Uphill gear

My owner's manual says different.

 

What engine?

 

DD15

 

The Detroit™ DD15® Diesel Engine - Demand Detroit | Freightliner Trucks

@Roberts450

 

DD15’s can handle 1800rpm pretty easy as the horsepower rating are at 1800rpm. Im not talking about your SALES BROCHURE listing as they are pushing low rpm for maximum fuel efficiency. Look at all the spec from Detroit and you’ll see its a 2100rpm governed engine

 

No offense to you, but there is a reason why the DT12 transmission shifts the way it does.

I strongly dislike our head engineer for a variety of reasons starting with his treatment of women, moving on to business/economic concerns and he has no clue about the reality of life on the road, but the sob does know his stuff when it comes to design and performance. As much as I want to punch the f'er in the face every time I see him, I do believe what he tells me about engines and their performance. The ahole says that running a dd15 over 1600 rpms causes "damage" (reduced lifetime performance), I believe him.

 

I sure hope not because the one I drive has 3.70 rears and turns 1650 rpm for long periods . It’s only at 900,000 miles pulling a mixture of light in summer and around 95,000 plus in winter. Other than the oil pickup o ring replacement and valve adjustment it’s never been open.

 

So why does the DT12 pulls hills at a max of 1600 RPM?

 

The only thing you'll hurt running the DD15 (or most any big diesel) at 1800 RPM is the fuel economy. Typically most are rated for 2100-2200 RPM

@Roberts450 is 100% spot on.

Think about it. If the engineers didn't want it running over 1800 RPM, they wouldn't let you take it that high (and higher) with the pedal in the first place.

 

That's due to the transmission tuning. Engine is making peak power at around 1600 RPM. It has nothing to do with the engine not being able to handle higher RPM.