Subaru Impreza RB320oc Owners Club RB320

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Unveiling the hidden beauty of Subaru's mechanical parts

Mechanical Parts


Subaru pursues the ideals of technology to create a car that is fun to drive. This is the Subaru's development philosophy.

This does not mean aiming for and developing designs for easy-to-make, low-cost parts. The foremost aim is to create an ideal car that provides people with driving pleasure and, keeping the ideal in mind Subaru's engineers then pursue ease of manufacture and cost-reduction. It is an effort that Subaru must tirelessly and endlessly uphold to create the ideal car.

The only way to offer better vehicles and to provide people with an enjoyable motoring lifestyle is through this method of technical development. Subaru's engineers have always held this belief.

Accordingly, Subaru vehicles, like other landmark cars in history, has its own originality and distinctiveness. This can even be called individuality, but Subaru has not always sought this.

The symbol of the individuality of Subaru vehicles is its Horizontally-Opposed Engine. At the very center of the Horizontally-Opposed Engine is the crankshaft, which revolves at high speed. Now I am going to discuss the crankshaft.

As most people are aware, the crankshaft is a part that converts the up and down motion of the piston through a connecting rod into rotational motion. The crankshaft shoulders a tremendous force of nearly 10 tons in an instant. In addition, the crankshaft commonly revolves more than 5000 times per minute. The rev counter on the instrument panel actually indicates the number of revolutions of the crankshaft.

Obviously the crankshaft must be a strong, durable, and because it revolves at high speed, a precision of microns is required. For this reason, the crankshaft is the most valued part in the engine. The crankshaft is made in a high-precision process forged from high- hardness chrome molybdenum steel. The crankshaft is called the foundation stone or main support of the engine.

While the explanation of the crankshaft until this point has been generalized, in the Horizontally-Opposed Engine the structure of the crankshaft is a little different.

Noriaki Suzuki, who is in charge of crankshafts at the Subaru Engineering Division explains, "The outward appearance, the crankshaft of the 4-cylinder Horizontally-Opposed Engine is considerably shorter than that of an inline engine. An inline 4-cylinder engine places all four cylinders in a straight line and therefore the crankshaft has a length to suit this arrangement. However, the 4-cylinder Horizontally-Opposed Engine has two banks of two cylinders, rather than a single row of four. Therefore, compared to the inline four engine, the crankshaft for the Horizontally-Opposed Engine is shorter. In addition, for the crankshaft of an inline engine, a weight called a counterbalancer is necessary. On the other hand, since the parts in Horizontally-Opposed Engine are arranged engine parts symmetrically, the balance is good and does not need a weight. This makes the crankshaft of the Horizontally-Opposed Engine both short and light. From a basic technological standpoint, the lightness of a part that revolves at high speed is a distinct advantage."

Making a part smaller and lighter is a also technical advance. From this perspective he says that the crankshaft of the Horizontally-Opposed Engine has significant advantages. A number of excellent features are derived from the fundamental differences of the Horizontally-Opposed Engine. At the same time, some disadvantages also exist.

"Since it is short, rigidity is difficult to maintain. This is a technical area in which we need to apply our efforts."

Mr. Suzuki appears animated when asked further questions about the crankshaft of the Horizontally-Opposed Engine.

"The development of the crankshaft was not merely a matter of developing the best crankshaft. Please don't get me wrong. At Subaru, we first consider what kind of car we want to develop. This is a comfortable car, fun to drive, with room for luggage and a high level of safety. After these overall concepts have been considered, then we decide what kind of engine and which size and width is suitable. After deciding on the size of the engine, we consider the bore and stroke, which are important considerations related to combustion. After this we can begin to consider the planning requirements of the crankshaft."

The crankshaft does not have an independent existence. Even though it is an important engine part, it is necessary to examine how the part will fit into the overall concept of a car. This is because Subaru seeks technology that will serve people.

This is Subaru's car creation philosophy and this even has a major influence over the development of the crankshaft. I was deeply impressed by the Subaru development stance.

The crankshaft must revolve at high speed, therefore to achieve rotational balance, the web is shaved to adjust for the weight, and the portions of the crankshaft that touch the metal and the connecting rod are well polished. This is the texture of the steel, which has a bright, shiny surface.

Mr. Suzuki concluded with the following surprising account.

"This is the crankshaft for the 2 liter Legacy. However, the initial designs were prepared 15 years ago. Developed for the first generation Legacy, these designs have not been changed since. In this intervening period, the turbocharger has been added as well as a racing engine for the World Rally Championship that spins at 8000 revolutions, and this crankshaft handles the job with precision. This crankshaft has not yet reached its limits and there is still much untapped potential. The technical ability and insight of the earlier engineers that designed this part is to be admired for achieving such a marvelous feat. We in this generation of Subaru engineers must also strive to achieve an even greater level of excellence."

Another Subaru secret unveiled.

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Richard Burns

Subaru rally legend, Richard Burns Britain's only FIA World Rally Champion died in November 2005 of brain cancer at the age of 34.

Click here for more information on the 2001 World Rally Champion.

RB320 Features

  • 6,000 of extra equipment
  • 320PS/450Nm Prodrive tuned
  • build limited to 320 units
  • finished in Obsidian Black
  • bespoke 18" alloy wheels
  • unique numbered tax disc holder
  • Prodrive tuned suspension system with Bilstein dampers, Eibach springs & rear ARB
  • lowered ride height
  • polished s/steel mesh front grille
  • STI front lip spoiler
  • STI quickshift gearchange
  • STI side sill plates
  • RB branded gear knob
  • RB branded car mats
  • RB exterior badging
Click here for full list