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Old 05-27-2018, 08:02 PM   #1
mre
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What is Normal Exhaust Brake Performance

I have the below coach with a Cummings 360 and an Allison 3000. My question is about he exhaust brake. I feel it is not very aggressive.

I had a 2011 Chevy Duramax Allison. The exhaust brake would hold the truck and 5th wheel when descending a hill or mountain. It had an upshift point of about 4500 while descending. It always seemed to be able to hold the truck and 5th wheel at a steady speed while descending and I don't recall it ever reaching the point where it upshifted. Not so with Cummings. It will up shift at 3000 rpm and doesn't seem to be able to hold the coach while descending even some mild hills.

Is this normal?

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Old 05-27-2018, 08:59 PM   #2
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Quote:
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I have the below coach with a Cummings 360 and an Allison 3000. My question is about he exhaust brake. I feel it is not very aggressive.

...

Is this normal?
I am not up on the Ventana series as much as I am the Dutch stars. Just to clarify do you have an exhaust brake (one stage) or an engine brake (two stage)?

If it is an exhaust brake I am not surprised that it is not very aggressive. My 2006 Dutch star only has an exhaust brake which is not very aggressive.
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Old 05-27-2018, 09:16 PM   #3
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I am not up on the Ventana series as much as I am the Dutch stars. Just to clarify do you have an exhaust brake (one stage) or an engine brake (two stage)?

If it is an exhaust brake I am not surprised that it is not very aggressive. My 2006 Dutch star only has an exhaust brake which is not very aggressive.
One stage.
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Old 05-29-2018, 07:58 PM   #4
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I am not up on the Ventana series as much as I am the Dutch stars. Just to clarify do you have an exhaust brake (one stage) or an engine brake (two stage)?

If it is an exhaust brake I am not surprised that it is not very aggressive. My 2006 Dutch star only has an exhaust brake which is not very aggressive.
I have a VGT engine brake. It is a single stage.


I have read some more on this and it appears that what I am experiencing is normal.
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Old 05-29-2018, 09:50 PM   #5
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On my DS the engine brake is one stage. It holds me fairly well on moderate declines. Over about 5% grade I have to use the service brakes as well. I don't know how much better it would perform if the toad was not attached.
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Old 05-29-2018, 09:55 PM   #6
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I have a VGT engine brake. It is a single stage.


I have read some more on this and it appears that what I am experiencing is normal.


Not sure about this but I believe a VGT (variable gate turbo) ‘engine brake’ is actually an exhaust brake- if you want to get technical.
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Old 06-01-2018, 10:29 AM   #7
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My 3000MH is also not aggressive but...
For it to work better: lower your speed so it is in third gear by using the service brakes and engine speed is about 2000 rpm. 4th gear is not low enough.
Remember down hill same gear as up hill.
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Old 06-01-2018, 10:42 AM   #8
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At the summit slow to 45 mph. Remember it's much easier to speed up than slow down .
Exhaust style brakes work best at higher RPM and yes the trans will shift up to prevent engine damage.
My Cat will up shift at 2750 and down shift at 2000. I use the service brakes to keep the RPM in that range.

To compare the exhaust brake performance , between your coach and your P/U , 5er combo, you need to compare both rigs exhaust brake HP and throw overall weight of both rigs, into the mix.
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Old 06-01-2018, 02:10 PM   #9
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I contacted Freightliner this afternoon . I discussed the engine brake issue with them. What I experiencing is not normal. I will have to take it into Freightliner when I return from our trip.
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Old 10-16-2018, 11:46 AM   #10
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I am the OP.

Because of traveling and an accident DW suffered, I have been delayed getting the Ventana into Freightliner for the Engine Brake Issue. I will spare you the details of today's events, but they suggest I go for a test drive with a Tech. He brought his laptop to observe performance of the engine and trans. In a nut shell, everything is normal. I told him my observations transmission performance and discussed my experience with the 2011 Chevy D/A that had an exhaust brake. He told me that the Cummins engine brakes are on the weakside compared to others and that my observations were normal.
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Old 10-16-2018, 02:31 PM   #11
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We did a recent trip up 395 in California which has plenty of long 6% grades and I found that with my Cummins/Allison combo any speeds over 50mph required service brakes but if I crested the hill at 45mph I could ride the exhaust brake all the way down the hill regardless of length without having to touch the service brakes.
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Old 10-16-2018, 02:38 PM   #12
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Quote:
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Not sure about this but I believe a VGT (variable gate turbo) ‘engine brake’ is actually an exhaust brake- if you want to get technical.
Totally different. Engine brake uses the engines valves to add braking. Exhaust brake closes off the exhaust with a flapper valve.
VGT closes off the turbo.
My engine brake combines the valve actuation and the VGT
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Old 10-26-2018, 09:48 PM   #13
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I'm glad I have the "engine brake" (exhaust brake) on my 2018 Ventana with the Cummins 360 ISB engine, but it's definitely not as effective as my 2015 Ford F-350 6.7L diesel. My 2007 F-350 6.0L had the traditional turbo lag time and so does the Cummins ISB. The 6.7L Ford jumped off the starting line. I relied heavily on the exhaust brake while pulling my 16,500 lb 5th wheel and continue to use the exhaust brake on my new coach, but it doesn't have as much effect. Of course there is a bit of weight difference.
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Old 10-29-2018, 03:54 AM   #14
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I would tend to think that an exhaust brake on an 8 cylinder Duramax or Powerstroke engine would tend to work much better than an exhaust brake on a cummins. The 8 cylinder engines are a bit higher strung than an inline 6 cylinder cummins... and exhaust brake performance is directly related to engine rpm - the higher the rpm when the exhaust brake is engaged, the higher the braking power.



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