New RAM HD 1000 lb-ft

RoyJ wrote:


Not sure why you brought up emissions - of course it trumps durability because not passing emissions means you don't sell engines period! I assumed that was a given.

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.

RoyJ wrote:
In this context, tell me how: a new graphite block, stronger pistons / rods, better flowing head, and turbo geometry is emissions driven. The CP4 pump, sure, mostly emissions. But I simply pointed out how far Cummins went just to improve a relatively minor performance gain.

Most of that is not for emissions per say, but rather to reduce weight for the upcoming CAFE regulations that will include class 2b and above trucks for the first time in the next few years. The turbo and heads help keep EGT's low when coupled with emissions devices and also reduce PM. That is the whole reason diesels went to VGT even though they are not as reliable as fixed geometry turbos, to better control emissions by regulating air and fuel.

RoyJ wrote:
This ONLY happens on low tune engines neutered on purpose for fleet purposes. If you had a 425 hp ISX, then sure, you can go to a dealer and get it re-rated for say 475 hp. But in most cases you won't have a 600hp rating available without at least injector changes.

Yeah, because fleets don't want to pay for the higher power variants of the engine so they buy the de-tuned version even though the only the that separates their from the higher power version is ECM tuning.

RoyJ wrote:
We're talking about an engine tune that's already maxed out. An ISB at 385 hp have nothing left to "tune", without hurting durability. Out in the commercial world, I've never seen one at 385 hp, even at RV and fire apparatus duty cycle.

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.