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Author Topic: Cummins ISL  (Read 8383 times)
Ericbsc
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« on: August 20, 2010, 07:01:09 PM »

Anybody familiar with a cummins ISL. I have an a chance to pick one up with an Allison transmission. It is a 400hp unit. The web site sayes 1200 ft lbs. How does this compare with the ISM?
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TomC
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« Reply #1 on: August 20, 2010, 07:25:03 PM »

The ISL is a medium duty engine (about 500,000 mile life expectancy) that is 8.9 liter.  I think it is a great engine for what we do, plus you can get it with a full Jake brake.  It weighs around 1,600lbs, which is about 450lbs lighter then the ISM.  The ISM is a 10.9 liter engine and can be built up to a 500hp and 1550lb/ft torque.  While it sounds like the same rating as the 14 liter Series 60, the ISM does not have the big fat torque curve like the Series 60, so the ISM would be a bit slower up the hill.
I would get the ISL and Allison transmission.  Make sure you get all the wiring, wiring diagram, electronic gas pedal, and electronic shifter with it.  It would be way too expensive to try to put those items together if they were not included. Good Luck, TomC
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Tom & Donna Christman. '77 AMGeneral 10240B; 8V-71TATAIC V730.
luvrbus
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« Reply #2 on: August 20, 2010, 07:40:04 PM »

Eric, there is a guy on the Eagles board that has the ISL in his Eagle I only know what he told me and he says when they are set at 400 hp 1200 lbs of torque is at 2200 rpm and and set at 350 hp 1200 lbs of torque is at 1300 rpm sounds crazy to me but he has told me the ISM or M11 would have been a better choice with the Eagle gearing most of those guys with the Cummins in their Eagles fuel mileage is not that great.
Check there I know Darrel reads but never saw him post if he doesn't answer I will pm his number to you and you can talk to him

good luck
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Life is short drink the good wine first
Brian Diehl
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« Reply #3 on: August 21, 2010, 06:54:14 AM »

Eric, I wanted an ISL for my MCI.  I looked and looked and could not find one used.  I think it is a great compromise between durability and size.  You will not go wrong with it and as a bonus you won't need to extend the rear of your bus to accommodate it.  As others have stated - get the wiring harness for both the engine and transmission, the shifter, the indicator (if there is a separate one), the throttle, and any other misc. parts you possibly can.  I ended up going with an ISM on my conversion.  Here is a link to my site for more details if you are interested: http://home.earthlink.net/%7Ediehls0792_1/BusSection10.html
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luvrbus
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« Reply #4 on: August 21, 2010, 07:02:38 AM »

Eric has a Eagle he can install about any engine in the bus without extending the back his draw back is the gearing and dropbox for the ISL engine
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TomC
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« Reply #5 on: August 21, 2010, 07:43:16 AM »

Luvrbus- ALL ISL engines produce their peak torque around 1200-1300rpm and peak horsepower around 2200rpm.  That 2200rpm peak torque is a typo.  Good Luck, TomC
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Tom & Donna Christman. '77 AMGeneral 10240B; 8V-71TATAIC V730.
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« Reply #6 on: August 21, 2010, 08:04:26 AM »

I don't know oneway or the other Tom but reading the torque curve that engine torque falls in a hurry after or above 1200 to 1300 rpm people do what they want but for a 40,000 lb bus I would go with ISM, the only bus manufactures that used the ISL where the shuttles and school bus guys.
I don't think he would be happy with that engine in a Eagle but it is his choice
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Bob Belter
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« Reply #7 on: August 21, 2010, 10:09:37 AM »

Ahoy, Eric,

I have a 400 hp Cummins M-11 in my 33,000 lb -01 Eagle along with a Roadranger 10 spd transmission. My engine is much like the ISM engine, but with a 400 hp peak.

I'd not go for the smaller ISL engine with less torque.  My nephew has a 400 hp ISL in his SeeYa motorhome  -  about the same weight as my bus.  I get much better fuel mileage than he does.  Some of it may be due to my more efficient transmission.  Other than that fuel  matter, the engine / transmission is quite acceptable to him.

