Engine Brake

[Vegasguzzi]

Hello all. I am new to the RV experience at the class A level. I have narrowed my search to two coaches. One has an engine brake and one does not. The one coach is a 350 cummins w/o an engine brake. How important is this option?

[Mike Canter]

It needs some type of auxiliary brake. Either was is called an exhaust brake which is made by Pacbrake Diesel Exhaust Brakes and Retarders | Duramax, Cummins Turbo Diesel, Powerstroke Brakes or Jacobs Jacobs Vehicle Systems - Light Duty Exhaust Brake or a engine compression brake on the motor which is called a Jake Brake or a compression brake or an engine brake Jacobs Vehicle Systems - How the Jake Brake Works. Unless the MH is super big and heavy the exhaust brake works just fine and will get you down any steep grade without overheating your regular brakes which are called service brakes. The motorhome should have one of these type systems. It is possible to install a exhaust brake such as the Pacbrake of the motorhome if it doesn't have a one and you really like the motorhome. Normally an installation of the exhaust brake also requires reprogramming the Allison transmission and that is not a big thing but has to be done.

[Tha_Rooster]

Drum brakes heat up and fail quicker than disc. That's why a exhaust brake is a big help mine will hold it back on a 6% grade with little brake help.

[GaryKD]

Hi Vegasguzzi,
Welcome to iRV2. I would not drive a diesel powered coach without an engine assisted brake (like one of the products mentioned in Mike Canter's post). This feature is vital to the safety of everyone.

[maint1]

I'm guessing you are from Las Vegas as am I. In this area you will probably be doing a lot of mountain driving. In this part of the country I use my exhaust brake all the time when I am going through the mountains. I have drum brakes and in emergency situations or when I am towing and going down hill, the drum brakes heat up and fade very quickly. If you go with the coach without the brake, get one installed.

[Pusherman]

Originally Posted by Mike Canter

It needs some type of auxiliary brake. Either was is called an exhaust brake which is made by Pacbrake Diesel Exhaust Brakes and Retarders | Duramax, Cummins Turbo Diesel, Powerstroke Brakes or Jacobs Jacobs Vehicle Systems - Light Duty Exhaust Brake or a engine compression brake on the motor which is called a Jake Brake or a compression brake or an engine brake Jacobs Vehicle Systems - How the Jake Brake Works. Unless the MH is super big and heavy the exhaust brake works just fine and will get you down any steep grade without overheating your regular brakes which are called service brakes. The motorhome should have one of these type systems. It is possible to install a exhaust brake such as the Pacbrake of the motorhome if it doesn't have a one and you really like the motorhome. Normally an installation of the exhaust brake also requires reprogramming the Allison transmission and that is not a big thing but has to be done.

Mike is absolutely correct.

I would definitely want an auxiliary exhaust/engine brake (and do) on my coach.

[Vegasguzzi]

Thanks for the advice. I was looking at a 2008 Ventana and was a little surprised to learn that there was not an exhaust brake. I live in the southwest and I will be in some mountains pulling a Jeep and from what I have learned to date felt this was an important option. Thanks for confirming my suspicions. I guess I am leaning toward the Discovery

[J Walker]

It is possible that the Ventana doesn't have an exhaust brake with the new Cummins ISB engines. If so the ISB has a variable turbo intake which is equivalent to an exhaust brake. This is a relatively new feature and I don't have the experience to compare it with an exhaust brake. I would not rule the Ventana out and a little research is in order. You can get a brochure on the Ventana here Ventana LE Motorhome > Standard Features | Newmar RV
I would also call Cummins to get more info on the variable turbo stopping power compared with an exhaust brake, 888 769 3778.

[Vegasguzzi]

Jim Thanks

I have been doing a little research and it looks like the Ventana automatically varies turbo flow. I will call the Cummins dealer and ask a couple more questions. You have further complicated my decision. I am looking at an 07 Discovery and an 08 Ventana. I like both floorplans, noe I just need to take the plunge.

[Mike Canter]

Jim is 100% correct. I just read up on the motor and it has an integral exhaust brake that works off the new design VG turbo. This is what Cummins says......

The Holset Variable Geometry Turbocharger (VG Turbo)
provides exhaust braking without additional add-on
hardware in the exhaust system and eliminates exhaust
brake maintenance. The operator activates braking by
using the brake switch in the driver’s compartment. ISB
exhaust braking assists in stopping the motorhome while

reducing wear on the service brakes.


Check on page four of the Cummins engine data
http://cumminsengines.com/assets/pdf/4971103.pdf

[Luckiest Dreamer]

I drove over 1 million miles pulling two trailers. The company I worked for refused to install engine brakes and when they purchased new if they had engine brakes installed they had the mechanics disable them. They had a problem with paying the cost for repairs from the results of an engine brake.
The allison transmission does have some braking ability because of the gear you chose to be in when you start down a grade. Starting down a grade at the speed you want to be at when you get to the bottom is good practice.
Having said that I admit that my MH has a brake and I rely on and use it often!
My point is that you do not absolutly need the engine brake and it may cost you extra money in maintainence. But having one is nice!

[elainee]

Originally Posted by Mike Canter

Jim is 100% correct. I just read up on the motor and it has an integral exhaust brake that works off the new design VG turbo. This is what Cummins says......

The Holset Variable Geometry Turbocharger (VG Turbo)
provides exhaust braking without additional add-on
hardware in the exhaust system and eliminates exhaust
brake maintenance. The operator activates braking by
using the brake switch in the driver’s compartment. ISB
exhaust braking assists in stopping the motorhome while

reducing wear on the service brakes.


Check on page four of the Cummins engine data
http://cumminsengines.com/assets/pdf/4971103.pdf

mike is right on...
i have the vg turbo on the isb 6.7 cummins..works great coming off the interstate and most of the time requires very little foot brakeing at the very end . you will appreciate it when driving down 3-6% grades. however the only time i do'nt apply the turbo brake feature is when driving in slow city traffic because of he "hunting" effect during the accel and decel traffic condition.
peter d
09 tiffin allegro red dp

[Vegasguzzi]

Thanks for all of the help. The odd part is the owner did not think there was an engine brake or effect. After 20k miles I would think as the owner/driver you would notice a button or switch.

[J Walker]

Not having the variable turbo geometry engine I don't know much about it, but I assume that it employs automatic downshifting as does exhaust brakes. That feature is essential for assisting braking and the owner of the Ventana should at least be aware of the downshifting. Feeling the effect of the variable turbo would be difficult as is the effect of the exhaust brake. The biggest effect that is noticed is downshifting and that is when a lot of braking occurs.