Jake vs Exhaust Brake

^ True, it's not just pumping more air to the turbo vanes/brake, it is also performing an engine braking function as I see it.

However, totally off base for the OP's topic.
OP, get a turbo brake controller for your LMM and enjoy.

4x4ord wrote:

Lynnmor wrote:
So what is this thing?

They want us to believe it is similar to a "big rig" engine brake. It is more effective than a standard exhaust brake but it is still nothing like a jake brake. If you think of an engine as an air pump you can imagine how restricting the exhaust raises the pressure at which the volume of air is being pumped at and creates more braking. Downshifting speeds the engine up which causes the engine to pump more air which also creates more braking. The Packbake holds the exhaust valve off its seat during engine braking. So with the Pac brake the piston pushes air past the slightly opened exhaust valve causing braking on the compression stroke. The pressure on the piston would be equal to the exhaust back pressure created by the restriction at the turbo. The cylinder would refill through the slightly opened exhaust valve on the power stroke and then offer the same braking as a typical exhaust brake on the exhaust stroke. Again it is the power require to force the air past the turbo that is creating the braking.

Sort of. When the valves stay closed during the compression stroke, much of the energy used to compress the air is returned to the crankshaft during the power stroke. Releasing that pressure through the exhaust on the compression stroke eliminates that.

Trixie47 wrote:
Pulling a 2012 39 ft. 5th wheel with a 2008 Chevy Silverado 3500 dwd. Question is: what is best ? Jake brake or Exhaust brake ?

I can't say what is 'best' on a Duramax. But I can attest that the factory exhaust brake on my Cummins works fantastic. I have pulled my 14,000lbs 5th wheel down a curvy, 9.5 mile long 10% grade. The OEM exhaust brake is rated at 230HP and it definitely did the job extremely well. I barely had to use the service brakes to keep my speed down and a few times had to give it throttle because the EB slowed me down too much.

KJ

Lynnmor wrote:
So what is this thing?

They want us to believe it is similar to a "big rig" engine brake. It is more effective than a standard exhaust brake but it is still nothing like a jake brake. If you think of an engine as an air pump you can imagine how restricting the exhaust raises the pressure at which the volume of air is being pumped at and creates more braking. Downshifting speeds the engine up which causes the engine to pump more air which also creates more braking. The Packbake holds the exhaust valve off its seat during engine braking. So with the Pac brake the piston pushes air past the slightly opened exhaust valve causing braking on the compression stroke. The pressure on the piston would be equal to the exhaust back pressure created by the restriction at the turbo. The cylinder would refill through the slightly opened exhaust valve on the power stroke and then offer the same braking as a typical exhaust brake on the exhaust stroke. Again it is the power require to force the air past the turbo that is creating the braking.

A Jake brake uses a camshaft or hydraulic pressure to pop the exhaust valve open near top dead centre on the compression stroke preventing the energy in that compressed air from pushing down on the piston during the power stroke. The pressure on the top of the piston during the compression stroke is used to accomplish the engine braking and is much higher than the 60 psi or so that a PacBrake or typical exhaust brake utilize for braking.

The Pacbrake LoadLeash holds the exhaust valve open on the compression stroke, allowing the exhaust brake to work on both the exhaust and compression strokes and eliminating the rebound effect of the power stroke. Only for the 6.7 Cummins though.

So what is this thing?

rhagfo wrote:

ACZL wrote:
Would take a heck of a lot of modding to stuff a engine that uses a Jake brake in a pick up. If I'm not mistaken, I think Cummins invented the Jake Brake and granted it's use for all semi engines but some mfr's may offer their own version of a Jake to which (IMO) aren't as good. A true Jake requires the engine to be between 1600-2000 to get the best retarding power. Exhaust brakes offered by Ford, GM & Ram are better than nothing and from what I gather, folks seem to be quite happy w/ them.

Not so, PacBrake makes an engine brake for the Cummins 6.7 that is a bolt on kit. Looks like it raises the valve cover about 1-1/2”.

The PacBrake exhaust brake is not a compression release brake such as a "Jake Brake". It is a little more effective than a standard exhaust brake but both the PacBrake and a standard exhaust brake utilize the turbo vanes to create back pressure in the exhaust system to provide the engine braking. The engine brakes on the bigger diesels are far more effective. A pick up truck doesn't really have need for the level of braking provided by a "Jake".

ACZL wrote:
Would take a heck of a lot of modding to stuff a engine that uses a Jake brake in a pick up. If I'm not mistaken, I think Cummins invented the Jake Brake and granted it's use for all semi engines but some mfr's may offer their own version of a Jake to which (IMO) aren't as good. A true Jake requires the engine to be between 1600-2000 to get the best retarding power. Exhaust brakes offered by Ford, GM & Ram are better than nothing and from what I gather, folks seem to be quite happy w/ them.

Not so, PacBrake makes an engine brake for the Cummins 6.7 that is a bolt on kit. Looks like it raises the valve cover about 1-1/2”.

ktmrfs wrote:

ACZL wrote:
Would take a heck of a lot of modding to stuff a engine that uses a Jake brake in a pick up. If I'm not mistaken, I think Cummins invented the Jake Brake and granted it's use for all semi engines but some mfr's may offer their own version of a Jakeibetween 1600-2000 to get the best retarding power. Exhaust brakes offered by Ford, GM & Ram are better than nothing and from what I gather, folks seem to be quite happy w/ them.

Clessie Cummins, one of the founders of what became Cummins engine is credited with the invention of the jake brake in the late 50's. It was granted a patent in the early 60's. I think by that time he was not associated with Cummins and when he went looking for someone to market it, Jacobs mfg was the only taker, which, relates to how it got it's name, Jake brake. Jacobs started mfg it in about 1961 IIRC. BTW it's the same Jacobs that makes 3 jaw drill chucks.

It's hard to believe something more efficient such as electric motors and batteries haven't replaced it yet.

ACZL wrote:
Would take a heck of a lot of modding to stuff a engine that uses a Jake brake in a pick up. If I'm not mistaken, I think Cummins invented the Jake Brake and granted it's use for all semi engines but some mfr's may offer their own version of a Jakeibetween 1600-2000 to get the best retarding power. Exhaust brakes offered by Ford, GM & Ram are better than nothing and from what I gather, folks seem to be quite happy w/ them.

Clessie Cummins, one of the founders of what became Cummins engine is credited with the invention of the jake brake in the late 50's. It was granted a patent in the early 60's. I think by that time he was not associated with Cummins and when he went looking for someone to market it, Jacobs mfg was the only taker, which, relates to how it got it's name, Jake brake. Jacobs started mfg it in about 1961 IIRC. BTW it's the same Jacobs that makes 3 jaw drill chucks.