Half ton towable fifth wheels? OR NOT

[mike.t]

Originally Posted by timfromma

If I'm on a downhill, I will manually activate my trailer brakes as means of speed control.

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The way I see it if you have a 1/2 ton gasser you are already towing a light weight trailer (unless someone told you different) you don't need to manually activate your trailer brakes ( it really wears them out fast your also stopping your TV) unless you are going to fast or in terrain where you should not be over weight. I suggest the exhaust brake

[OldCoot]

Originally Posted by mike.t

The way I see it if you have a 1/2 ton gasser... I suggest the exhaust brake

Something new to me, an exhaust brake on a gas engine?????? Don't think a gas engine has enough compression for it.

[KingFisher]

Originally Posted by OldCoot

Something new to me, an exhaust brake on a gas engine?????? Don't think a gas engine has enough compression for it.

I have engine braking on my 2015 silverado gasser, not sure how it works but it works.

[mike.t]

Originally Posted by OldCoot

Something new to me, an exhaust brake on a gas engine?????? Don't think a gas engine has enough compression for it.

That was a little humor regarding gas and diesel engines. No need to be you didn't get it.

[BandJCarm]

Comment about 'engine braking' from a non-gearhead that might be off base.

On my Duramax, I believe, but am not sure, that the "exhaust brake" is not an "engine brake". I also might be wrong but I think on the Rams, it is a true engine (jake) brake.

I believe that my exhaust brake button, when engaged, merely causes an even more aggressive downshifting of the transmission than the Tow Haul mode (which does same thing) would do if it was engaged alone. It's more of an "aggressive transmission downshifter" than a true Jake Brake.

Again, not my baliwick, but that's what I understand and it's how I use it.

[D_B Travelers]

Jake brake vs. Exhaust brake. After a bit of research I believe the main difference is in how the exhaust valves function. In the Jake (or Jacob's) brake, the exhaust valves are opened releasing the compression to the engine and thus slowing the motor. On an exhaust brake the exhaust valves are kept closed, therefore preventing the gasses from escaping through the exhaust. The back pressure causes the engine to slow. I believe my Allison has the latter type, which works great in conjunction with manually shifting down for steep grades.

[OldCoot]

Originally Posted by D_B Travelers

Jake brake vs. Exhaust brake. After a bit of research I believe the main difference is in how the exhaust valves function. In the Jake (or Jacob's) brake, the exhaust valves are opened releasing the compression to the engine and thus slowing the motor. On an exhaust brake the exhaust valves are kept closed, therefore preventing the gasses from escaping through the exhaust. The back pressure causes the engine to slow. I believe my Allison has the latter type, which works great in conjunction with manually shifting down for steep grades.

I agree, but neither are available, to my knowledge, on a gas engine, it has to be done with the transmission. It has been my experience that using the transmission to downshift for braking repeatedly will only accelerate the use of oil blow by. JM experience from years of playing with engines to hear the glaspac mufflers and make them backfire.

[Cowracer]

Originally Posted by OldCoot

I agree, but neither are available, to my knowledge, on a gas engine, it has to be done with the transmission. It has been my experience that using the transmission to downshift for braking repeatedly will only accelerate the use of oil by blow by. JM experience from years of playing with engines to hear the glaspac mufflers and make them backfire.

Any engine is basically an air pump. If you block off the exhaust (which is what an exhaust brake does) the engine turns into an air compressor. Air can get in, it cannot get out, and it takes energy to compress air. Any engine will function like that with the exhaust blocked (or partially blocked) off.

A Jacobs "jake" brake opens the exhaust valve at the time the injector or spark plug would normally fire. Energy is used up in the compression of the air in the cylinder. Its basically the same function as an exhaust brake, but the action occurs at a different place in the engine.

With all that being said, exhaust brakes (of any kind) are most effective on diesel engines because they do not have throttles. They gulp in the same amount of air no matter how far you press the accelerator. Gassers usually have the throttle closed for deceleration, largely limiting the amount of air that can be compressed to aid deceleration.

What some new computer controlled gassers with throttle by wire are doing is killing the ignition spark and fuel injection pulse, and opening the throttle WFO while in "exhaust brake" mode. In that case, they can be just as effective as one on a diesel.

Tim

[KingFisher]

Originally Posted by BandJCarm

Comment about 'engine braking' from a non-gearhead that might be off base.

On my Duramax, I believe, but am not sure, that the "exhaust brake" is not an "engine brake". I also might be wrong but I think on the Rams, it is a true engine (jake) brake.

I believe that my exhaust brake button, when engaged, merely causes an even more aggressive downshifting of the transmission than the Tow Haul mode (which does same thing) would do if it was engaged alone. It's more of an "aggressive transmission downshifter" than a true Jake Brake.

Again, not my baliwick, but that's what I understand and it's how I use it.

This is how I understand it. The Duramax exhaust brake works off of the turbo vanes. In tow/haul it is also helped by transmission downshifting.

On my silverado gas I believe the engine brake in tow/haul is purely a transmission function that works automatically so I don't have to downshift it myself.

[wicked1]

My 2016 F350 Power Stroke has an Exhaust Brake, works well when towing but don't use it when not towing so not sure if it even works when not towing


2016 F350 CREW 6.7 PowerStroke Diesel
2015 FR Rockwood Roo 23IKSS

[OldCoot]

Originally Posted by Cowracer

Any engine is basically an air pump. If you block off the exhaust (which is what an exhaust brake does) the engine turns into an air compressor. Air can get in, it cannot get out, and it takes energy to compress air. Any engine will function like that with the exhaust blocked (or partially blocked) off.

A Jacobs "jake" brake opens the exhaust valve at the time the injector or spark plug would normally fire. Energy is used up in the compression of the air in the cylinder. Its basically the same function as an exhaust brake, but the action occurs at a different place in the engine.

With all that being said, exhaust brakes (of any kind) are most effective on diesel engines because they do not have throttles. They gulp in the same amount of air no matter how far you press the accelerator. Gassers usually have the throttle closed for deceleration, largely limiting the amount of air that can be compressed to aid deceleration.

What some new computer controlled gassers with throttle by wire are doing is killing the ignition spark and fuel injection pulse, and opening the throttle WFO while in "exhaust brake" mode. In that case, they can be just as effective as one on a diesel.

Tim

Fully aware of how exhaust brakes work, they just don't put them on gas engines due to the fact that the compression is too low to be effective. Been a gearhead all my life.

[mike.t]

On racing motorcycles years back it was called a compression release. Jacobs had a law suit against towns that had posted signs that said do not use/engauge jake brakes in town because they were not all Jake brake by design.

[B and B]

Originally Posted by Time-Travelers

We don't have that weight yet, still 'making it ours'. Should be close to 'fully' equipped and weighed by the end of the month. Dry weight of our 8289WS is 8125 with a CC 1208.

Flat towing no problem when i did it with F 150 but over weight from day 1! Trailer brakes ran pretty high to slow it.