Diesel JD
Full Access Member
I'd say that's not bad actually given the circumstances. You could probably get 18-20 all day at 55-60mph and highway driving, empty or lightly loaded.
Fuel Milage
- Thread starter jfp3205
- Start date
I'd say that's not bad actually given the circumstances. You could probably get 18-20 all day at 55-60mph and highway driving, empty or lightly loaded.
PwrSmoke
Full Access Member
JPF3205: Nobody has yet mentioned errors in the MPG checking. Have you made any changes in tire size? Any such changes would effect your odometer. Taller tires will cause your odometer to read fewer miles than actually travelled so your calculation will show lower mpg than actual. Also bigger/wider and especially more aggressive tires will cut into mpg (2.4 mpg on my gas truck... carefully measured)
Say you went an indicated 165 miles on 15 gallons... that would be 11 mpg. Lets say your odo was 10 percent low. The real miles travelled was 181.5 miles and your actual mileage was 12.1.
If in doubt finding a straight stretch of road with mile markers and spot check your odometer. If it reads .9 travelled over a measured mile, for example, then you know your speedo is 10 percent off. When I got my '86 in '87, my truck with 4.10s was 10 percent off with the stock 235/85R16E tires (31.7 dia) but in the other direction! I was showing more miles travelled than actual so I really crowed about getting 18-19 mpg. Oddly, going to 285/75R16 tires ("33" 32.8 dia) put the odo dead-nuts on and I started reading 16-17 or so. Then I went to more aggressive tires and 16 was about as good as it got... and again, that very careful checking.
The other thing that caused me to read higher mpg than actual was foamy fuel, which cuts the nozzle off early. To be really accurate, you have to dribble the last 2-3 gallons in.
When my truck was brand new, it's mpg was seldom better than 16 mpg at 55-60. I picked up about 1.5 mpg when I added the Banks turbo. Today, on a good day, I get 15. but in my normal "cycle" 14.5 is about it and my injectors and pump are top notch. Less in winter (1.5-2 mpg) because of the blended fuel and the longer warmups)
Say you went an indicated 165 miles on 15 gallons... that would be 11 mpg. Lets say your odo was 10 percent low. The real miles travelled was 181.5 miles and your actual mileage was 12.1.
If in doubt finding a straight stretch of road with mile markers and spot check your odometer. If it reads .9 travelled over a measured mile, for example, then you know your speedo is 10 percent off. When I got my '86 in '87, my truck with 4.10s was 10 percent off with the stock 235/85R16E tires (31.7 dia) but in the other direction! I was showing more miles travelled than actual so I really crowed about getting 18-19 mpg. Oddly, going to 285/75R16 tires ("33" 32.8 dia) put the odo dead-nuts on and I started reading 16-17 or so. Then I went to more aggressive tires and 16 was about as good as it got... and again, that very careful checking.
The other thing that caused me to read higher mpg than actual was foamy fuel, which cuts the nozzle off early. To be really accurate, you have to dribble the last 2-3 gallons in.
When my truck was brand new, it's mpg was seldom better than 16 mpg at 55-60. I picked up about 1.5 mpg when I added the Banks turbo. Today, on a good day, I get 15. but in my normal "cycle" 14.5 is about it and my injectors and pump are top notch. Less in winter (1.5-2 mpg) because of the blended fuel and the longer warmups)
I get around 14-16 around town and 22-24 on the highway with mine as I usually keep the RPM's under 2400 and it makes a difference in the mileage.A good air cleaner and exhaust makes a difference as well as you can get another 2 miles per gallon by taking the heavy ass fan off and replace with electric one.I also was told that another 2-3 for changing out the rear axle grease to synthetic which I'm going to do in the spring.My truck has a 14,000lb tow package with 4.11's and Locker.
redneckaggie
rebel w/o a cause
generally I see 15 mpg, long highway trips will put me into the low 20s if i stay about 1800 rpm or less. personal worst was acheived just the other day towing a 24 ft stock trailer loaded to the brim with hay, bags, and horses. dont know what the trailer wieghs but there was at least 6k in weight in the trailer, not counting the toolbox full of tools and the three spare tires and about 300 lbs of deer meat, seafood, and elk in the bed. the whole trip was spent at 65-70 and as soon as I started to hit the rollin hills it was mostly 4th gear and max throttle.
