The redeveloped naturally-aspirated 5.2-liter V10 in the R8 GT Spyder endows the open-top high-performance sports car with excellent performance. The sprint from zero to 100 km/h (62.14 mph) is possible in 3.8 seconds; from zero to 200 km/h (124.27 mph) takes just 11.5 seconds. And acceleration remains brisk until the top speed of 317 km/h (196.97 mph) is reached.
Changes to the engine management coaxed an additional 26 kW (35 hp) from the ten-cylinder, which now develops 412 kW (560 hp) from a displacement of 5,204 cc. The latter is achieved at an engine speed of 8,000 rpm. The maximum engine speed is 8,700 rpm, and the torque curve reaches its peak of 540 Nm (398.28 lb-ft) at 6,500 rpm. The V10 achieves a specific output of 79.2 kW (107.6 hp), giving the R8 GT Spyder a power-to-weight ratio of 3.98 kilograms (8.77 lb) per kW, or 2.93 kilograms (6.46 lb) per hp.
The handcrafted long-stroke engine (bore x stroke 84.5 x 92.8 millimeters [3.33 x 3.65 in]) features a cylinder angle of 90 degrees. Its crankcase is made of a lightweight, yet extremely strong, aluminum-silicon alloy. A frame for the bottom bearing bridges of the crankshaft further enhances its rigidity. The V10, whose cylinder head covers are painted red, weighs only 258 kilograms (568.79 lb). The dry-sump lubrication system with its highly efficient pump module allows the engine to be installed low. It also ensures a reliable supply of oil to the engine even under extreme lateral acceleration.
The crankshaft is a common pin construction. With this design, the connecting rods of the opposing pistons engage a common crankpin, resulting in alternating firing intervals of 54 and 90 degrees. This rhythm gives the V10 its fascinating sound. Two flaps in the exhaust system modulate its volume and tone depending on load and engine speed.
The 5.2-liter FSI consumes an average of 14.2 liters of fuel per 100 km (16.56 US mpg). The fuel is direct-injected into the combustion chambers at pressures below 120 bar. The swirling mixture cools the cylinder walls, allowing a compression ratio of 12.5:1. A variable intake manifold and the continuous adjustment of the chain-driven camshafts ensure complete charging. Flaps in the intake ports induce a tumbling motion in the inflowing air, thus further optimizing the mixture formation.
Gear changes in the R8 GT Spyder are performed via the standard R tronic sequential manual transmission. The electrohydraulic clutch and gearshift unit receives its commands by wire, in other words, electronically. It changes the six gears at lightning speed – in approximately one-tenth of a second at high load and engine speed – even faster than in the production Spyder. The double-plate clutch is only 215 millimeters (8.46 in) in diameter, fitting for the low installation position of the engine.
The R tronic management offers three operating modes – an automatic mode with Sport and Normal characteristics, and two manual programs. In the manual programs, the driver changes gears using the joystick on the center tunnel or the two paddles on the steering wheel. For spectacular starts, there is launch control – a program that manages full-on acceleration with high engine speed and minimum tire slip.
Power flows from the R tronic via a propshaft to the quattro permanent all-wheel drive. Its centerpiece is a viscous coupling at the front differential. The viscous coupling comprises a package of round disks that rotate in a viscous fluid and are geared in an alternating pattern: for every one that is connected to the propshaft via the housing, the one next to it is connected to the output shaft leading to the front axle.
Under normal driving conditions, the viscous coupling distributes the power between the front and rear axles in a 15:85 ratio. This harmonizes perfectly with the 43:57 weight distribution in the R8 GT Spyder. The high-performance sports car is rear-biased, providing a key added measure of grip, stability and cornering speed compared with its rear-wheel-drive rivals.
If slip occurs at the rear axle, the disks in the coupling rotate at different speeds; the oil becomes more viscous as a result of its internal friction. By picking up the other clutch disk of each pair, greater torque is transferred to the shaft leading toward the front axle – within a matter of milliseconds, the coupling is able to divert another 15 percent of the power to the front. A mechanical limited slip differential at the rear axle further increases the traction. It provides up to 25 percent lockup when accelerating and up to 40 percent on the overrun.
The equipment and data specified in this document refer to the model range offered in Germany. Subject to change without notice; errors and omissions excepted.