Audi Showcases Lightweight Construction in High-Performance R8 GT

.2 kilograms (2.65 lb); thinner sheet metal and additional cutouts shaved 2.6 kilograms (5.73 lb) from the aluminum hatch over the 100 liter (3.53 cu ft) luggage compartment at the front of the car.

The long rear hatch is made of carbon fiber-reinforced plastic (CFRP)—an advantage of 6.6 kilograms (14.55 lb). The rear bumper and the sideblades of this same material save an additional 5.2 and 1.5 kilograms (11.46 and 3.31 lb), respectively. With its minimal weight and extremely high strength, CFRP is the ideal material for a high-performance sports car, and Audi has broad-based expertise in its use.

The engineers also fought to shave every possible gram of weight from the technical components of R8. They shaved one kilogram (2.20 lb) from the power brake system, four kilograms (8.82 lb) from the aluminum caps of the brake discs and 9.4 kilograms (20.72 lb) from the battery. The engineers also found 2.3 kilograms (5.07 lb) in the air intake module and 2.8 kilograms (6.17 lb) in the insulation of the engine compartment.

The interior also harbored substantial weight-savings potential. The new, lightweight carpeting accounts for 7.9 kilograms (17.42 lb); the bucket seats with a chassis of glass-reinforced plastic (GRP) account for 31.5 kilograms (69.45 lb). Numerous additional detailed measures targeted the interior, the exterior and the technology, such as higher-grade, lighter steel for the exhaust system’s tailpipes.

The 412 kW (560 hp) 5.2 FSI engine. Changes to the engine electronics coaxed an additional 26 kW from the modified ten-cylinder, which now produces 412 kW (560 hp) from a displacement of 5,204 cc. The torque curve peaks at 540 N·m (398 lb-ft) at 6,500 rpm, 10 N·m (7.38 lb-ft) more than in the production version. The V10 has a specific power output of 79.2 kW (107.6 hp) per liter displacement. Its power-to-weight ratio is 3.70 kilograms (8.16 lb) per kW or 2.72 kilograms (6.00 lb) per hp. The engine redlines at 8,700 rpm.

The long-stroke engine (bore x stroke 84.5 x 92.8 millimeters [3.33 x 3.65 in]), which is hand-built at the factory in Györ, Hungary, features a crankcase made of a aluminum-silicon alloy that is both lightweight and very strong. A bedplate—a frame for the crankshaft bearing bridges—further enhances its rigidity. The complete engine weighs only 258 kilograms (569 lb).

It is characterized by a cylinder angle of 90 degrees and dry-sump lubrication, which uses a highly efficient oil pump module. Both solutions lower the center of gravity and thus improve driving dynamics.

The crankshaft is designed as a common pin shaft. The connecting rods of the opposing pistons engage a common crankpin, resulting in alternating firing intervals of 54 and 90 degrees. This unique rhythm gives the V10 its distinctive sound. Two flaps in the exhaust system modulate its volume and tone as a function of load and engine speed.

The naturally aspirated engine consumes an average of 13.7 liters of fuel per 100 km (17.17 US mpg). The FSI gasoline direct injection system injects the fuel into the combustion chambers at up to 120 bar of pressure. The turbulent mixture cools the cylinder walls, enabling a compression ratio of 12.5:1. A variable intake manifold and the continuous adjustment of the chain-driven camshafts ensure that the combustion chambers are fully filled. Flaps in the intake ports facilitate the formation of the mixture by inducing a tumbling motion in the inflowing air.