Cat 475 vs 550 vs 625

I think, and the Cat guys will correct me if I'm wrong, that the 625 was a C16, and the others were 3406e and C15. I'm assuming that you want a pre EGR engine.

 

Not if they are acerts, the acert was available at all those power levels.

 

The 600/625 acert uses 17:1 compression pistons, the lower HP engines use 18:1, this makes a difference when the engines are tuned.

 

ideally when buying a cat motor truck, stay away from acert motors. What you want is anything before 2003 before acert came out. Sounds like you want C15 motor with serial number prefix 6nz. Or of course a 3406. Who doesn’t!?

 

MXS and NXS engines are not bad engines. They had their issues when they came out, but once all the upgrades were done, they are reliable engines. Sure, a 6NZ is a better engine, no denying that, but I would rather have a NXS in a truck that is much better condition overall.

As far as power, I attached the uprate chart for Acerts so you can see for yourself what your factory tune options will be.

 

The problems with the acert lies with the programming used to meet emissions, they have the best rotating assembly of any truck engine cat built.

6nz engines are over rated.

 

Yeah sorry. Just something I never knew that they got the bugs worked out. I’ve just been a fan of not dealing with any emissions motors

 

And fuel economy... The 475 is a much better all around engine. Still great power and far better economy than the big HP motors.