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Theories on the 2025 6.4

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SolidAxleorBust

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Since only the Diesel mattered to Ram, we are left with out any info on the revised 6.4 other then a loss of HP. Theoretically I doubt fixes to manifold/ Coolant passage issue or lifters. But will this just be an emissions choke, or might they have made tweaks in efficiency to reduce emissions?
 
Since the 220amp alternator is now the standard, maybe the recalculated the base hp with the 220amp additional draw resulting in 5hp loss. That said, 5hp loss from a slightly larger alternator on a big V8 seems excessive
 
What is/was the base alternator? 180?


Sent from me
 
I agree it would be nice to know what, if any, material changes are made.

As for the 5 hp drop, that won't be discernible, just doesn't matter beyond wondering why. Kind of like thinking you can't tow as much because you're running the air conditioning.
 
el_barto said:
Since the 220amp alternator is now the standard, maybe the recalculated the base hp with the 220amp additional draw resulting in 5hp loss. That said, 5hp loss from a slightly larger alternator on a big V8 seems excessive
Click to expand...

Likely not, it’s probably less than 1hp required to run the larger alternator.
 
AH64ID said:
Likely not, it’s probably less than 1hp required to run the larger alternator.
Click to expand...
Yeah I mean that’s my only theory I can think of unless it was retuned for emissions reasons. I switched from the factory 180amp to the upgraded 220amp and didn’t notice any difference, but the 5hp drop would be indiscernible anyways considering we are talking about a ~1% difference.
 
If I had to guess it's due to enhanced catalyst to reduce emissions. A visual inspection would be the giveaway to see if those huge California compliant convertors are present. But I also wouldn't dismiss a tuning change to reduce fuel/air.
 
Derated to make the $13k upgrade to the Ultimate In Performance Cummins even more appealing ???
I am not sure the engine HP ratings take into account accessories? If that were the case, they'd have to advertise different HP/Tq numbers depending on if you optioned the dual alternators (and what size those were)
I'd imagine the ratings are bare engine on a dyno numbers, but that's just a swag.
My guess is it's likely something to do with emissions, or they went back and looked at the weakest link in the powertrain and said "geez, we should trim a touch of horsepower off that Hemi, just to be safe" like the cab and chassis engines tend to get derated. Or it's an advertising glitch... lol
 
Maybe the engine horsepower testing facility was moved to Denver.

 
What would be the weakest link? Seems like these engines could handle a fair amount more power. The weak links are lifters and manifolds. Some where I thought I saw a reference to a new lifter supplier for 2025. Maybe they tweaked something to make these engines last longer with out lifter failures. That I would be happy to hand over power for.
 
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