Fuji Heavy Industries, the owners of Subaru has developed a new and improved boxer engine for the Japanese auto brand. This will be the third generation model of the four-cylinder gasoline engine and it has been renewed for the first time since 1989. Accommodating this new engine, the company has built the new Gunma Oizumi Plant just for this purpose. Available in either in 2500 cc or 2000 cc forms, the engine still maintains lightweight, compact, low centre of gravity and good vibration balance. In addition to that fuel efficiency has improved by 10 percent.

Changes on the inside of this completely new engine include a more compact combustion chamber as well as a longer stroke, previously difficult due to chassis mounting conditions. There upgrades are said to improve combustion efficiency and help generate a sufficient mid-low speed torque with improved fuel efficiency. Fuel efficiency has been further optimized with improved intake port configuration and the addition of partitions inside the port, the use of TGV (Tumble Generated Valve) and EGR (Exhaust Gas Recirculation).

The engine also uses AVCS (Active Valve Control System) on both the intake and exhaust valves. The intake particularly will benefit from an intermediate lock system that allows valve timing to be advanced or delayed for precise control over intake and exhaust valve timing. Apart from that, the engine employs lighter moving parts such as pistons, connecting rods and a compact oil pump, which provides approximately 30 percent reduction in friction loss.

The cooling for the engine uses a separate circuitry for the block and the head, which again improves fuel efficiency and output levels. The company also pointed out that the new 2.0 litre boxer can produce 146hp and 196Nm of torque. The new engine is expected to debut with the 2011 Forester, due next year.