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Cummins M11 exhaust outlet diameter question

Lindsey97

Well-Known Member
Joined
Dec 5, 2010
Messages
173
Location
oklahoma
hello everyone, i recently purchased my 3rd 10 wheel dump truck. it is a 98 freightliner fld112 with a cummins m11 celect plus 370hp and a 10 speed. performs great with only 122k miles. it is a nice truck overall, and has been converted to a dump truck. my question about the exhaust. the previous owner stated that the truck came with an underbody muffler, and when the truck was converted they added a traditional upright muffler. it has a step down reducer just after the downpipe coming off the turbo. i suspect that the exhaust is too small and could cuase heat problems when pulling a heavy load. i think the exhaust needs to be 5 inch like my detroit series 60. i am considering plumbing my cummins m11 truck for pulling a pup end dump, but would like to be sure that i wont hurt the motor. if anyone has any experience with the m11 in this area i would appreciate the advice. i currently do not have a pyrometer, but will be adding one. the cummins runs 175f until you pull equipment or hit a long hill and run tached out at 72 mph. then it begins to slowly increase engine water temp to 200f. it will cool down immediately when you back out of it.

thanks guys.
 

Cotterpin

Active Member
Joined
Dec 18, 2007
Messages
40
Location
SW. Indiana
Our Case 921's have M-11 engines , 4 " flange on turbo outlet . I guess you could get a 4" flange and step it up to 5 " with a 4 " ID - 5 " OD / 45 or 90 el-bow . Flange pt. no. is 26-405A .
 
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