So I'm gonna be building either a 12v or a 24v for a dually I'm putting together and was just curious as to which one I could build to make the best MPG but still have a respectable HP number. And also at what HP does either one start pouring soot? I don't wanna be covering my 5th wheel with soot every time I hook up.

Thanks in advance. And as you can tell I'm fairly new to the cummins side of diesels.

 

If MPG's is what you looking for with a decent HP number, I would go with a 12 valve. I'm hovering between 370 and 400 ponies, MPG's are around 21 to 24 going down the highway, and it only puffs when I hit the throttle, and clears up immediately. Mind you, i'm running 3.55 gears with 33's. I would imagine that a dually would be a little harder on fuel, but not to much.

With my trailer hooked, atv in the box, I get a solid 19 mpg going down the highway at 60 mph (95 to 100 km/h).

Smoke is pretty easy to control with a 12 valve. Tune the AFC properly, and you'll get very minimal smoke like I do. Ppump is the way to go my friend. Not taking anything away from EFI as you can tune them to no end, but a properly tuned 12 Valve will get them job done very well, and not have to worry about electronics malfunctioning, and fuel pumps dying.

That just my 2 cents.

Corb