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Topic: Exhaust brake ISM (Read 2506 times) previous topic - next topic

Exhaust brake ISM

So oldguy installed a really enviable Jake on his ISM. The latest trend has been to do both the jake and a exhaust brake. The combination works well and is quiet. They said that the exhaust brake was about 60-80% of the jake. Used complete Jake brakes are about 2k for the ISM and a new pacbrake valve is about $1300 new. Plus installation on both.  I had never thought about it prior, but I think the Pacbrake by itself would be all the additional I would need. Jake also needs ECM reprogramming. Still been looking for a complete Jake, but was wondering if anyone has installed a exhaust brake on there ISM and what they thought. Couldn't find any history. All input would be appreciated. I do tow at capacity and operate in the mountains.
PacBrake PacBrake C40204 5 In. Prxb Exhaust Brake - Cummins Ism/M11

PacBrake Pacbrake C10224 Exhaust Brake Control Group - ISM

Scott

Re: Exhaust brake ISM

Reply #1 –
Scott I didn't  have to have the ECM reprogramed, it was already programed for a Jake
Brake. The only thing I had to do was add a couple of wires into the ECU. The wire for
for making the Allison shift down was hooked up and ran up under the dash by Foretravel.
That needs to be hooked up for the Jake or an exhaust break. I used a separate switch for that
so I can choose to use it or not. I had a exhaust brake on a 8.3 Cummins and worked but not
like the Jake but I have no idea how it would work on a M11.

Re: Exhaust brake ISM

Reply #2 –
We have a exhaust brake on our 8.3.  We've been over the Rockies a few times, and I found it helpful.  I know it's not a retarder, but it's better than nothing.

D-Celerator Exhaust Brake

The way I understand the exhaust brake function, it depends on back pressure in the engine to produce the braking action.  The higher the back pressure, the better it works.  Maximum back pressure is generated at maximum allowable RPM, so proper gear selection (automatic or manual) is critical.  I found our exhaust brake works best in 4th gear at 2200-2400 RPM.  This combo will allow our coach (plus our 4000# towd) to descend very steep grades at about 40-50 mph with only occasional  service brake usage.

I would think (just guessing here) that for any given back pressure, a larger engine would produce more braking effect.  So if I'm right, a exhaust brake would work better on the ISM than it does on my coach.  But, of course, the ISM is mounted in a heavier coach, so that might cancel out any benefit gained by the larger displacement engine.

Re: Exhaust brake ISM

Reply #3 –
Scott, be aware that the post turbo mounted Pac brake will likely cause an increase in EGT when on the throttle.  We installed a few on the smaller engines in the pickups back in the day, and after our testing, decided to sell the US Gear D-celerators instead.  These were mounted downstream and did not affect EGT from our testing.  It also didn't "hit as hard" when you engaged it since it had to build pressure in the piping.

The earlier engines required a valve spring upgrade to work with the increase exhaust pressure....kinda doubt the ISM would need that, but something to verify.

You need additional braking beyond what the retarder will do?

Re: Exhaust brake ISM

Reply #4 –
Curious why the EGT would climb under power. The pac valve should be wide open offering zero resistance. The retarder temperature exceeds what I'm happy with on long descents like eastbound on 70 into Denver if used beyond level one or two. Yes you can run the temp way up and change oil more often but I prefer to keep it below 255F, so yes I would like to have more coach braking retarder capabilities. All roads end up leading back to a Jake brake. You bring up a good point about exhaust valve springs. Keeping the speed down and the RPMs higher helps significantly, and addressing increasing speeds with service brakes is acceptable and I feel I've never had to use excessively but it wouldn't take much more to completely control decent without use of the service brakes.
Which brings me back to what I originally asked if anyone with a ISM installed a exhaust brake and what did they think of it? Peter has installed the Jake and it genuinely makes me think I will also follow his path eventually. Also good to know he didn't have to get ecm reprogrammed. That's another 350-550$.
Scott

Re: Exhaust brake ISM

Reply #5 –
Just spend a little extra and install the Jake. It's the cat's meow. I've left it on since we bought the coach 13 years ago. I pay no attention to it only checking the air pressure at the top of a grade and selecting the gear I want to descend the grade in. It effects no engine or transmission temps or operating procedures.

Since we live in the Sierras, it's in use constantly and if it had any shortcomings, they would have shown themselves years ago. 95% of our trips go up Donner Grade and down the other side on I-80. Drop a gear, listen to the radio, enjoy the view and relax.

