I've traveled to Spain for the AMG press event. I've driven the cars. I've talked to the public relations people, the marketing folks, the engine guru they hired back from Porsche, and a member of the board. After all of that, I still don't understand why AMG and Mercedes-Benz have designed a bespoke 6.2-liter V8 engine, which they are calling a 6.3L, that commemorates an AMG racing victory in 1971 with a 6.3-liter V8 engine that was actually a 6.8L. Confused? I'll try to explain.
In the beginningAMG has been around for nearly 40 years. It was started in 1967 in an old sawmill in Grossaspach, Germany, by Hans Werner Aufrecht and Eberhard Melcher. The fledgling company took its name from the A and M of the founders' last names and the G from the town where they were located. AMG's purpose was simply to tune Mercedes-Benz models to higher performance levels. Mercedes-Benz had contested a few international rallies during the 1960s, but hadn't been a real force in racing since the heyday of the 300SL sports car almost a decade earlier. There were no other tuners specializing in Mercedes-Benz at that time, yet the choice was an obvious one for the two former Mercedes-Benz engineers who started the company. They also knew that there was a new Mercedes model on the horizon that promised to put both AMG and Mercedes-Benz squarely in the performance game.
300SEL 6.3In 1965, Mercedes-Benz replaced its "fin-back" sedans with the W108 and W109 series "square-backs." These roomy and comfy six-cylinder four-door sedans had good performance, especially the six-cylinder 300SEL model with its 185 bhp. There was more coming. Mercedes-Benz engineer and racing fanatic Erich Waxenberger and Mercedes Racing Chief Rudolf Uhlenhaut looked at the huge 6.3-liter V8 from the 600 Pullman Limousine and realized that it would just fit in the 300SEL's body shell. The 6.3L had a cast-iron block and aluminum heads with single overhead camshafts. With 6,329cc, the V8 made 300 bhp and 434 lb-ft of torque. The resulting two-ton 300SEL 6.3 would accelerate from zero to 60 mph in 7 seconds and could hit an aerodynamically limited 137 mph. With a stock limited-slip rear axle (very necessary) and four-wheel disc brakes (even more necessary), reviewers quickly ran out of superlatives with which to describe the car. Racer/engineer Waxenberger brought one to Macao off the coast of China and won a six-hour touring car race in 1968. With approval from the company, the charismatic engineer prepared three cars for the 24-hour race for touring cars that would take place at Spa in Belgium in July 1969. This was the first "official" race participation of the German company in 15 years. The cars were fast in practice, but the tires couldn't hold up to the high speeds of the heavy sedans and the cars were withdrawn before the start of the race. Waxenberger continued his development of the big machines, fitting larger wheels and tires, fender flares, and boring the engine out to raise its capacity to 6,834cc.
Enter the guys from GrossaspachWith a looming energy crisis and uncertainty in the Daimler-Benz boardroom, racing was curbed in the early 1970s. It had to be frustrating for Waxenberger and his crew of racers to know that they had a potent racing machine in the big-engine sedan. What happened next was inevitable: Under-the-table equipment and know-how created by Waxenberger's team showed up at AMG's sawmill to help out some fellow racers. Hans Aufrecht bought a wrecked 300 from a local doctor and set about building a racecar. They built up a 6.8-liter V8 engine that made a reliable 398 bhp at 5600 rpm and went to test the car at Hockenheim, two weeks before the 24-hour race for touring cars at the Spa-Francourchamps circuit in Belgium. Then disaster struck at Hockenheim when test driver Helmut Kelleners crashed the car in a big way, and AMG's small group of overworked employees had to work day and night to repair the car for its debut. New drivers were found. They were German go-kart champion Hans Heyer and veteran driver Clemens Schickendanz. The pair used practice and qualifying rounds to work out fuel and tire consumption, and during the race counted on the pit crew of six to keep the car going. Their big red sedan finished the race first in class and second overall, and the AMG legend was born. The AMG car entered a total of only eight races, and although it was fast (it was clocked at 176 mph on the Hunaudieres Straight at the four-hour touring car race at Le Mans), it never repeated its earlier podium success. Racing rules changed in 1972, setting a displacement limit of 5.0 liters for touring cars. Its racing career over, in 1973 the AMG-Mercedes-Benz 300SEL 6.8 race car was stretched three inches, given a full 428-bhp engine and special high-speed tires, and was used by French aircraft manufacturer Matra as a stable platform to test the landing gear of jet fighter aircraft.
