Federal-Mogul Boosts Performance for Aluminum Diesel Pistons

A new production process is helping Federal-Mogul Corp. make aluminum pistons with the strength and thermal performance to work in exceptionally powerful diesel engines.

The technology debuted in March in BMW AG's new triple-turbo 3.0-liter diesel, which makes a record 124 hp per liter of displacement. Federal-Mogul says previous piston designs have difficulty handling power levels greater than about 120 hp/liter.

The engine, which marks BMW's first use of a diesel for its "M" performance models, produces 381 hp and 546 lb-ft of torque. BMW says the engine can propel the vehicles from zero to 62 mph in 4.7 seconds. The powerplant is being rolled out this year in Europe in M editions of the 5 Series sedan and wagon and X5 and X6 crossover models.

Key to Federal-Mogul's new piston design is the company's "Durabowl" process, which re-melts the aluminum alloy around the rim of the piston's combustion bowl. The process modifies the aluminum's microstructure and boosts the strength of the rim to withstand higher mechanical and thermal loads.

The Durabowl pistons also feature a raised cooling gallery, which circles the interior of the piston head. The new configuration places cooling oil nearer the piston bowl than was possible in previous designs. The result is cooler piston temperatures, which reduce internal friction and improve durability. Federal-Mogul says the enhanced design required "major" advances in the precision and reliability of the piston casing process.

The company also developed a new two-dimensional ultrasonic inspection technique to help control quality. Federal-Mogul says traditional one-dimensional ultrasonic testing can detect defects but not their size or position. The company says its 2-D process can collect 125,000 data points in 30 seconds to pinpoint any flaws.

The new piston design, molding process and inspection technique were developed at Federal-Mogul's tech center in Nuremberg, Germany.