Ram HD 1000 lb-ft MPG loop
Towing 29k. Nice to see they have a gauge that tells you how "full" the DPF is now. That's handy.... VIDEO Almost 9mpg pulling 29k, which means about 37,000 GCW. Pretty incredible. Interesti...
Forum Discussion
ShinerBock wrote:
Sizing the engine
And THIS is why you have to be careful cherry-picking quotes to only suit your agenda Shiner. Did YOU read the entire article you posted?
He emphasizes that before making such a decision it’s crucial to study the expected duty cycle for the truck. “If the truck is going to be loaded close to maximum or operate out West or through Eastern mountain ranges on a consistent basis, we would recommend the customer spec an MP8 with the lowest horsepower to get the job done,” McKenna explains.
Read that very clearly - what word did he use? Duty Cycle
Why does he advise you to select the LOWEST hp, only to up-rate it later for resale? It's because it affects engine life at high duty cycle, despite them all being "emissions certified".
“Our 13L MX is integrated into all of our models except for refuse trucks,” Sproull relates. “It can handle GCWs up to 130,000 lbs.; get beyond that, and the ISX15 would come into play.”
Notice above a GCW he made a cut-off based on DISPLACEMENT? We know the upper end of the 13L rating (485hp) overlaps with the lower end of the ISX15 rating (400hp, EPA13). Why didn't he simply say: beyond 130k lbs, use a 450+ hp engine?
Because a 485hp 12.9L has lower longevity that an ISX15 @ 485hp.
Starting from the top, Jones says that Cummins regards the 15L market as very stable “and one that we might argue will grow. There’s simply no replacement for (higher) displacement when it comes to fuel economy, reliability and longevity in a 65,000- to 80,000-lb.-GCW operation running mostly on highway pulling loads.”
He explains that with such duty cycles, “higher displacement is an advantage when it comes to fuel economy. The larger engine size enables broader power and torque curves so the engine can be operated at lower rpms than smaller engines for improved fuel economy. Given that as well as the proven longevity of these engines, we simply do not see the 15L market declining.”
He specifically talks about LONGEVITY of the "15L market".
Again, there's hp overlap between and ISL/ISM(ISX12)/ISX15. I've shown you before an ISL can be up-rated to 450hp for fire/emergency/RV applications.
Why don't they spec a 450hp ISL for a 160,000lbs B-train? Because it won't have the desirable service life of a 450hp ISX15. And before you say it, yes, both engines will be operating "flat out WOT", so emissions efficiency is not a concern...
Once again - start a new thread and we can continue the discussion. I have plenty of other sources.