AMG prospersThe success of the AMG entry at the 1971 Spa race didn't go unnoticed. Customers who wanted more from their Mercedes-Benz models gave the company plenty of tuner work providing uprated engines, light-alloy wheels, bigger brakes, and tighter suspensions. In 1976, the company and its 40 employees moved to a larger facility in Affalterbach and increased the size of its staff. Meanwhile, Mercedes-Benz provided AMG with the occasional "special project," including preparing four 280E sedans for the 1977 London-Sydney marathon rally that were listed as private entries, but had significant support from the factory. The Mercedes-Benz entries prepared by AMG finished first, second, sixth and eighth overall in the grueling 19,000-mile event. Racing was still in AMG's plans, and in 1980 an AMG-Mercedes 450 SLC won a European touring car race at the Nrburgring in Germany.
A business of road carsAlthough AMG was well-established as a Mercedes race preparation company, its founders realized that the company's bread and butter would come from putting that racing image and heritage onto the street. It began developing a line of specialized road cars, stuffing big V8 engines into usually staid Mercedes-Benz body shells to create electrifying performance. First came the 280 CE 5.0 AMG in 1983 with a 276-bhp V8. In 1984, the company produced the 500 SEC AMG with four-valve cylinder heads that made 340 bhp, producing a car the size of a small cottage that would top 160 mph. In 1985, AMG opened its second factory and welcomed its one hundredth employee.
The company's next car, built in 1986, would forever sear the AMG name into American Mercedes-Benz lore. AMG took the midsize 300E sedan, pulled out its 177-bhp inline six-cylinder and filled its engine bay with a 5.5-liter V8 engine with four valves per cylinder making 360 bhp. It was wild, it was outrageous, it would accelerate to 60 mph in 5.5 seconds, and its top speed was better than 180 mph. It put serious sports cars like the Porsche 928 and Ferrari GTO onto the trailer, yet it was a practical four-door sedan that could take the kids to school and the dog to the groomer. American enthusiasts christened it the "Hammer" and the name stuck. Other Mercedes-Benz tuners were now on the scene, building their own versions of Mercedes-Benz fantasy, but the best known and most respected tuner remained AMG.
Back to racingAfter a mediocre season of world championship rallying with the big 500SLC coupes in 1980 (one win at the rough Ivory Coast Rally, two second places and two thirds), the Mercedes-Benz board again pulled the plug on official competition activities. This was unfortunate, as once again a new potentially successful racer was sitting in the wings. This was the new small 190E sedan, introduced in Europe in 1982 and to the United States in 1984. Its 2.3-liter four-cylinder engine made a usable 121 bhp, and its objective was to compete on the market with the BMW 3 Series. The small Mercedes was significantly enhanced in 1984 by the introduction of the 190E 2.3-16 whose 16-valve cylinder head designed by Cosworth helped the 2.3-liter four-cylinder engine make 167 bhp at 5800 rpm. The car was fast, handled well, and would have formed the perfect basis for a racing car, if only the parent company hadn't nixed all racing. Something had to be done.
Just as in 1971, Hans Aufrecht and AMG were ready to take the lead. In 1986, 190E 2.3-16 models were competing in the German Touring Car Championship (called DTM for Deutschen Touringwagen-Meisterschaft) with AMG engines, winning at the Nrburgring and at Avus. The 1986 season championship was won by a British Rover, but the 1987 championship went to BMW. This win by archrival BMW was the best thing that could have happened to AMG as suddenly a lot more "back-door" help was available from Mercedes-Benz, and in December 1987 Mercedes' board lifted the ban on racing as the company set its sights on the DTM.
The year 1988 was a big season for AMG and Mercedes-Benz in the DTM. The 2.3-16 engine was now producing 300 bhp at 8750 rpm, and AMG's efforts resulted in four victories (of the six competing Mercedes-Benz cars) and second place in the championship behind a turbocharged Ford Sierra. For 1989, the racing engine was significantly revised by Cosworth and AMG, growing to 2.5 liters with a shorter stroke and larger bore. Called the 190E 2.5-16 Evolution I, AMG won seven DTM races with it.
