New RAM HD 1000 lb-ft

ShinerBock wrote:
Because stock engines are tuned(or de-tuned) to meet emissions. They can safely increase power with hurting reliability, but they can't do it AND meet emissions. The notion that stock engines are maxed out in power due to reliability reason is completely false for most engines these days.

No, an ISB 6.7L is no where near maxed out. I have seen it in the dyno test cells at Cummins when I worked there and in the after market. Heck, mine makes over 500 rwhp even with the emissions intact. However, as I said before it cannot do it AND meet emissions.

The reason you have never seen 385 hp in the commercial world is because those engines have to go through different dyno certifications. A pickup goes through what is called a chassis dyno certification since the vehicle it will be going is complete and an incomplete truck(no bed) goes trough what is called an engine dyno certification because the chassis it is going in is not complete leaving the factory. These two certifications have different regulation depending on the emissions bin and tier of the truck it is going in.

It has more to do with emissions rather than duty cycle. Duty cycle will not hurt the engine at higher power levels since the engine will de-fuel(cut power) if any of the sensors detect any of the temps will hurt the engine.

Perhaps I should've been more clear from the start - any time I say "the engine tune is maxed out", or "Cummins had to do hardware change to squeeze out 15 hp", I'm doing so under the assumption that it must pass emissions in the first place.

We all know the 2018 Cummins long block itself, if tuned to 1989 standards, can easily hit 500 hp, PLUS deliver 250k miles of reliable service. So I assumed it was obvious that meeting emissions is the very first requirement to even get out of the factory door.

While different emissions certifications is one of the reasons, it's far from the ONLY reason you won't see a 385 or 400hp ISB from Cummins in commercial application. The predominant reason is duty cycle, a fancy way of saying it won't meet longevity targets at the intended use.

Pickups, RVs, and fire apparatus has the lowest duty cycle; this is where you see 350hp ISBs and 650 hp ISXs. Next would be a Class 4 / 5 truck, then school bus, then city bus / tour coach, then line haul trucks, then heavy spec trucks, then heavy machinery (be luck to see a 240hp ISB on an excavator), and finally gen sets, where you see the most conservative rating.

If you insist dyno certification is the ONLY reason behind a 200hp ISB genset, and 400hp pickup, you'll have to show me some Cummins documents stating so.