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
I tried out the compression release brake (Jake Brake) on our Kenworth today. I had no trailer hooked up and only a small load on its back. Gross weight of about 63000 lbs. On level ground it slowed from 100 km/h to 80 km/hr in 8.5 seconds. The boost pressure during braking was at about 30 psi. Engine rpm at 100 kph was 2000 rpm. This works out to a retarding horsepower of 626 hp. So the difference between a compression release brake and an exhaust brake is pretty huge.
Edit: I should have mentioned that shifting the transmission into neutral and letting the truck coast resulted in the unit slowing from 95 kph to 85 kph in 28.3 seconds which equates to 94 reverse HP coming from rolling resistance and drag.
So the engine brake on the Cummins in the Kenworth can generate 626 - 94 or 532 reverse HP.
Compared to the Powerstroke's ability to generate 141 reverse HP (186 - 45)
Edit: I should have mentioned that shifting the transmission into neutral and letting the truck coast resulted in the unit slowing from 95 kph to 85 kph in 28.3 seconds which equates to 94 reverse HP coming from rolling resistance and drag.
So the engine brake on the Cummins in the Kenworth can generate 626 - 94 or 532 reverse HP.
Compared to the Powerstroke's ability to generate 141 reverse HP (186 - 45)
