Yikes!

[bazdan902]

(10-09-2018 )Explosia Wrote:  I have to chime I here, because I bought one of these long legged company trucks. I have a 2.64 rear with a 10 spd.

In 9th gear I can run 63 @ 1400. In 10th I can run 73 @ 1300. I get worse fuel mileage @ 63 then @ 73 when I’m light. When I run California I am in the 6’s, when I run 73 I’m around 7.5.

It is opposite when I’m heavy, if I run 73 It falls to the 6’s, and I get back in the 7’s going slower.

Last week I just ran Indiana to Vegas with 15000 lbs across 70 over the Rockies and Utah to 15 and @ 73 and averaged 7.9

In both situations I watch my boost, but this is a weird truck, it does not like to run @14-1500 rpm. I don’t lug it under 1300 but as for fuel mileage it likes to cruise at that rpm.

Is it a 10spd direct transmission? If so my guess would be you are losing mileage in 9th gear as that transmission is much more efficient in top Gear. If it was geared so you could run 55-60+ish in top Gear you would be a lot better off, also a shorter ratio would help in the hills and you'd be doing this all in top Gear at a more efficient speed/rpm.