For the truck in my signature, any recommendations on the best highway RPM for mileage? Is lower always necessarily better? It's rolling on four 33" studded snow / ice tires (not the best for mileage). I believe it has 3.55 gears. At approx 1600 - 1700 rpms and at approx 65 mph, it clocked in at 17.1 mpg (running with one passenger). I thought that was pretty good since those tires add to rolling resistance and the winter fuel probably doesn't help either. I do use stanadyne performance formula fuel additive to help and prevent gelling in the cold. I'm running my edge on 5 with a low boost setting on 5 too. Maybe I could do better with a different tune or if the RPMs were slightly different, so if anyone has any recommendations on the best highway RPM for fuel mileage, please weigh in. Thanks.

 

1600-1700 sounds decent. I'm about 1500 with 35" rubber. Taller, narrow tires would help. Wider tires don't help though.

 

I get my best mileage on 4x5 based on overhead computer. But I just use it as a sort of driving coach. I have 225 75 16s on my Dually with 3.55s so I'm up there in rpm range but... another thing I noticed is the faster I'm going with the least ammount of boost is where I get better numbers.

 

I found I get the best mileage is when i keep boost about 5psi or lower on the freeway. RPM seems not to affect my mileage, as on a windy day going 60mph I get the same mileage as going 70mph on a calm day.

My last road trip keeping my boost low the whole way, i hand calc 23 mpg over 580miles. (stock 245's though)

 

i have notice keeping my boost around 5 i get the best MPG but got to remember boost is made by fuel so more boost = more fuel used.

 

Not necessarily. I find the EGT is a much better flag for how much fuel I'm using.

 

Yeah, winter blend fuel is gonna take away about 2 mpg right off the bat. I agree with JBearSVT on driving by EGT. The lower, the better. Also keeping the RPMs btwn 1500-1800 helps.

 

Thanks all. Copy that on the winter fuel. I did not consider that. My four studded snow and ice tires in 285 75 16 do have more rolling resistance, then regular all terrains. I notice the difference as soon as I put them on. Added piece of mind for pulling snowmobiles up north though so it's worth it to me as I always seem to be in foul weather. That said, between those tires and winter fuel, 17 mpg is still pretty decent. I have 85K, I should probably adjust my valves too. They have not been done yet.

 

At 85k your engine aint broke in yet. Adjusting the valves might help alittle, but it certainly wont hurt.

 

"Winter fuel"? Hm.