Downshift or exhaust brake?

Cummins12V98 wrote:
I don’t think our Cummins will wind up to 3,500 rpm.

Not stock. Tuned, that is a different story. The marine version of the 6.7L will wind up that high but it does not have the same emission regulations..

I don’t think our Cummins will wind up to 3,500 rpm.

Finally got around to making a video following my brother down a back country road. The data is in the middle circle. Top number is VGT vane position, middle is boost, and bottom is turbo shaft speed. Sorry it is so shaky. The road we were on was a bumpy one.

The EB is on when the VGT position is about 97%. Boost goes to zero and shaft speed decreases.

Cummins exhaust brake

4x4ord wrote:

Me Again wrote:
Well this morning on the way to the RC field I tried and tried to see boost on the exhaust brake.

Finally I hit a down hill exit ramp at 70 MPH in 4th gear and saw boost come up the the claimed 5-7 PSI range for a second or two. Braking did not change when this happen. We will not be towing until May 1st. Chris

My truck is not around right now otherwise I would try the Ford but if you're willing to screw around this would quantify what your exhaust brake is truly doing:

Rev your truck to 3500 rpm while locked in 3rd gear then back off the throttle and using a stop watch measure the time it takes for the engine to slow from 3200 rpm to 2700 on level ground with the exhaust brake on and then measure again with the exhaust brake off. The negative horsepower produced by the exhaust brake could be calculated from this information.







;

My truck has very seldom seen 3000 RPM if ever and I have no intention of ever rev'ing it to 3500. I know what the exhaust brake does and I have towed at 24,500 twice to Arizona and back, once around 21,000 with the old trailer. I know that I would not be able to go down cabbage patch I-84 East of Pentleton in Oregon with the exhaust off and in just Tow Haul without over working the service and trailer brakes.

I have a better plan, you come down and run your fully loaded 5th and truck down Cabbage Patch without your exhaust brake. Then report back how you liked the trip down that hill. Chris

IdaD wrote:

4x4ord wrote:

Grit dog wrote:
While I’ll likely not tow heavy enough to make great use of a compression brake, the Load Leash is just another example of how awesome a time we’re living in for vehicles.
I mean having a pickup truck with exhaust brake and a real Jake brake? Pure awesomeness!

The LoadLeash sounds like a step up from an exhaust brake on its own but still quite a step down from a "real Jake brake" in my opinion. I wonder how long it will be till we see the energy used in braking stored as compressed air or in batteries to be used to climb the next hill.

I think the new light hybrid Ram (I forget what they call it) has regenerative braking.

Yet another cool means of slowing a vehicle sans service brakes.
4x4ord, how is a load leash a step down from a Jake? I'm no big diesel truck expert, but are they not both mechanical compression brakes?
On a side note, I wonder when we may see hydraulic retarders enter the heavy (light duty trucks) pickup market either engine or trans? Especially trans retarders. With today's bulletproof and computer controlled transmissions, I bet the components are almost all already in place for this.

Me Again wrote:
Well this morning on the way to the RC field I tried and tried to see boost on the exhaust brake.

Finally I hit a down hill exit ramp at 70 MPH in 4th gear and saw boost come up the the claimed 5-7 PSI range for a second or two. Braking did not change when this happen. We will not be towing until May 1st. Chris

My truck is not around right now otherwise I would try the Ford but if you're willing to screw around this would quantify what your exhaust brake is truly doing:

Rev your truck to 3500 rpm while locked in 3rd gear then back off the throttle and using a stop watch measure the time it takes for the engine to slow from 3200 rpm to 2700 on level ground with the exhaust brake on and then measure again with the exhaust brake off. The negative horsepower produced by the exhaust brake could be calculated from this information.







;

Well this morning on the way to the RC field I tried and tried to see boost on the exhaust brake.

Finally I hit a down hill exit ramp at 70 MPH in 4th gear and saw boost come up the the claimed 5-7 PSI range for a second or two. Braking did not change when this happen. We will not be towing until May 1st. Chris

4x4ord wrote:

Grit dog wrote:
While I’ll likely not tow heavy enough to make great use of a compression brake, the Load Leash is just another example of how awesome a time we’re living in for vehicles.
I mean having a pickup truck with exhaust brake and a real Jake brake? Pure awesomeness!

The LoadLeash sounds like a step up from an exhaust brake on its own but still quite a step down from a "real Jake brake" in my opinion. I wonder how long it will be till we see the energy used in braking stored as compressed air or in batteries to be used to climb the next hill.

I think the new light hybrid Ram (I forget what they call it) has regenerative braking.

Grit dog wrote:
While I’ll likely not tow heavy enough to make great use of a compression brake, the Load Leash is just another example of how awesome a time we’re living in for vehicles.
I mean having a pickup truck with exhaust brake and a real Jake brake? Pure awesomeness!

The LoadLeash sounds like a step up from an exhaust brake on its own but still quite a step down from a "real Jake brake" in my opinion. I wonder how long it will be till we see the energy used in braking stored as compressed air or in batteries to be used to climb the next hill.

While I’ll likely not tow heavy enough to make great use of a compression brake, the Load Leash is just another example of how awesome a time we’re living in for vehicles.
I mean having a pickup truck with exhaust brake and a real Jake brake? Pure awesomeness!