Posted by RDavis on Sunday, February 01, 2004 at 4:50PM :
In Reply to: Dumb diesel question for the experts posted by Stan on Sunday, February 01, 2004 at 4:20PM :
Stan, I'm no expert by a long shot but I do know a few things about diesels vs gassers.
The gas eng. operates at a lower compression because its ignition is caused by a spark. The diesel operates at a much higher compression because it must compress the air intake charge soo much that it heats the air enough to ignite the fuel when it is injected
so, the diesel eng must withstand higher compression and torque and is usually more expensive to rebuild and is designed for longevity (200,000-300,000 mi.)
There are the low rpm and higher rpm diesels.
Both are usually lower operating rpm s than a gas eng. which requires higher differetial gears for hiway use using the tranny gearing for accerating to top speed . The high torque of the diesel can easily overcome the higher gearing. Lower geared rearends tend to cause a diesel to turn excessive rpms hence that is why gas eng. use lower gears in the rearends. If I'm incorrect, someone can correct any misinfo I've given.