Downshift or exhaust brake?
I was just thinking after reading a post about gas vs diesel trucks where somebody mentioned they liked diesel because of the exhaust brake. I've never had a diesel, always gas. If I come up to a long...
Forum Discussion
Turtle n Peeps wrote:
The reason an exhaust brake works better on a diesel is because of the compression ratio. It takes a lot more energy to compress an 18 to 1 cylinder with air in it than a 10 to 1 cylinder with air in it.
The high compression ratio of a diesel contributes much to engine braking when a "Jake Brake" is used because the exhaust valve is opened at the top of the compression cycle. With these little pick ups and the exhaust brakes they have the compressed air is allowed to push the piston down on the powerstroke there by largely offsetting any braking that was accomplished on the compression stroke. The one thing that does make the diesel more effective at engine braking is the fact that the turbo is pushing more air through the engine than with a naturally aspirated engine. On the other hand the higher revving gasoline engine can pump more air than the diesel because it is comfortable revving higher.
