing driveChain
Environmental classEuro 5/6
Fuel typeGasoline AI-95
ICE featuresDOHC
Supply systemInjector/Direct Injection
hydraulic liftersNo
Cylinder blockAluminum H4
cylinder headaluminum 16v
Cylinder diameter94 mm
piston stroke90 mm
Compression ratio10/12
Phase regulatordual stroke
Engine oil4.8 0W20
Average resource250 000 km.

Disadvantages and problems of the FB25 engine

The owner of the FB25 engine needs to carefully monitor the quality of the gasoline used. Bad fuel will destroy the catalytic converter very quickly.

On top of that, only the oil recommended by the manufacturer should be poured into this motor. Otherwise, everything can end up turning the connecting rod bearings of the crankshaft.

And the oil level is also of fundamental importance here. Even a small drop in this level leads to the fact that the internal combustion engine starts to work very noisily.

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