(05-14-2022 )Rawze Wrote: (05-14-2022 )StormChaser Wrote: ....
I have a 2017 Kenworth T680 with an ISX 15 550hp engine.
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with 3.32 rear end.
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And by the way... THOSE TRUCK SPECS ABSOLUTELY SUCK!. - That high HP and horrible rear end combination screams "pure engine abuse and torture" right out of the gate without even knowing anything else about it.
A truck that is spec'd with those horribly tall rear ends like that eats the engine up 2x faster than normal. Buying into a truck spec'd terribly like that, for example, if it had 500+k miles on it, is like buying a properly spec'd truck with more than 1.1million on the engine already.
I.E.. TALL GEARED TRUCKS LIKE THAT are set up to "cheat the system" for the first owner who does not know how to drive a truck properly (or has a driver who holds their foot in the floor all day), .. by lugging the engine to an agonizing death below 1500RPM its whole life, so that it cannot make full power, all at direct the expense of the next person that purchases it later on, when the warranty is up and it gets re-sold.
If you plan on keeping that truck long term.. it would be wise to invest in a proper set of rear ends for it that match your trucking operations and keep you from lugging it below 1500RPM everywhere ... just saying.
On this specific, my truck is not lugging below 1500. At 70 mph my RPM is right at 1500. It is 1700 when going 75, and 1900 at 80. I rarely go 80, and tend to keep my truck at 70 mph. I know that Cummins are built for high resolution. What RPM do you recommend for cruising?
