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Subaru reveals new boxer engine

Fuji Heavy Industries, the maker of Subaru cars, has launched its third-generation boxer engine in 1995cc and 2498cc naturally aspirated versions with lower CO2 emissions and 10 per cent better fuel economy.

Subaru Australia managing director Nick Senior says the first all-new petrol boxer since 1989 will arrive early next year in the 2.5-litre Forester.

"This is an exciting engineering development from FHI," says Senior who is in Japan for the announcement.  They're renowned for the durability of their engines and this new unit will take the sophistication to a whole new level."

Subaru Australia corporate affairs manager David Rowley says changing emission regulations is "one factor in the development" of the new engine.

"Several aspects of technology have moved on considerably in the last two decades, including lighter weight, high-strength materials, so it's logical to bring together many of these advances and apply them to a single all-new engine."

Rowley says the goals for the new engine were "the incorporation of new technologies and materials, emission and fuel efficiency gains, lighter weight and a completely modern platform on which to apply further enhancements as they become available".

There will be no effect on the turbo boxer engines "at this stage" and no plans for a smaller boxer petrol engine, he says.  "FHI advise the 2.0 and 2.5 account for their largest percentage of sales, hence the focus on these rather than (smaller engines)," he says.

The engines feature different bore and stroke configurations that increase displacement in the 2.0-litre model by a mere 1cc from 1994cc to 1995cc and in the 2.5-litre model from 2457cc to 2498cc.  The new engines also use a chain-driven cam instead of belt, which has longer life, but should make it slightly noisier.

Other changes include a longer stroke, compact combustion chamber, lighter moving parts, cooled exhaust gas recirculation system, intake/exhaust Active Valve Control System, tumble generator valve and a compact oil pump.

Subaru claims power in the Japanese domestic market version of the 2.0-litre boxer is down 1kW to 109kW but torque has been improved by 5Nm to 196Nm.  There are no power or torque figures available for the 2.5-litre version.

Rowley says the specification of the engines to be used in Australian vehicles will be announced when 2011 model Foresters are released.  FHI has built a new factory at its Gunma Oizumi Plant in Japan to produce the new engine.

Subaru has not released any plans for updates to its new boxer diesel engine, which Rowley describes as "going gangbusters".  Senior reported at the recent WRX/STI launch that diesel represents 28 per cent of Outback sales and 29 per cent of Forester since launch.

"Given that Outback sales are up 135 per cent year to date and Forester remains segment leader, it appears the manual-only diesel is kicking goals for us," Rowley says.

While Subaru is believed to be working on an automatic transmission for the boxer diesel, there is no timing yet.  "It's not even on the horizon at the moment," Rowley says.  "An automatic transmission might do better (in sales), but it isn't an option at the moment anyway."

Subaru 2.0L boxer

Engine: horizontally opposed 4-cylinder DOHC
Displacement: 1995cc
Compression ratio: 10.5
Bore x stroke: 84 x 90mm
Power: 109 kW
Torque: 196Nm