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Old 02-17-2017, 10:45 AM   #1
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ISM500

Looking at coach with a cummins ISM 500hp (2011) Should I have any concerns? Currently have a ISL400hp - flawless to date - hoping for same in larger engine.

Thanks
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Old 02-17-2017, 10:58 AM   #2
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Good engine, unlike the '07 EPA version ISX I have!
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Old 02-17-2017, 10:58 AM   #3
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Originally Posted by Team G View Post
Looking at coach with a cummins ISM 500hp (2011) Should I have any concerns? Currently have a ISL400hp - flawless to date - hoping for same in larger engine.



Thanks

The ISM is a wonderful engine in RV service. Cummins ceased production of OTR ISM engines with the 2010 EPA requirements, so an ISM in a 2011 unit would have been built prior to 1/2010. The EGR valve was the only problematic device on the ISM. Negotiate the installation of an Ugly Fix which will disable the EGR. It only costs about $100 so it's not a cost issue.
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Old 02-17-2017, 11:08 AM   #4
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The ISM is a wonderful engine in RV service. Cummins ceased production of OTR ISM engines with the 2010 EPA requirements, so an ISM in a 2011 unit would have been built prior to 1/2010. The EGR valve was the only problematic device on the ISM. Negotiate the installation of an Ugly Fix which will disable the EGR. It only costs about $100 so it's not a cost issue.
I have the Ugly Fix on my ISX, no issues with it other than trying to find where it goes! The one thing I did notice was that it now takes about 30 miles driving before I get full power. Seems like a little long for warmup.
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Old 02-17-2017, 11:31 AM   #5
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It's really a shame the intermediate Cummins ISM lightweight engine is gone. We can blame the EPA for that as well as Cat no longer selling on road engines. Many folks will buy used just to get an intermediate diesel engine.

The big difference between the ISL and the ISM is low RPM torque.

Clutch engagement torque for the ISL is rated at 575 ft lbs and the ISM at 700ft lbs.
Peak torque for the ISL is 1400 rpm and the ISM is 1200 rpm.
The ISM produces more than 1000 ft lbs of torque at 1000 rpm. It peaks at 1550 ft lbs at 1200 rpm keeps producing 1550 ft lbs all the way up to 1600 rpm.

Engine Weights:
Cummins ISL 1695# 1250 ft lbs @ 1400rpm
Cummins ISM 2070# 1550 ft lbs @ 1200rpm
Cummins ISX 3093# 1650-1950 ft lbs


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Old 02-17-2017, 12:57 PM   #6
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It's really a shame the intermediate Cummins ISM lightweight engine is gone. We can blame the EPA for that as well as Cat no longer selling on road engines. Many folks will buy used just to get an intermediate diesel engine.

The big difference between the ISL and the ISM is low RPM torque.

Clutch engagement torque for the ISL is rated at 575 ft lbs and the ISM at 700ft lbs.
Peak torque for the ISL is 1400 rpm and the ISM is 1200 rpm.
The ISM produces more than 1000 ft lbs of torque at 1000 rpm. It peaks at 1550 ft lbs at 1200 rpm keeps producing 1550 ft lbs all the way up to 1600 rpm.

Engine Weights:
Cummins ISL 1695# 1250 ft lbs @ 1400rpm
Cummins ISM 2070# 1550 ft lbs @ 1200rpm
Cummins ISX 3093# 1650-1950 ft lbs



Agree that Cummins dropping the ISM was a blow to motorhome buyers. The ISM is actually classified as a "heavy duty" diesel, although at the low end of displacement at 10.8 liter. It was purely a "bottoms line" decision. The ISM fuel system had never been up designed to a high pressure common rail. The ISX15 was undergoing a complete top end redesign. Partly for emissions but mostly to correct a design problem that resulted in the #6 cylinder dropping valves and destroying engines. The decision was made to spend the engineering $$ required to up date the ISM fuel system and use much of the ISX engineering to build an ISX12 and drop the ISM.

Loss for owners but simplified Cummins parts inventory & engineering expenditure.
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Old 02-17-2017, 06:23 PM   #7
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Quote:
Originally Posted by vito.a View Post

...Engine Weights:
Cummins ISL 1695# 1250 ft lbs @ 1400rpm
Cummins ISM 2070# 1550 ft lbs @ 1200rpm
Cummins ISX 3093# 1650-1950 ft lbs...


Here's another 500 HP engine to add to the mix:

Detroit Diesel (DD500) 12.8L 2540# 1650 ft lbs @ 1200 rpm
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Old 02-17-2017, 06:30 PM   #8
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Here's another 500 HP engine to add to the mix:

Detroit Diesel (DD500) 12.8L 2540# 1650 ft lbs @ 1200 rpm

The most current weights:
ISX15 3204
ISX12 2880 also 500 hp
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