How to get a Cummins to pull properly

I have a isx 525 cummins with a 18 spd. Can anyone tell me how to get to pull stronger?? It's the first one I've ever driven but i can not find the sweet spot to get it to pull. Have a buddy with same set up but will walk away from me pulling a grade. Thank you in advance for the help

 

Paint it yellow?

 

Haha if i can't figure it out i might have to lol

 

Take it out of truck, chain it to tree.


Done.

 

It's not just the engine.

What rears do you have?
What torque are you getting out the back end?
What kind of trans is it?
Anything else, I know im missing something critical. Just having a brain fart.


Two trucks spec'd exactly the same, one will always pull better.

 

Check CAC for leaks?

 

hqve 3.36 rears 1850 tq eaton fuller buddy has the same thing

 

You should see full torque from this engine starting at 1200 rpm. It will stay there till 1500 to 1600 rpm. This is around the same rpm range where you hp and torque meet each other. Normally I would say keep it lower rpm's but see what happens when you run it at 1500 rpm on the hills. Also what year is it? If it is newer than 2010 check to see if load based speed control is turned on. If it is see if you can get it turned off and then see what you have.

 

I have to beg to differ on the opinion of 1200-1500 RPM. I'm sure he's referring to a newer style ISX than I have, which is a 2000 model ISX 600. Mine INDEFINITELY will fall on it's face if you let it drop to 1500 RPM. Just like you shut the key off. 1550-1700...it's similar to a locomotive. Just a fact of life for this generation ISX, they like their higher sweet spots than the newer versions. Lugging them takes those mid mounted counter bore liners for a bad ride prematurely as well.

I have driven 2011's but they were castrated. I couldn't make those do anything normal, all they did was act numb no matter what. Glad I don't have to put up with that all day, every day.

 

I found the best pulling power on a isx was around 1550-1600.I ran two of them one was a 550hp 2050 other was 525 1850 both had 18 speeds and I believe 3.55's.