Community Forums

kengardner · 01-26-2022, 01:07 PM

I'm still shopping for a DP and need some honest opinions on Exhaust brake vs Engine brake for a lot of mountain driving pulling a new Jeep Wrangler. I have searched and am not finding anything. I'm trying to decide between an older 40-45 foot, 400 + hp which will have an engine brake and a newer and shorter 36-38 foot which will have an exhaust brake since almost all have a 340-360 hp engine. I have driven a 34 foot gasser pulling a jeep and it was touch and go in the steep mountain areas even starting out very slow and trying to stay in lower gears. The 10 cyl Ford engine would really get to high rpms and I would jab the brakes hard to drop the rpms and in only a short distance was right up there again. The wife would not drive in those areas and did not really even want to be a passenger. Can I expect the smaller DP with an exhaust brake to slow the DP down better than the gasser with tow / haul and gearing ??? A few of the trouble spots were I-70 west of Denver, I-75 west of Chattanooga, and I-81 or 77 ?? near the Shenandoah Valley. At all of those places and a few others the cool down areas were busy and I also needed to stop for a while to cool down and remove my wife's finger nails from my arm ! We would both rather have a shorter DP to enable us to fit into more state / national parks but do not want to white knuckle to get there. Please give me some opinions. I found several posts a while back but can't locate them now. Ken

Busskipper · 01-26-2022, 01:15 PM

Both work - get the floorpan that works for YOU!

JMHO,

Old-Biscuit · 01-26-2022, 01:21 PM

Simple explanation 'Engine Brake' is the engine is turned into an air compressor. Using the drive train to power it as truck slows.
*Modified Cylinder Head

An 'Exhaust Brake' blocks the exhaust from exiting out of engine. This cause back pressure and slows the truck down.
*Inline on exhaust after turbo down pipe

Both systems use the transmission and drive train in a lower gear to increase rpm. More rpm more stopping power.

Engine Brakes are Nosier......Exhaust Brakes are quieter
BOTH slow down the rig w/o using service brakes

2cyber71 · 01-26-2022, 01:28 PM

Both work fine
I would suggest look for the RV you can afford.
Power and torque are more important in mountains than if it has a exhaust or engine brake
Lower HP diesels have the exhaust and higher HP diesel have the engine brake.
Mountain driving requires good torque, and many low end diesels are underpowered.

Max Headroom · 01-26-2022, 01:29 PM

Being a guy that lives in the area and has to do the I-70 (Vail, Eisenhower, Genese, 8 mile grade in UT, etc) lot, I'd go with the longer wheelbase and the real Jake every time.
The real Jake will hold the coach back no problem. Sometimes it's too strong, and I have to set it at half instead of full. Plus people with pac/exhaust brakes seem to post a lot about lack of function issues, and they require their own maintenance. I say the Jake wins hands down every time.
Floorplan doesn't mean squat if there are roads you're afraid to travel on.
In the end, most RV have such similar floorplans, it really does come down to drive train for a lot of us.

wolfe10 · 01-26-2022, 01:30 PM

Yes the engine compression brake gives more braking HP than an exhaust brake. Either can successfully be driven most anywhere. Have had two with exhaust brakes and one with an engine compression brake. All with Allison 6 speed 3000 series transmissions. Quarter million miles total all over Canada, U.S. and Mexico including some outrageous mountains in Mexico.

In addition to older large displacement diesels, the Cummins ISL (8.9 liter) could be ordered with an engine compression brake. Our 2003 Alpine had exactly that combination. Check, because the ISL could also be ordered (less $$) with an exhaust brake.

kengardner · 01-26-2022, 03:02 PM

Thanks for the replies, With your input I am now leaning towards an older 45' Newmar Essex and it has lots of power and torque and a Jake brake and checks ALL of our boxes so it should do just fine. I'll just have to hunt a little harder for the camping spots ! Ken

Dav L · 01-26-2022, 07:57 PM

I had my RV loaded down to capacity with tools / parts and dragging my car trailer with 5300lb car that was also filled. I didn't need to touch the air brakes once on the downside of Vail Pass (Rockies). Just used the engine braking. Just alternated between 1/2 and off the whole way down. Start slow, remain slow. Enjoy the view.
One of the first good memories of the new to me RV.
Worked so nice, I put an electric foot switch on the On / Off engine braking which allows hands on wheel.

