questions about a Cummins ISM turbo

[Bearmtnmartin]

Hi all, I put the driveline from a 2000 Freightliner Century into my 1981 Bluebird Wanderlodge RV. The motor is supposed to be an ISM but the valve cover says M11. Engine model as per the ECM is an ISM500 rated at 425 hp. Serial number is 34963313. So I am confused as to what I actually have. The turbo is not wastegated but most of what I read says the ISM's came with a wastegated turbo. And since there is no wastegate how is boost limited? The reason I am wondering is I am down a little on power. Boost comes in late and slow and will only build to about 27 pounds. I have pressure tested the CAC and piping and it will hold 25 pounds. I have no codes other than low coolant and everything was new when I did the repower. I have new injectors, a new turbo (not chinese) a valve set and filters and oil are good. Just looking to get all the horsepower I can after i did a lot of work to get here. Thanks for the help.

[windowrattler]

According to Cummins lookup it's an ISM-Cm570 at 425 HP. The turbo should be part number 3800856 which uses an air controlled actuator. It could be possible that Freightliner/motorhome company had them modified from what Cummins built?

[Bearmtnmartin]

(12-22-2023 )windowrattler Wrote:  According to Cummins lookup it's an ISM-Cm570 at 425 HP. The turbo should be part number 3800856 which uses an air controlled actuator. It could be possible that Freightliner/motorhome company had them modified from what Cummins built?

The motor is from a semi truck. I bought the whole truck and dismantled it and swapped the drivetrain in. But you are confirming the turbo may be incorrect. When I google your part number it comes up with the same turbo but with a wastegate. But then I dont get enough boost to dump boost anyway.

[windowrattler]

Asked one of my techs about it and he mentioned another customer with an M11. It's in a 99 sterling. It is labeled as an M11 Celect Plus not an ISM CM570. This older M11 uses turbo 3536995 which looks to have no waste gate set up. Maybe someone put the older style turbo on it?

[Bearmtnmartin]

I expect that's probably what happened. The truck probably had 10 owners and i bought it for peanuts because it was thrashed. But how did the m11's regulate boost? Just defueling?

[Rawze]

(12-23-2023 )Bearmtnmartin Wrote:  I expect that's probably what happened. The truck probably had 10 owners and i bought it for peanuts because it was thrashed. But how did the m11's regulate boost? Just defueling?

it should have a waste gate or an actuator of some kind.

someone probably removed it like a fool.

and incorrect power/boost levels can be cause by many, many things. Stop guessing blindly at, put a screen file on it to find out what it is exactly doing...
ref: http://rawze.com/forums/showthread.php?t...3#pid58693

[windowrattler]

(12-23-2023 )Bearmtnmartin Wrote:  I expect that's probably what happened. The truck probably had 10 owners and i bought it for peanuts because it was thrashed. But how did the m11's regulate boost? Just defueling?

I believe you're right about it defueling to keep boost in check. I also believe that the turbo selections are made to match at full power/full fueling. Waste gated turbos and now modern vgt turbos help more in the non full load areas of boost.

One other question in my head would be is the ecm program modified by someone trying to get it to perform "correctly"?

Your engine is 425 horse. What is the turbo off of? As example the customer I looked up with the M11 celect is a 325 horse engine. The turbo would be quite a bit smaller and at max load in your engine I would think it'd be out of it's efficiency range and start to build excess heat.

Rawze is also on the right track with viewing the data but your CM570 might have drastically differently names for the parameters. I was messing with a 99ish ISL CM550 and all the parameters were more of abbreviations and the descriptions of them were poor or non-existent so it took me a bit to find the info I was after.