Slimchance87

I can run stock tires with 17" rims @ 69 mph and get 17. Something and I put 35" grapplers with 18" stock rims and get 16. Something @ the same speeds. I have yet to figure this out cuz it's 4" tire differance. I dono if that normal that's running just under 2000 rpm

dave ford

bought truck 2009 v 8 4.6 355 gears got empty tank with the deal , except had enough fumes to make station
filled up drove 4 mile city , 75 miles hyw at 65 mph showed 17.5 at home.
my 6 cyl chevy would have done 20.5 mph. ford is for sale if I can get within 1k

F150 going 150

I managed to do 840km (522 miles) on a 120l (31.7G) tank, my edge at the end of the trip was 9.6 l/100 km(24.5 MPG) . sitting at either 90km most of the time or 110km the rest of it, revs at 1800-2000 whenever possible

Red Fire

I have a 2010 f150, supercrew, 4x4 with 223660 km on it. Mileage was previously 800km city driving and 1000km highway. In the last two months I have lost about 100 km in mileage/km per tank. Recently I had changed the fuel pump module because it just went out on me as I was driving. I even added the seafoam treatment to the gas, oil and throttle body and changed the air filter. However there doesn't seem to be any change. The guage now shows 21L/100km but I recalled the monroney sticker stating 13L/100km on street and 11L/100km on highway. I drive an average of 120km + - 10km going to work and about 100km going home. Although I can see this as a reason for the jump, it is the same way I was driving before the mileage loss. I think I was getting about 16L/100km then. I am told that it can't be the fuel filter since it is in tank and there is no engine light on. Any other ideas here? I'm going to try stepping off the gas for a full tank and see how that goes. 100 km on highway, 60 km on streets.

ShirBlackspots

It's not RPM, but speed you should be concerned with.

About 80kph (50mph) is where our trucks get the best fuel economy, because just before that is where the torque converter goes into lockup mode (you'll see the tach drop about 200rpm when it locks under light acceleration)

dukedkt442

Because ALL our trucks have the same final drive ratio and wind resistance?

My truck did best at 62 mph exactly. 50 mph had it lugging it’s *** around locking/unlocking the TC. Gas engines are most efficient in their powerband, and mine was well above whatever rpm 50 mph had it turning.

Red Fire



marshallr

Exactly, and that changes under varying conditions. It is hard to put into words, but you have to "drive" the truck. Not let it drive you. It's a sort of a seat of the pants feeling about which gear you need to be in and match the rpm's to the conditions. Just because you're at 1500 rpm's that doesn't mean you're using less fuel than at 2500 rpm. If the engine is struggling at 1500 to maintain speed it will use less fuel by dropping down to a lower gear and getting the rpm's up where they need to be. And even with an automatic it works better if you lock out higher gears to get the truck up to the proper rpm to get up inclines before the transmission does it.

If I'm cruising along on a back road where speeds will never be over 50 mph I lock out 5th and 6th gear and let it run in 4th at about 2000 rpm. Performance and fuel mileage is better. If I don't lock out 5 and 6 the truck keeps trying to go to those gears and run at 1500 rpm. The truck has no power and the engine is working too hard. In mountains at altitude I do the same, but get the rpm's up to 2500-3000 for best performance. Cruising on level interstate at 70 mph then it's 6th gear and 1700-1800 rpm.

Red Fire

Thanks guys, I appreciate the quick response. Will let you know in a couple weeks how it went.

DarrinT04

Between about 53-58 imo