Many questions

[Rawze]

(04-26-2020 )amermextrucker Wrote:  Rawze,

I drive @ 1450 MT. Would you consider that lugging it?

I don't like pushing mine at 1400-1450 for sustained periods much at all. I try to stay at 1500+ when I need power and below 1400 when barely on the pedal. This is because the ISX is known for having harmonics in the crank and bottom end in the 1400-1450 rpm range. It shows up prominently with bad custom tuning programs/bad-deletes or when the power is at 800HP+ and steps to mitigate it are not taken, so I know it is there, even though it is not likely an issue at all under normal power levels. - Some guys drive them there, I just choose to avoid it out of personal piece of mind/opinion only though. I personally consider the 1450 or so range at the point where you grab your next gear and bring the rpm back up when your foot has to be most the way to the floor to climb that hill.

just my own thoughts on it.

NOrmal power levels and decent programming ... not likely an actual issue... However i have seen plenty of times that had bad programming .. or bad programming and 700+ or 800+ horsepower, literally beat the crank bearings out from around the crankshaft at 1400-1450 rpm becasue of that harmonic on competition engines where a bunch of idiot tuning dips#$its tried to put the screws to them. here is what that looks like ...

(photo borrowed from elsewhere...)