No comparison to my F53 Bounder.

bhammond1980 · 01-26-2022, 08:00 PM

I've had both. In our last coach we had a c7 cat, Allison 6 speed with exhaust brake. In my opinion it worked but just barely. I was on the brakes constantly in a decent otherwise the coach would run away. It worked best with the engine revving near red line.
Our second coach has a Detroit 60 series with a ZF 12 speed auto shift and a true multi-stage engine brake. In the high setting the engine brake will stop the coach without touching the brakes. It is engineered to slow an 80,000 semi so in a 56,000 lb RV it's very effective.

Mile Marker 42 · 01-26-2022, 08:05 PM

Exhaust brake owner here. It does well if you truly understand how to maximize it's use, which I do. However, if we ever upgrade our coach, 1 of my many must have requirements is a real Jake brake.

bpu699 · 01-27-2022, 06:50 AM

Quote:

Originally Posted by Mile Marker 42

Exhaust brake owner here. It does well if you truly understand how to maximize it's use, which I do. However, if we ever upgrade our coach, 1 of my many must have requirements is a real Jake brake.

How does one "maximize" its use? My exhaust brake seems to work just fine, but it is alarming that it sometimes allows very high rpm to do its job. When it first kicks in the RPM needle zings to the right...

Is there a max speed at which to engage it?

Any other tips?

wolfe10 · 01-27-2022, 07:08 AM

Quote:

Originally Posted by bpu699

How does one "maximize" its use? My exhaust brake seems to work just fine, but it is alarming that it sometimes allows very high rpm to do its job. When it first kicks in the RPM needle zings to the right...

Is there a max speed at which to engage it?

Any other tips?

First, all exhaust brakes are not the same. The PacBrake PRXB, for example generates more braking HP at lower RPM (same at higher RPM) as most other exhaust brakes.

And, yes, to maximize braking HP requires higher engine RPM.

Please note that your engine has TWO different RPM limits:
Governed RPM= max RPM while working/under load
Max permissible RPM under no load, i.e. with exhaust brake on.

Call your engine manufacturer with your engine serial number and ask for these numbers for your engine.

Basics for going down long grades is to select a GEAR (use transmission down arrow) and SPEED where your speed is in EQUILIBRIUM-- you are neither speeding up nor slowing down. Physics dictates that this speed in our motorhome will be faster than a loaded 18 wheeler on the same grade and slower than an empty one. This speed has nothing to do with the speed limit. It could be 30 MPH on a dead straight road with 6% downgrade.

dizcom · 01-27-2022, 07:42 AM

I wouldn't let the brake be the deciding factor in your purchase. Get the coach you like and spend some time getting to know it. There's more than just either/or. An engine brake can be added to a lot of engines if it doesn't have one already, and they can be changed to give you more braking if you want it. Do some research on the engines if it really bugs you, but I think you'll find that it won't matter once you're underway.

Crasher · 01-27-2022, 11:18 AM

I like many have had both the exhaust brake and the Jake type compression brake. If I were to rate their effectiveness on a scale of 1 to 10 with 10 being the highest in stopping power, the EB would be a 4. The CB would be a 5 in low and a 10 in high. Yes, the EB can be a nice aid at higher rpm, but it can't compare to what the compression brake can do in high position. By all means, the floor plan is the most important to consider, but keep in mind the braking differences in mountain driving. The only time I almost lost it on a mountain grade was coming down the east side of Teton pass 10% grade. My trailer brakes failed and I was barely able to get it stopped. The exhaust brake wasn't enough to control speed. It would have been a non-event with a compression brake.