No more diesel knock

If you haven't driven any diesel-powered cars lately, you probably remember them as loud, smelly, and hard to start in sub-freezing temperatures. In the early 1980s, a neighbor of mine in Minneapolis was crazy enough to buy one. Talk about an opportunity to do some cold weather testing!

Well, times have changed. On a recent visit to Robert Bosch's new test track in Boxberg, Germany, I had a chance to drive a diesel-powered 1998 Chrysler Voyager SE, equipped with Bosch's VP36 direct fuel injection system. While not the minivan type, I have to admit I was pleasantly surprised by the exceptionally quiet ride.

When people talk about diesel "knock," they are referring to the combustion noise, which is an unwelcome consequence of the high rise in pressure during rapid combustion. Direct fuel injection systems help to reduce this noise by timing the injection so that it occurs closer to the end of the compression stroke.

Taking the minivan out for a few loops on the high speed oval was sufficient to prove out the effectiveness of Bosch's technology. While traveling at speeds approaching 90 mph, I was actually able to carry on a conversation in a normal speaking voice with a Bosch engineer who was along for the ride. And in a moment of sheer ludicrousness out on the test track, I had no difficulty taking a long-distance call that came in for me on a cell phone.