Curious questions

[tree98]

(02-28-2019 )rraccerr Wrote:  2014 t680 with a ISX 15 400 Cummins. Two questions i would need help with.

1. My sweet spot on my rpm meter is at 1300 rpm. That’s where I keep my engine running over the road. But I read that an ISX should be kept at 1650-1800 to get best performance, is this true? And if so, should I forget about that sweet spot indicator?
2. I would like to be as effective as I can to fix my own truck and I’m searching for the best way to purchase the insight and inline products. The best way to get everything I need to start my own diagnose and repair. A lot of online stores offer diffrent prices and deals. I’m confused as to what to purchase that will accomplish the the road I choose to travel.
Any and all help will be much appreciated. Thank you. :blush:

The lower RPM range is hard on the liners. It's a known weakness on these ISX engines. You want to stay above 1500, so if your climbing a hill and you drop to 1500 shift it down a gear, if you drop to 1500 again drop it down another gear. Stay above 1500 on a hard pull. Some guys say 1650 but you get the point. 1300 is quite low in my opinion, the more you lug that engine the sooner you'll have to inframe it.