The GT 86's engine is the result of a joint Toyota and Subaru development
programme that brings together their technical know-how and mutual passion for sports cars.
Toyota has added its D-4S injection technology to Subaru's new, horizontally opposed, naturally aspirated 1,998cc four-cylinder boxer engine. This system features separate twin injectors for both direct and port injection, and a high 12.5:1 compression ratio, increasing power and torque across a wide range of engine speeds without sacrificing fuel efficiency and environmental performance.
The flat-four engine has equal bore and stroke of 86.0mm and drives through either a six-speed manual or six-speed automatic transmission. The manual offers quick, precise shifts using a tactile, short-throw lever; the automatic transmission can be controlled using paddle shifts mounted on the steering wheel.
Power is distributed to the rear wheels via a limited slip differential to give the best possible grip in all driving conditions. The ABS and switchable vehicle stability control systems have been tuned specifically to deliver dynamic stability at the limit of the car's performance envelope with minimal electronic intervention to help preserve the purity of the driving experience.
FLAT-FOUR ENGINE.
A flat-four or horizontally opposed-4 is a type of four-cylinder engine, a flat engine with four cylinders arranged horizontally in two banks of two cylinders on each side of a central crankcase. The configuration results in inherently good balance of the reciprocating parts, a low centre of gravity, and a very short engine length. The layout also lends itself to efficient air cooling. This is no longer a common configuration, but some brands of automobile use such engines and it is a common configuration for smaller aircraft enginessuch as made by Lycoming, Continental and Rotax. Although they are somewhat superior to straight-4s in terms of vibrations, they have largely fallen out of favor because they have two cylinder banks thus requiring twice as many camshafts as a straight-4 (if an OHC rather than OHV or F-head configuration is used) while the crankshaft is as complex to manufacture. The low centre of gravity of the engine is an advantage. The shape of the engine suits it better for mid engine or rear engine designs. With a rear engine layout it allows a low-tail body while in front engine designs the width of the engine interferes with the ability of the front wheels to steer. The latter problem has not stopped Subaru from using it in its all-wheel drive cars, where the difficulty of fitting the short engine between the front wheels ahead of the front axle is compensated for by the ease of locating the transmission and four-wheel drive mechanisms behind it, between the front and rear axles.
The bore and stroke, the basic structure of this engine, have been reviewed to achieve a compact combustion chamber as well as a long stroke, which was difficult previously due to chassis mounting conditions in boxer gasoline engines. This allows high combustion efficiency, and generates a sufficient mid-low speed torque with improved fuel efficiency and practicality. Improved fuel efficiency has been achieved through optimization of intake port configuration and the addition of partitions inside ports, the use of TGV (Tumble Generated Valve), and the use of an EGR (Exhaust Gas Recirculation) cooler. AVCS (Active Valve Control System) is used on both intake and exhaust valves. For the intake side in particular, an intermediate lock system allows valve timing to be advanced or delayed for precise control over intake and exhaust valve timing, allowing maximum engine performance in output, fuel efficiency, and exhaust emission. The use of lightweight primary moving parts, such as pistons and connecting rods, and a highly efficient and compact oil pump provides an approximately 30% reduction in friction loss and improves fuel efficiency and revolution response. Cooling has been optimized by using separate engine cooling circuitry for the block and the head, resulting in improvements in fuel efficiency and output characteristics.
ADVANTAGES OF HORIZONTALLY OPPOSED ENGINE.
- Compared to in-line engine and V-type engine, the height of horizontally opposed engine is lowered, allowing a lower center of gravity for the entire vehicle.
- The lightweight, compact design and symmetrical layout allow a smaller yaw moment of inertia.
- The pistons on the left and right sides move in symmetrical opposition, cancelling out any vibration. This allows a smooth revolution feeling with little vibration. In addition, since no balancer shaft is required, the weight increase of the engine is minimized.
- Since the engine is sitting low, strong forces from the front such as a head-on collision will result in the engine being driven underneath the car. As a result, there is a reduced risk of the engine being forced into the cabin and injuring passengers.
- Since the engine is sitting low, there is ample space between the engine and the hood. This space will absorb some of the force in the event of a collision, reducing injury to pedestrian.
- http://www.tune86.com/toyota-gt-86-technical-specs-info-details
- http://en.wikipedia.org/wiki/Toyota_86
- http://www.youtube.com/watch?v=e_1UP29lGt0
- http://www.youtube.com/watch?v=1G2AggjJCy8
- http://en.wikipedia.org/wiki/Flat-four_engine
- http://www.zercustoms.com/news/2010-Subaru-Boxer-Engine.html
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