BMW has developed a 4.0-L V8 racing engine with a maximum output of about 450 kW (600 hp). Designed specifically for U.S. regulations, the engine is intended for use in sports cars and, in modified form, to run on methanol for open-wheel competition.

"The USA is BMW's most significant market outside Germany. This indicates the importance of the project," says Karl-Heinz Kalbfell, director of BMW AG central marketing and managing director of BMW Motorsport Ltd. Aftermarket sales in the U.S. totaled 105,761 units in 1996, with BMW setting a new sales record in the U.S. in 1997. "And the fact remains," states Kalbfell, "that V8 powerplants have always been and still are the most popular and therefore the most important engines in the U.S. market. This new V8 racing engine, developed primarily for customer sport in the USA, is intended to prove our technical skill in this area, showing the public what we have to offer."

BMW's engineers have turned production engines into successful racing machines in the past. In 1995 and 1996, the BMW V12 in the McLaren BMW F1 sports car helped bring home the overall title in the BPR Sports Car Series.

BMW V8 Racing Engine Specifications

Configuration 90o cylinder angle, 98 mm (3.86 in.) cylinder spacing Valvetrain Four valves per cylinder, four overhead camshafts driven by timing chain, mechanical tappets Block Aluminum Alloy Cylinder head Aluminum alloy Capacity 3989 cm3 Ignition System Marelli transister coil Intake system 8 individual throttle cylinders Fuel-supply system One injection jet per cylinder Pistons Box-type, forged Flywheel Aluminum Clutch AP 140 mm (5.5 in) Exhaust system Fan-type manifold with flame pipes (4-2-1) Lubrication Dry sump, oil/water heat exchanger, ~ 10 L (10.6 qt.) oil capacity Oil Fina First Fuel grade RON 98 unleaded Engine control unit Marelli MR1 Approximate output 448 kW (600 hp) Approximate weight 165 kg (364 lb)

The project to develop a racing version of BMW's production V8 started in late 1996. In charge of the development process was Paul Rosche, managing director of technical development at BMW MotorÐsport Ltd. His department, which is also working on BMW's Formula 1 powerplant, was supported in the process by Heini Mader Racing Components S.A. in Switzerland. A number of changes were necessary in making the production motor a racing engine.

"The cylinder head and the crankcase have remained the same," according to Rosche. "Otherwise, we have made adjustments to the production motor to suit the race specifications." To comply with U.S. motorsport regulations, engine capacity was reduced to 4.0 L.

The racing engine uses dry-sump lubrication with oil-extraction pumps and an oil-pressure pump replaces the standard wet-sump lubrication. Rosche: "This enables us to fit the engine into the car at the lowest possible level for a good center of gravity, and the additional pumps ensure optimum extraction of oil out of the engine even under fast longitudinal and transverse acceleration." Oil is cooled by an oil/water heat exchanger.

In the interest of a low center of gravity and minimal engine length, the oil-extraction pumps—as well as the oil pump, water pump, and the alternator—are fitted at the bottom left and right next to the crankcase. As in the production engine, the four overhead camshafts are driven by a central double-roller chain. The ancillary units, in turn, are driven by gears.

While the cylinder head itself remains unchanged, valve dimensions, the diameter of the valve springs, and camshaft ignition timing were modified. Intake and outlet ducts were optimized to reduce friction losses. Instead of a conventional throttle butterfly controlling the flow of air to the cylinders, a throttle roller ensures smooth and highly efficient air intake. The big advantage is that, while a throttle butterfly is consistently exposed to the flow of air rushing by, the roller only moves into the aperture when required to slow down the flow of air, and is retracted completely under full load. The racing engine also comes with an individual intake system, with each of the eight cylinders featuring its own throttle unit. The engine's MR1 electronic ignition and fuel injection system comes from Italian supplier Magnetti Marelli.

Including ancillaries, the racing engine scales a mere 165 kg (364 lb), a reduction from the production engine of more than 69 kg (152 lb). BMW stresses that this weight reduction was made possible primarily by conventional means.

Rosche: "Since this is an engine for customers, we wanted to keep the costs involved as low as possible." The engine block is made of aluminum, as on the production unit, but the use of other, expensive, lightweight materials has been kept to a minimum. "The main approach we took in saving weight," says Rosche, "was to remove components not required in motorsport and refine a whole range of individual features."

The crankshaft is one of the components optimized for minimal weight. Its bearings have been changed and a torsional-vibration damper was being added at the front end of the crankshaft. The crankshaft itself is offset 90¡.

Following its presentation at the North American International Auto Show, the new engine was track tested and is available to interested teams for the 1999 season.