Engines FB25, FB25V Subaru

The automotive brand Subaru from the Japanese company of the same name is engaged in the production of passenger cars, commercial vehicles, individual components and assemblies for them, including engines.

Designers are constantly improving them.

In 2010, the world received a new FB25В boxer engine, later modified to FB25.

Features

Until 2010, Subaru equipped its cars with EJ series engines of 2 and 2.5 liters. They were replaced by FB type motors. The units of both series practically do not differ in technical parameters. The designers carried out work aimed at optimizing:

• the very design of the power plant;
• the combustion process of the fuel mixture;
• economic indicators.

Motors of the FB series comply with the norms and requirements for the amount of emissions of harmful substances in accordance with Euro-5.

Other features of the power plant of this series include:

• the presence of a mechanism for controlling the valve timing, which allows to increase the rated power;
• the timing drive is made in the form of a chain with gears;
• compact combustion chamber;
• increase in oil pump performance;
• separate cooling system installed.

Constructive nuances

Due to the design features of the boxer engine of the FB series, engineers managed to shift the center of gravity of the car as far down as possible. Thanks to this, the car becomes more manageable.

The developers equipped the power plant of the FB series with cylinders of increased diameter. Cast iron liners are installed in the cylinder block, made of aluminum. Their wall thickness is 3.5mm. To reduce friction, the engine was equipped with pistons with modified skirts.

The FB 25 power plant has two cylinder heads, each with two camshafts. The injectors are now placed directly in the cylinder head.

In 2014, the FB25 series ICE was modified. The changes affected the following:

• the thickness of the cylinder walls was reduced by 0.3 mm;
• pistons replaced;
• intake ports increased to 36 mm;
• a new injection system control unit has been installed.

Technical specifications

Subaru FB25B and FB25 engines are produced at the Gunma Oizumi Plant, owned by Subaru. Their main technical characteristics include:

FB25B	FB25
The material from which the cylinder block is made	Aluminum	Aluminum
Supply system	Injector	Injector
A type	horizontally opposed	horizontally opposed
Number of cylinders	Four	Four
Number of valves	16	16
Engine capacity	2498 cc	2498 cc
Power	170 to 172 horsepower	171 to 182 horsepower
Torque	235 N/m at 4100 rpm	235 N/m at 4000 rpm; 235 N/m at 4100 rpm; 238 N/m at 4400 rpm;
Fuel	Petrol	Petrol
Fuel consumption	From 8,7 l/100 km to 10,2 l/100 km depending on the driving mode	From 6,9 l/100 km to 8,2 l/100 km depending on the driving mode
Fuel injection	Distributed	Multipoint Serial
Bore	94 mm	94 mm
Piston stroke	90 mm	90mm
Compression ratio	10.0	10.3
Release of carbon dioxide into the atmosphere	220 g / km	From 157 to 190 g/km

According to experts, the minimum engine life is 300000 km.

Engine identification number

The engine serial number is the identifier of the internal combustion engine. Today there is no single standard that would determine the location of such a number.

For Subaru models, it is typical to apply an identifier to the platform, which is machined in the upper left corner of the rear wall of the power plant. That is, the engine number should be looked for at the junction of the unit itself with the transmission dome.

In addition, you can determine the type of internal combustion engine by the VIN code. It is applied to nameplates that are mounted under the windshield on the driver's side and on the rear bulkhead of the engine compartment on the passenger side. The type of power plant corresponds to the sixth position in the main identification number of the vehicle.

Vehicles with FB25В and FB25 engines

Since the advent of the FB25В and FB25 engines, they have been installed on a number of Subaru models.

The FB25В power plant has found its application on the Subaru Forester, including restyling of the 4th generation.

The following car models are equipped with the FB25 engine:

• Subaru Exiga;
• Subaru Exiga Crossover 7;
• Subaru Forester, starting from the 5th generation;
• Subaru Legacy;
• Subaru Legacy B4;
• Subaru Outback.

Disadvantages of FB25В and FB25 engines

Along with the many advantages of the FB25 engines, there are a number of disadvantages. Among them are the following:

• high oil consumption;
• coking of oil scraper rings;
• imperfect cooling system, which leads to engine overheating and oil starvation;
• Replacing spark plugs is labor intensive.

In general, it is recommended to operate vehicles with FB25 engines in a gentle mode. Otherwise, the resource is significantly reduced.

In the event of a failure of the power plant, a major overhaul will have to be carried out. In this case, it is recommended to contact a specialized service station. This will be the key to high-quality and professional engine restoration. When replacing parts, use only original parts.

Contract engine

The FB25 motor is repairable. However, the cost of components for the overhaul of internal combustion engines is quite high. Therefore, it is advisable to think about purchasing a contract engine.

Its price depends on the technical condition. Today it can be from 2000 US dollars.

Engine oil for FB 25

Each manufacturer recommends using the correct brand of engine oil for a particular type of engine. For power plants FB 25, the manufacturer advises the use of oil:

• 0W-20 Original Subaru;
• 0W-20 Idemitsu.

Additionally, oils are suitable for the engine, characterized by the following viscosity indicators:

• 5W-20;
• 5W-30;
• 5W-40.

The volume of oil in the engine is 4,8 liters. According to the manual, it is recommended to change the oil every 15000 kilometers. Experienced motorists advise doing this at around 7500 km.

Tuning or swap

The FB25 and FB25B engines were developed as an atmospheric power plant. Therefore, you should not try to install a turbine on it. This will lead to loss of reliability and failure of the unit.

As a tuning

• remove the catalyst from the exhaust system;
• increase the exhaust manifold;
• change the settings of the engine control unit (chip tuning).

This will add about 10-15 horsepower to your engine.

Due to the design features of the FB25 ICE, it is not possible to make a swap.

Reviews car owners

There are different reviews among Subaru Forester and Legasy car owners. Many are confused by the high oil consumption. In general, drivers like this car due to the reliability of the engine, handling, cross-country ability, Subaru's proprietary all-wheel drive.