In 1990, the Evolution II version of the 190E 2.5-16 appeared, and in 1991, AMG-Mercedes took the constructor's championship, while driver Klaus Ludwig took the driver's crown for AMG. Even more significant and thanks largely to the successful partnership between Mercedes-Benz and AMG in motorsport, the two companies signed an agreement where AMG products could be sold and serviced at Mercedes-Benz dealerships. By 1991, AMG was assigned the task of developing the racing version of the Evolution II and sharing the technology with other Mercedes-Benz DTM teams. The DTM was at its peak, with an audience of more than 153 million, and in 1992, AMG-Mercedes and Klaus Ludwig repeated as constructor and driver's champions. The 190E's last appearance in the DTM was in 1993, and it retired as the winner of 50 of the series championship races. AMG went on to further success with its CLK GTR, taking four racing championships in 1997 and 1998, and winning four driver's titles in the DTM beginning in 2000.
A bigger part of the businessThe 1990 dealership sales and servicing agreement between AMG and Mercedes-Benz meant big changes for the small company in Affalterbach. In 1990, a third factory opened and the workforce increased to 400. In 1993, the first co-developed vehicle, the Mercedes-Benz C36 AMG, was launched with a 280-bhp six-cylinder engine. The C36 AMG was a big success with more than 5,000 cars delivered between 1993 and 1997. In 1996, the Mercedes-Benz E50 AMG with a 347-bhp V8 was introduced and went on to sell 3,000 cars in 1996 and 1997. The 354-bhp E55 superseded the E50 in 1997 and eventually sold more than 12,000 cars. Racing was good for AMG's image, but selling road cars made money.
In 1999, AMG, the tuner that had started in an old sawmill in a backwater town in southern Germany, was purchased by DaimlerChrysler AG. The result has been a huge expansion in product offerings as AMG became Mercedes-Benz's official high-performance brand. An AMG version of nearly every product is available, including cabriolets, coupes, roadsters, sedans, and sport utility vehicles, and they are available in nearly every market in the world. Today, with more than 700 employees, AMG is responsible for all of the development processes of the more than 20,000 cars it sells yearly, including the chassis, engine and powertrain, suspension, brakes, electronics, aerodynamics and interior. In short, it starts with the shell of an existing Mercedes-Benz model, but the rest is all AMG. At the heart of every vehicle is the core of AMG's expertise: the engine.
Back where we startedAMG has proven to be adept at creating a high-performance version of nearly every one of its parent company's engines. For example, currently there is a 5.5-liter supercharged V8 engine making 517 bhp and a 6.0-liter twin-turbocharged V12 that produces 612 bhp. And there is certainly no shortage of standard production engine configurations in the Mercedes-Benz family to continue to modify. Why then did AMG feel the need to create an all-new 6.2L? Maybe if we look at some of the engine's details things will become clearer.
Longtime engine geeks (you'd be surprised at the number of them and you know who you are) will recognize the name Bernd Ramler as the man who single-handedly designed the Porsche V10 engine for the Carrera GT. Before his brief stint at Porsche, however, he was with AMG and designed the cylinder heads used with such devastating success in the DTM racing series.
When AMG decided to design an all-new engine, it hired Ramler back from Porsche to take over the development of the new all-aluminum V8 that had already been started at Affalterbach. The engine follows the modern practice of using a relatively short engine block, bolted to a rigid bedplate to which the crankshaft is bolted. The cylinder walls are coated with a new LDS process, a twin-wire arc plasma spray that ensures a low friction, long-wearing surface. A relatively small-sectioned oil pan, contoured for each vehicle application, completes the bottom end. The bore is 102.2mm and the stroke is 94.6mm, resulting in a total displacement of 6,208cc. This is a relatively large bore for a modern high-revving engine, but Ramler reckons that a 100mm bore, although not ideal for exhaust emissions, is just about perfect for motorsports usage. The short stroke means that plenty of engine speed is available, even with the large-diameter pistons, but the engine is actually limited to around 7200 rpm by the speed capability of the 7G-TRONIC seven-speed automatic transmission.
