February
…som givetvis är något i hästväg. Med en 6,3l AMG V8 på 518hk och en nyutvecklad 7-stegad växellåda kommer säkerligen detta vara den snabbaste roadstern någonsin.
The SL63 AMG is powered by an AMG 6.3-liter V8 engine that features four valves per cylinder, variable valve timing, bucket tappets (rather than rocker arms) and a variable intake manifold. Sharing no parts with Mercedes-Benz V8 engines, the 6.3-liter engine was a completely autonomous development at AMG.
Built almost completely from a high-strength silicon-aluminum alloy, the cylinder bores make use of a twin-wire-arc-sprayed (TWAS) coating, a process that results in impressively low friction and running surfaces that are twice as hard as conventional cast-iron cylinders.
The 6.3-liter engine block boasts an especially rigid bedplate acting as the overall support of the main bearings (similar to a one-piece set of main bearing caps), cast-in steel reinforcements and a sturdy closed-deck layout in the cylinder head area. The high-flow intake and exhaust ports form a vertical straight line, helping the 6.3 AMG engine rev freely to more than 7,000 rpm, yet the highly flexible AMG engine still produces nearly 90 percent of its peak torque at only 2,000 rpm.
A finely balanced crankshaft with six counterweights spins in five main crankshaft bearings. The crankshaft counterweights feature heavy metal plugs – a detail usually found only in racing engines – which means they can be significantly smaller, increasing power by reducing rotational inertia and oil drag.
Each forged connecting rod is precisely “cracked” with the help of a laser beam, so the irregular fracture contributes to its strength when the two halves are clamped around the crankshaft. The connecting rods and lightweight pistons are matched for extremely close weight tolerances that contribute to smooth running at high speeds. Small nozzles in the engine block spray cooling oil onto the underside of each piston crown.
Källa: www.fast-autos.net