New RAM HD 1000 lb-ft

RoyJ wrote:

Because you keep on quoting emissions this, emissions that, as if I never took it into account.

Because you keep saying that power levels are what they are due to reliability and that is not true. They are detuned to meet emissions just like gas engines were in the 70s and 80s.

RoyJ wrote:


Let's think logical for a moment - if an ISB can be tuned that high, what's the point of Cummins making an ISC, ISL / L9, ISM / ISX13?

If an ISB can make 400hp reliability, at any duty cycle, in any application, the you would see them in city buses instead of ISLs. You'd see them in vocational trucks. In 300 size excavators, dozers, etc.

Because they can't reach those power levels AND meet emissions as I said before. Each use for the engine has different emissions requirements which is why the on road version of the 6.7L does not go above 385 hp yet the marine version of the 6.7L makes 550 hp with the same rods, crank, block, etc aside from things such as turbo and other devices the onroad version has to use to meet emissions. Sea water is also used to cool intake air which greatly increases power. The marine version still has to meet emissions, but they are different emissions that are not as strict as what on road and other uses.

Cummins 6.7L for Boats and Trucks - Compare and Contrast

RoyJ wrote:
While you find me a video

Here is the video at 3:43

Why are the 4500 and 5500 rated for less horsepower and torque?

RoyJ wrote:

It's from CAT. On page 3, you can see how they have 5 classes of duty cycle, from continuous to very intermittent.

On page 18, using C15 as a random example, you can see it's limited to:

- 440 hp continuous
- 540 hp intermittent
- 595 hp occasional max

This is ALL assuming emissions targets are met. What I really want to hear from the Cummins engineer is: was duty cycle a consideration between pickup and chassis cabs?

Because duty cycle, GVWR, displacement, and how the vehicle will be used plays into what emissions tier and bin the engine has to pass.

This link will explain further (LINK)

RoyJ wrote:
That's why I said to me emissions is a given. Therefore other than emissions reliability vs duty cycle is the predominant reason.

Going back on your first few posts, you did not mention emissions or say it was a "given" until I explained it. Without the emissions requirements, the engines can make way more power. Again, similar to back in the day where you could have gotten a lot of power out of the old 70s and 80s cars by removing emissions devices and limits.

RoyJ wrote:
Getting back on topic, I stand by what I said - Cummins altered the block, piston, rods, head, and turbo just to gain 15 hp / 70 lb-ft RELIABLY.

If they didn't have to, believe, they wouldn't have. That's a lot of R&D that could have gone to executive Christmas bonuses, if they could just "turn up the boost" to squeeze out 15hp.

The old crank and rods can easily hand 800+hp. That is proven. The heads and turbo(which is the same for the most part) was probably adjusted for more air to allow for higher power numbers while staying with emissions. You also have future power numbers. Cummins will no doubt increase power levels to keep up with competition just like they did from 2007.5 to 2018. All they did was adjust tuning and add emissions devices that allowed them to go from 350hp/610lb-ft to 385hp/930lb-ft. They didn't change a thing to the engine itself.