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CM 2350 CPL 3937 power questions - PlasticCowhauler - 02-20-2026
Hi all. I have a de-mandated CM2350. CPL 3937. It still has the stock VGT turbo and has coolant bypass for the back cylinders. Now I don’t know much but I’d like to learn. I’m trying to get more power and better fuel economy out of this engine. I haul cows and hay grossing anywhere from 90-130k. I’m getting 4.5-5.5mpg doing this. Some people tell me I need to just get rid of the VGT turbo and I was thinking of going that route until I did a bunch of reading on here. That does not sound like the best way to go (and I really like my Jake’s). So please enlighten me on what I should do. Turbo is the original and truck has 970k miles on it. Should it be replaced? Can I hire someone on here to do remote tuning? If so what type of computers and software do I need?
Thank you all in advance.
RE: CM 2350 CPL 3937 power questions - Rawze - 02-20-2026
== Removing that VGT is the death of the engine. You loose all friction and precise fuel-air-mix control, and a whole lot more negative things happen that shorten the life of the engine + lower fuel efficiency by a LOT over time. - Anyone who would even suggest removing that VGT is a complete idiot! who lives under a rock.
== Just to set the mood: There is no such thing as 'Better Fuel economy' and 'More power' in the same sentence. - You figure that one out and you will be the richest man in the universe, as you would have figured out how to break reality and the laws of physics. - It takes MORE FUEL to make more power in an engine ... NOT LESS!.
Removing/Repairing BAD Delete Programming can and will improve fuel efficiency, but it is simply because a lot of energy was being lost to the engine fighting itself internally (all while the driver w. It tearing its own guts out over time. About 90% of all tuning programs that I see every year suffer these issues.swears it rins smooth)
- Other than that, there is no such thing as some kind of miracle-grow, magical tuning fantasy that somehow makes mpg go up in some magical way.
Bad programming aside, ... It takes BETTER DRIVING HABITS, better gearing, etc. makes for more efficient operations and overall lower fuel consumption... not some hidden secret extra-special engine program settings.
Is it de-mandated?. - The first thing to do is copy the program from the ecm and e-mail it to me for e proper review to ensure its safe and so that power/torque/etc. can be edited if need be.
info: https://rawze.com/forums/showthread.php?tid=8425&pid=72945#pid72945
== What is the engine ser#?.
== What make/model vehicle?.
== What rear end specs and tranny does it have?.
A truck that is not properly geared and spec'd for 90-130k freight is far worse of a dog than trying to change the engine's power rating. Screwing with the most expensive component in the drive train (the engine itself) is NOT the way to make it pull and operate better otherwise.
related info...
http://rawze.com/forums/showthread.php?tid=7627&pid=66994#pid66994
...
http://rawze.com/forums/showthread.php?tid=10109&pid=83906#pid83906
...
http://rawze.com/forums/showthread.php?tid=8237&pid=71572#pid71572
RE: CM 2350 CPL 3937 power questions - PlasticCowhauler - 02-20-2026
(02-20-2026 )Rawze Wrote: == Removing that VGT is the death of the engine. You loose all friction and precise fuel-air-mix control, and a whole lot more negative things happen that shorten the life of the engine + lower fuel efficiency by a LOT over time. - Anyone who would even suggest removing that VGT is a complete idiot! who lives under a rock.
== Just to set the mood: There is no such thing as 'Better Fuel economy' and 'More power' in the same sentence. - You figure that one out and you will be the richest man in the universe, as you would have figured out how to break reality and the laws of physics. - It takes MORE FUEL to make more power in an engine ... NOT LESS!.
Removing/Repairing BAD Delete Programming can and will improve fuel efficiency, but it is simply because a lot of energy was being lost to the engine fighting itself internally (all while the driver w. It tearing its own guts out over time. About 90% of all tuning programs that I see every year suffer these issues.swears it rins smooth)
- Other than that, there is no such thing as some kind of miracle-grow, magical tuning fantasy that somehow makes mpg go up in some magical way.
Bad programming aside, ... It takes BETTER DRIVING HABITS, better gearing, etc. makes for more efficient operations and overall lower fuel consumption... not some hidden secret extra-special engine program settings.
Is it de-mandated?. - The first thing to do is copy the program from the ecm and e-mail it to me for e proper review to ensure its safe and so that power/torque/etc. can be edited if need be.
info: https://rawze.com/forums/showthread.php?tid=8425&pid=72945#pid72945
== What is the engine ser#?.
== What make/model vehicle?.
== What rear end specs and tranny does it have?.
A truck that is not properly geared and spec'd for 90-130k freight is far worse of a dog than trying to change the engine's power rating. Screwing with the most expensive component in the drive train (the engine itself) is NOT the way to make it pull and operate better otherwise.
related info...
http://rawze.com/forums/showthread.php?tid=7627&pid=66994#pid66994
...
http://rawze.com/forums/showthread.php?tid=10109&pid=83906#pid83906
...
http://rawze.com/forums/showthread.php?tid=8237&pid=71572#pid71572
ESN: 79728278
2015 Peterbilt 579
3:55 Read ends
13 speed
Yes it is de-mandated