Help comparing 2 isx engines
04-08-2021, (Subject: Help comparing 2 isx engines ) 
Post: #1
Help comparing 2 isx engines
In a moment of poor judgment or maybe good judgment I bought a truck that needs the engine torn down to see what’s wrong (coolant suddenly in the pan, smells like burning oil, coolant and fuel all at the same time as well as missing and steamy blow by) and a spare motor (supposed low miles) I’d like some help with quicksrve comparing the two. I paid wrecker prices for the both so if they’re junk I’m only out my time to tear down.

I’m hoping to make one good runner out of the pair of engines. The one in the truck has a new turbo, new ecm and reman injectors. The spare is supposed to be low miles but the turbo and ecm were parted out.

I started to look in quickserve comparing the two but I don’t really know what the difference between part numbers are so if someone who knows wants to chime in I’d love feed back. When the shop slows up a bit I’ll pull both pans and heads off and see what’s what.

In truck s/n 79240836 cpl 2733 rated 485/1650

Spare a/n 79301420 cpl 2732 rated 450/1650

Tanks.
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04-08-2021, (Subject: Help comparing 2 isx engines ) 
Post: #2
RE: Help comparing 2 isx engines
The CPL2732 is a converted CM870 engine (old stock) into a CM871 on EPA credits via the factory before it was sold.

The CPL2733 is a true mid-tier CM871.


The head is actually exactly the same although they come up as 2 different assemblies. The valve cam, crank, and other hard parts are also the same.. however...

The CPL2732 has....
4923743 - pistons.
4954888 - Injectors.
3683658 - Injector cam.
4045032 - Turbo

The CPL2733 has...
4923747 - pistons.
4954434 - Injectors.
3684306 - Injector cam.
4045034 - Turbo

-- The turbo difference is unknown. it could simply be that one has the bigger cold-side housing on it and they are identical otherwise... or that they are actually 2 different tiers. If they are 2 different tiers then one will have a 12-point flange nut holding the cold side impeller in place, and the other will have a 6-point flange nut holding the cold side impeller in place. That is something to check, as it makes a difference in programming requirements and also overall efficiency.

-- As far as the other differences, the pistons, injectors, and injector cam are all part of a set to ensure the tighter CM871 emissions, compression ratio, fuelling quantity, injection timing standards. THEY MUST REMAIN AS A SET... even if the engine is deleted ... you cannot just slap in the injectors between one CPL to the other. The injector internal profile for each CPL matches up with the injector cam profile for proper fuelling and injection timing offsets. The pistons are a slightly different compression ratio as well. - These components must remain as a set. They are NOT interchangeable on the fly. You will get mis-matched components and it will not run as efficiently as it should, resulting in fuel mileage losses, programming mis-matches, and other longevity issues later on.

The programming used should also match whatever setup it has too + whatever truck specs required.


User's Signature: ->: What I post is just my own thoughts and Opinions! --- I AM Full Of S__T!.
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04-08-2021, (Subject: Help comparing 2 isx engines ) 
Post: #3
RE: Help comparing 2 isx engines
Thanks boss. Once they’re both apart I’ll post up the results and see what kind of mutt of a motor we can make up here.

Where in the heck did you find that information? It would explain why they’re both out of 871 era trucks but one popped up as a 870 in quickserve.

The spare motor has been sitting for a decade, I’m really hoping it’s okay inside. FYI this will be for my own use, not over the road making a living or for sale to some unsuspecting guy. It’ll just be a nice looking truck for the shop to use with our pro tote or (someday) a landoll or rgn to go get customers trucks.
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