You've got to love those crazy German automakers, each trying to outdo the other for more of everything--power, torque, and speed. You might have thought that Mercedes-Benz's supercharged 5.4-liter V-8 engine would be powerful and torquey enough, with as much as 493 hp and 516 lb-ft of torque, but no. Mercedes has come up with a brand-new AMG V-8 that makes 503 hp at 6800 rpm and 465 lb-ft at 5200 revs, outstripping the V-10 its dreaded rivals from Munich put in the M5 and M6. M-B refers to this V-8 as a 6.3-liter unit, alluding to the engine fitted in the classic 300 SEL 6.3, but it's actually a 6.2-liter engine.
This is the first engine designed in-house by AMG, and it features a number of technical innovations. Essentially, it is an oversquare design with a bore of 102.2 mm and a stroke of 94.6 mm, with dual overhead camshafts and four valves per cylinder.
The engine block is cast in aluminum and features a so-called bedplate design, whereby the crankcase is split at the centerline of the crankshaft to optimize rigidity. Mercedes-Benz has opted to use a twin-wire-arc-sprayed coating on the cylinder walls, a new process that reduces friction and produces cylinder walls that are twice as hard as conventional cast-iron cylinder liners. DaimlerChrysler has been working on this technology for ten years, but this is its first production application. The engine uses a forged-steel crankshaft, crack-forged connection rods, and cast-aluminum pistons.
The intake and exhaust valves are continuously variable over a range of 42 degrees, and racing-style bucket tappets are used. Mercedes is very proud of the dual-length intake manifold, which has a pair of throttle butterflies sited as close to the intake valves as possible, yet another feature that is more commonly seen in racing engines. The entire unit weighs 439 pounds.
The engine will make its production debut in the ML63 SUV at the Frankfurt show and will be followed by an R63 AMG--that's right, Mercedes is building a sports version of the six-seater luxo-limo, which is another answer to a question nobody asked. Our first acquaintance with the engine was made in a much more exciting conveyance, a modified CLK-DTM. Sporting plastic windows, an even bigger rear wing, a stripped-out interior, and a shorter final-drive ratio, the CLK-DTM was wickedly fast around the Le Castellet track in southern France.
A large part of that speed came from the engine, which sounds like a NASCAR stocker and produces enough torque to pull giant redwoods. The engine will be mated to a seven-speed automatic in the production vehicles, but in reality a couple of gear ratios would do, because the engine pulls from tickover to the 7200-rpm cut-off. At 2000 rpm, 369 lb-ft of torque is available, with 413 lb-ft at 3000 rpm. This engine almost redefines the term "flat torque curve."
We can't wait to try out the new engine in a production car--although we think it will be more entertaining in the E- or C-class than in an R- or M-class. And, yes, the M-B engineers have said that their biggest engine fits in the next-generation C-class and in the SLK.