Subaru Announces Worlds First Turbodiesel Boxer Engine

Photos

Announced at Paris: Subaru will be making a diesel! (Photo: Subaru)

Everything from the Impreza upwards has a boxer engine. (Photo: Subaru)

Boxer layout has many advantages, from packaging, to smoothness and size. (Photo: Subaru)

Note the injector layout for the diesel system. (Photo: Subaru)

Turbo, injectors and 180-degree layout. (Photo: Subaru)

Odd Layout Has Its Advantages

Though the refresh of the Legacy and Outback midsize models were key to the brands display at this years Paris motor show, theres much bigger news back at home camp. Alongside these introductions, Subaru confirmed that it would be building its own turbodiesel engine, something that its never done before. And while diesel power is a hot topic, Subarus oil burner will be different: its making a huge splash by choosing to defy convention in developing the worlds first boxer (horizontally-opposed) diesel engine.

Subaru and the boxer engine have a lengthy history; much like the Japanese brands symmetrical all-wheel drive system the boxer engine has become a hallmark of the brand. Currently, every vehicle sold in North America is powered by either a horizontally opposed four, or in upper-model vehicles a  horizontally opposed six. There are a few exceptions, most of which are domestic-bound models such as the G3X Justy (a Daihatsu), the Traviq (an Opel Zafira), and its own, tiny kei-segment R1 and R2 which use miniscule, sub-one-liter inline-fours.

Like the rotary to Mazda, Subaru is one of two mainstream automakers that use horizontally-opposed engines. Porsche currently has this layout in its sports car products (Cayman, Boxster, 911) and previously Chevrolet (Corvair), Alfa Romeo (Alfasud, Sprint, 33 and early versions of the 145), Lancia (Fulvia), Ferrari (Berlinetta Boxer, Testarossa, 512TR), Volkswagen (Beetle, Bus, 411/412, Karmann Ghia, SP2, Thing, etc.), Citroen (2CV), and BMW motorcycles - to name a few - used boxer-type engines.
Incidentally, the engine type was invented by Karl Benz in 1896.

For the past 34 years, Subaru has chosen to perfect its boxer engine recipe, sticking with the unique flat, 180-degree cylinder angle layout due to its many advantages. Subarus engines have long been lauded for their smoothness; because the pistons are positioned on a horizontal plane, the vibrations that they make essentially cancel out. This, combined with the latest common-rail turbodiesel technology should help to make Subarus diesel boxer one of the smoothest diesels ever made.

Of course, there are other advantages that lend themselves to mating diesel with the boxer configuration. Because the crankshaft is directly in the center of the engine, on the same plane as the pistons and cylinder, the crankshaft itself is well supported, allowing it to easily cope with the massive pressures that diesel engines are subjected to. Another benefit is that the engine can be very compact, and very short, which means that it can be positioned closer to the ground for a lower center of gravity. This has less to do with the performance of the engine itself, and more to do with the effect of the dynamics and handling.

But aside from confirming this fact, Subaru has kept its lips sealed about the particulars of the engine, namely its displacement, the power it generates, emissions and fuel consumption, plus what models it will be available in. It has been rumored that Subarus diesel will be able to meet ultra-strict North American emissions standards, which should help give Subaru a massive edge over its competitors here if it chooses to take advantage. The engine will make its debut at the Geneva Motor Show this spring, and should on sale by the end of the next year.