riverfishin8riverfishin83s

I tow my fishing boat that is an 16 foot aluminum. When I take it on long trips it down shifts a lot regardless of speed. When depressing the throttle it
feels like it labors. Mileage is 11 mpg. I had an 07 Tahoe with the same engine. Hardly ever down shifted and did 15 mpg at 80 on the highway. Any ideas of what may be the cause. I'm looking at after market items. Afraid of spending a bunch of money and not gaining anything.

SWHouston

It sounds like your 07 might have had a higher ratio rear end gear in it, and was able to deal with the load a little better (less downshifting).

Save for the fuel cost (could be higher) try doing a run with the tranny in 3rd gear instead of "D", and see if that works better (shifting/mileage).

Do you know what ratio differential you have now ?

riverfishin8riverfishin83s

I'm not for sure what the ratio is. In over drive it runs 2500 rpm's at 80 in over drive. I put it in drive and the motor turns 3000. I think I'm going to throw some aftermarket stuff at it to give it a little more torque. Thank you for your input.