Auburn Hills, MI--As the trend toward lighter-weight more energy-efficient vehicle designs continues, materials will play an increasingly critical role. The new power train for the 1999 Jeep Grand Cherokee is a good example.
Chrysler's newest sport utility vehicle (SUV) is larger than its earlier models, but gets 8% more mpg on average, while reducing emissions some 30%. Behind these noteworthy statistics lies the Cherokee's new 4.7(liter) V8 engine's automatic 5-speed 45RFE fully electronic automatic transmission and transfer case. In addition to the lower fuel and emissions figures, the power train weighs 50 lb less than its predecessor, according to Mike Kirk, Jeep power train project manager.
How did this come about? Kirk reports that the results stem from the use of a potpourri of advanced materials. They include: aluminum cylinder heads and an all-aluminum front cover; powder-forged connecting rods; intake manifold made of 35% glass-filled nylon 66 molded with the lost-core process; magnesium cam covers for less weight, more strength, and less space compared to aluminum designs; and an "industry first" compacted graphite-iron bedplate for more robustness during foundry and machining operations.
Chrysler believes that the $2.6 billion spent on the Grand Cherokee design is worth it. Why? Because predicted annual demand for SUVs will grow to 3.3 million by 2005. That's up from 2.4 million in 1997 and an estimated 2.7 million for the 1999 model year.