The four-valve-per-cylinder head design follows Ramler's proven configuration from the DTM racing series. The valves are at a very narrow angle, and the intake and exhaust ports are nearly vertical. Both intake and exhaust timing are continuously variable. The intake manifold is also variable and is made from magnesium. Two parallel intake flaps in the plenum increase airflow and enhance performance over the more usual single butterfly valve. Compression ratio is an extremely high 11.3:1, meaning unleaded premium is all that an AMG owner will ever buy at the pumps. The engine management system regulates fuel pressure between 3.8 and 5.0 bar (55-71 psi), depending upon power requirements and outside temperature, to provide quicker engine response.
The dual-wall stainless steel exhaust system is obviously tuned to produce a pleasing V8 rumble, but interestingly its configuration is the primary reason for horsepower differences between the various vehicles in which the new V8 is placed. In the CLK63 AMG Coupe and Cabriolet, for example, the engine makes 481 bhp at 6800 rpm. With more room under the chassis for the exhaust system, the ML63 AMG sport utility vehicle makes 510 bhp at 6800 rpm from the same engine. These numbers are outstanding, among the highest horsepower per unit of displacement of any naturally aspirated engine. AMG's new V8 also continues with the Affalterbach tradition of "one man, one engine" as each engine is completely assembled by one technician. Unfortunately, AMG has chosen to hide all of this sophistication, high technology, and craftsmanship under a tacky and flimsy plastic cover that sits atop and obscures the engine.
Back to whyNone of which actually answers the question why AMG would bother to build an all-new engine. The new 6.2-liter V8 doesn't share any parts with any other Mercedes-Benz engine family. It has a different cylinder bore than any other V8 in the Daimler-Chrysler lineup, meaning that it has to be produced on its own dedicated assembly line. The displacement of the engine is at the limits of what the block can handle, which means unless AMG resorts to supercharging or turbocharging, the engine is already near its power limit for street applications, especially with the rpm limits set by the automatic transmission.
The idea of an all-AMG designed and built engine does seem important to Europeans. This may be more important to buyers there than it is to AMG fans in the U.S.; most customers here are happy just to be able to finally get hot-rod Mercedes-Benz products. The perception in Europe is that an AMG should compete with an Aston Martin or a Porsche, not that it is simply one of the options customers have when they walk into a Mercedes-Benz dealership.
Another justification for an all-new engine from AMG might come from the company's racing heritage. If the bore of the new engine was reduced to 92mm, it would fall into the 5.0-liter category for racing and make an almost square (bore and stroke equal) engine where lighter pistons would be capable of even higher revolutions. Admittedly, 92mm would be a smaller bore than the 100mm that Herr Ramler prefers for a racing engine, but it is certainly conceivable. Another possibility that several of the AMG engineers talked about, but insisted was just an idle musing, was a 180-degree flat-crankshaft with a shorter stroke. Apparently, this too would bring the displacement near to five liters.
Who cares?Ultimately, perhaps it doesn't matter why AMG has spent so many of its resources to build its own engine. Its power and performance are impressive, regardless of the vehicle in which it's placed. With 369 lb-ft of torque available at 2000 rpm, rising to a total of 465 lb-ft at 5200 rpm, the engine pulls even the heavy ML63 AMG from zero to 62 mph in five seconds and to an electronically limited top speed of 155 mph. Does anyone actually need a sport utility vehicle that is this fast? And if so, why? The ML63 felt big and bulky on the narrow roads around Granada, Spain, but the heavy SUV had no trouble passing locals in their SEAT sedans, even uphill.
On the other hand, fast cars are a one of life's true pleasures, and the CLK63 AMG Coupe will sprint to 62 mph in 4.6 seconds and sounds like a Camaro on steroids in the process. Stiffly sprung and directly connected to the pavement, the CLK63 AMG feels like exactly what it is: a factory hot rod. Unfortunately, the coupe isn't on the menu for U.S. buyers (write to Mercedes and explain why we deserve it), and we will only get the CLK63 AMG Cabriolet, which takes an additional agonizing 0.1 seconds to reach 62 mph (in 4.7 seconds), but has commendably little cowl shake despite its open-air ambiance.
AMG has always been about engines, and that in itself is reason enough to build its own for the first time in the company's history. AMG certainly has done a first rate job. If a modified version of this engine shows up in a racing car in the not- too-distant future, the real reason for its existence will suddenly become abundantly clear.