Pierce

Re: Exhaust brake ISM

Reply #6 –
Quote from: dsd –
Curious why the EGT would climb under power. The pac valve should be wide open offering zero resistance. The retarder temperature exceeds what I'm happy with on long descents like eastbound on 70 into Denver if used beyond level one or two. Yes you can run the temp way up and change oil more often but I prefer to keep it below 255F, so yes I would like to have more coach braking retarder capabilities. All roads end up leading back to a Jake brake. You bring up a good point about exhaust valve springs. Keeping the speed down and the RPMs higher helps significantly, and addressing increasing speeds with service brakes is acceptable and I feel I've never had to use excessively but it wouldn't take much more to completely control decent without use of the service brakes.
Which brings me back to what I originally asked if anyone with a ISM installed a exhaust brake and what did they think of it? Peter has installed the Jake and it genuinely makes me think I will also follow his path eventually. Also good to know he didn't have to get ecm reprogrammed. That's another 350-550$.
Scott
Our thought (no real empirical data) was that the butterfly basically stops the vortex flow of the exhaust and between that and the 8%ish volume reduction due to it being in the pipe, those things caused EGT rise at all times fuel was being burned above idle.

I too monitor retarder temp now, and want to play with it a bit.  Maybe you've already done this, but as retarder temp builds, if you turn the retarder off for a moment, it will dump the current fluid into the trans and take a new volume in.  Have you tried doing that to see if you can manage retarder temps?  It is something I wanted to try, but my last two trips with the retarder temp gauge working have only been to Havasu, with no real grades to work it on.

Also, I replaced the trans output speed sensor last week and looked at the trans cooler lines.  Big suckers, but sure looks like you could tap in there and add a secondary cooler if you want to...they are just AN fittings.  Lots of space to install one where the muffler was.

ETA, I just looked and the cooler line fittings are 1-1/4", which says -12AN.  The cooler is sandwiched between the intercooler and radiator...not the best place.  I wonder how much just adding a second stock cooler into the loop, and putting it on the other side by the AC condenser, would do for cooling?  You're adding a cooler air source and more volume to the system...both win/win.

Re: Exhaust brake ISM

Reply #7 –
Retarder temps spike when you use the service brakes or high notch positions. Manage retarder temps on grade with a lower gear (more RPMs) and one or two notches of retarder.  You should be able to maintain a safe, steady and comfortable speed going down with minimal use of service brakes and retarder temps in the mid 230s.  More RPMs are what increases cooling.  The transmission cooler on my coach is a cylindrical coaxial heat transfer device between hotter transmission oil and coolant.

Re: Exhaust brake ISM

Reply #8 –
Quote from: dsd –
So oldguy installed a really enviable Jake on his ISM. The latest trend has been to do both the jake and a exhaust brake. The combination works well and is quiet. They said that the exhaust brake was about 60-80% of the jake. Used complete Jake brakes are about 2k for the ISM and a new pacbrake valve is about $1300 new. Plus installation on both.  I had never thought about it prior, but I think the Pacbrake by itself would be all the additional I would need. Jake also needs ECM reprogramming. Still been looking for a complete Jake, but was wondering if anyone has installed a exhaust brake on there ISM and what they thought. Couldn't find any history. All input would be appreciated. I do tow at capacity and operate in the mountains.
PacBrake PacBrake C40204 5 In. Prxb Exhaust Brake - Cummins Ism/M11

PacBrake Pacbrake C10224 Exhaust Brake Control Group - ISM

Scott

I know this is an old post, but figured I would post my experience.  I have about 15k miles towing a 20' enclosed trailer that weighs 8900lbs combined on two axles.  I commonly use only the retarder to slow down, and supplement at the end of the stopping event with coach air brakes and aux electric trailer brakes. 

Only once, when I got caught with bad red light timing at the base of a steep hill, did I ever wish for more brake help.  It was a new road, and while I was going the speed limit, it was just too steep for my weight and stopping distance and I really had to stand on the brakes and flipped the retarder to level 6.  I guess if the worse had happened, one could argue that it would be money well spent on an exhaust brake, and in hindsight, anyone would surely agree. 
 

Re: Exhaust brake ISM

Reply #9 –
What I like the Jake is yesterday I was going down and 8 % grade and I was going down at 62
miles an hour and I could hold the speed with with the Jake and just first notch on the retarder
on and off. Mostly off. That is speed I drive mostly so I didn't have to slow down for the hill. I
wouldn't go any faster as that is all the Jake could handle and I was towing a Sidekick.