Got Diesel? by Anthony Komarek

Why hasn't the diesel engine caught on in the U.S.? The modern diesel engine has made tremendous progress towards becoming accepted in the US market with the use of ultra-high injection pressures, pilot injection, and turbo charging. Diesel engines are no longer noisy, smelly, and slow the Mercedes Benz E320 CDI is a perfect example of a diesel passenger car that is quiet, very fuel efficient, and lots of fun to drive. And now biodiesel seems to be a real alternative (as you will see in a future contribution).

At the 2005 SAE Noise and Vibration Conference in Traverse City, MI, engineers at Ricardo UK Ltd. and Ricardo Inc. presented several papers on achieving diesel appeal in the U.S. In their paper Achieving Diesel Vehicle Appeal Part 1: Vehicle NVH Perspective, (2005-01-2484) key diesel vehicle NVH issues were identified and discussed. Some of the noise concerns addressed were combustion noise, idle noise and vibration, start-up and shut-down shake, and air intake and exhaust noise. The paper also discusses the application of numerous NVH methodologies to support the NVH development process. Using the techniques described in these papers it is possible to produce highly appealing diesel products that will be successful in the U.S. automotive market.

One very good example of a highly appealing vehicle, and personal favorite of mine, is the new Mercedes Benz E320 CDI. The E320 CDI is powered by a 3.2L DOHC 24-valve inline-6 engine that generates 201 hp and 369 lb-ft of torque. The gasoline model has a 3.2L SOHC 18-valve V-6 engine with 221 hp and 232 lb-ft of torque. The performance and fuel economy figures are what really makes the CDI model impressive. The 0-60 mph time of the gasoline model is 7.1 seconds and the diesel model reaches 60 mph in a stout 6.6 seconds. The EPA fuel mileage estimations (city/hwy) are 19/27 mpg for the gasoline model and 27/37 mpg for the diesel. From a NVH standpoint, special attention was given to the reduction of the engine combustion noise, and this was achieved by utilizing a very high pressure (23,000 psi) common rail injection system with dual-pilot injections. My hope is to be able to report on a test drive of the E320 in the near future.