Enjoy   /s/   Bob
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Ericbsc
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« Reply #8 on: August 21, 2010, 12:03:26 PM »

I think after digging into this that the correct liine is that the ISL is a little light for the application. My 05 weighs in at around 38,000 lbs. I also tow a 16' vnose at about 3500 lbs. My 8-71n pulls great at 70-75 mph on flat ground. On a hill with no run it gets ugly quick. Speed is nott the issue which relates more to hp. Power on the hills is where I need the help. The same man said that he has several series 60's. They are the older ddec  11 liter engines. May look at those. Sounds like the 60, or ism may be my best bet. I still have to deal with the rear end gearing. I have a 3:73. at 72mph I am at 2100 rpm which is great for the 8-71 but not a later engine. I was thinking an overdrive tranny would fix that ? Lots of dumb questions, but need to ask LOL!!
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TomC
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« Reply #9 on: August 21, 2010, 01:12:48 PM »

Cummins rates the 400-450hp ISL up to 65,000lbs!  Freightliner is running the Cummins ISL Natural Gas at 320hp and 1000lb/ft torque in regional service up to 80,000lbs picking up overseas containers at L.A. and Long Beach port delivering them in the L.A. area successfully (to the tune of about 600 trucks delivered).  Considering when I bought my first truck in 1980, the standard engine in the trucks was the Cummins NTC 290 with 930lb/ft torque (14 liter), engines are much more powerful now.
I still stick with the ISL being more then enough power, more then a 6-71, 8V-71 (including my turbocharged and air to air intercooled 8V-71) or 6V-92TA.  Yes the ISM will be more power, but then you have to run the very expensive 4000 series Allison transmission, compared to the ISL running the 3000 series Allison (B500 compared to the B400).  Also, remember you have to pay for the larger engines, whether it be the higher price of the parts, the bigger oil capacity at oil change, bigger air cleaners, etc.  Besides, how fast do you need to go up a hill?  Good Luck, TomC
P.S: as good of an engine as the Series 60 is, it is physically way to large to be stuffing in the back of the bus.  I know many have done it, but they are just really large beasts.
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Tom & Donna Christman. '77 AMGeneral 10240B; 8V-71TATAIC V730.
Ericbsc
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« Reply #10 on: August 22, 2010, 02:47:48 PM »

I was looking at my latest fmca mag today and saw a fleedwood 42' coach with tag. It had a 400 hp ISL. The road test report staede plenty of power on start and up to 6% grade!!! Interesting!
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DMoedave
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« Reply #11 on: August 22, 2010, 04:23:37 PM »

Eric, take your time and keep doing your homework as you are. While contemplating our repower we were told time and time again that a 6V71 would be a expensive underpowered mistake. It is all a weight,power and gearing exercise and if done correctly you will have a pleasure to drive and the $  well spent. Good luck. There are alot of great mechanics on the boards and many who have done repowers who dont use the PC. Get to as many big bus rallies as you can. It wont be $ wasted. Good luck
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we love our buses!!! NE Pa or LI NY, or somewhere in between!
Ericbsc
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« Reply #12 on: August 23, 2010, 05:56:09 AM »

Just for comparison, what are the numbers on an 8-71n for hp, and tourqe. I don't know if I have larger injectors or not. Can the 8-71 be reconfigured to get better performance without a loss of durabibilty. I know this is a loaded question, but I jus don't know!!!
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TomC
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« Reply #13 on: August 23, 2010, 08:43:14 AM »

With N70 injectors, and advanced timing, the non turbocharged 8V-71 could be a true 318hp with 866lb/ft torque.  Detroits last build of that engine was a N80 injector 8V-71TA with turbocharging and aftercooling with 400hp and 1200lb/ft torque.  Comparing to the Cummins ISL at 450hp and 1250lb/ft torque.  Also consider that the ISL is about 800lbs lighter, and will last about the same 500K miles before overhaul.  You'll also find the ISL not too much longer then the 8V-71.  Good Luck, TomC
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Tom & Donna Christman. '77 AMGeneral 10240B; 8V-71TATAIC V730.
TomC
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« Reply #14 on: August 23, 2010, 09:37:22 AM »

I finally did some homework and found the dimensions and weights of the 8V-71 vs the ISL.  Here are the results:
8V-71N- 47"L x 39"W x 51"H & 2,310lbs.
ISL- 44.4"L x 27.7"W x 45.9"H & 1,627lbs.

The ISL is 2.6" shorter, 11.3" narrower, 5.1" less height, and 683lbs lighter!  It is a modern 4 stroke electronically controlled engine now with common rail fuel injection that is extremely quiet.   Personally-the choice is a no brainer to me.  Good Luck, TomC
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Tom & Donna Christman. '77 AMGeneral 10240B; 8V-71TATAIC V730.
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