Ive been getting tired of 10-12mpg out of my 95 7.5 460 gasser. was wondering what you guys get out of a stock 6.9. Ive been looking a neighbors mid 80's 6.9 4speed he bought new and only has 63,000 on it.

what do you guys think a truck like this would be worth, it's super straight and only a little clear peeling on the hood?

also do you think i could expect much power difference going from my 460 to the 6.9, for better or worse?

 

20 mpg is possible but I think 18 is about average.

 

With just a 4speed, you won't see a whole lot of improvement. Mid teens most likely, if you drive it right. A later one with a 5 speed will give better mileage.

 

And you'll be loosing alot of power from your 460.

This engine only makes

170HP @ 3300RPM

325ft. Torque @ 1600RPM


Your 460 makes like 230HP and torque I can't remember.


Not much top end, but LOTS of real low end.

 

My 7.3 with 3.55 gears an E4OD overdrive tranny and a brand new fule system gets 21 mpg on summer fuel on the highway and 15mpg around town. Without the overdrive you would probably average 14-15mpg...

 

truck in my sig....

summer fuel driving how i want-18-20mpg
winter fuel driving how i want-15-16mpg

 

If you don't have OD, drive it like everyone would 20-30 years ago, 55.....

That's what I did this summer with my motorhome, at times I was up at 60, but mostly 55, and I hit 14mpg (full time highway non stop) on a nice flat Florida highway.

'87 6.9, C6, 3.54 gears, dually.


But my camper is also tip top tuned. (fully stock, just a full fresher fuel system from years ago)

 

i got both you and David85 trying out the old school double nickle.
it's surprising how much better economy is 55 or under.it's all about that air.

amosmoses,here's my heavy truck (8k lbs empty) hauling heavy pretty much most of the time,with a large dump bed,and drw.driving like great granny; (except for the hills.i give 'em a good show and let 'er talk 3k+ if she wants and then bleed off up higher to keep momentum.kinda have to drive these old school [at least as n/a] diesels this way if you want to resemble your same basic speed when hauling.)
1993 ford F250HD DUALLY CONVERSION Gas Mileage (chipper truck) - EcoModder.com

 

Hell, I even drive my F150 at 55

 

My truck (85 F250) has a heavy old Stahl service body on it, stock 4 speed, and I don't know how many hundreds of thousands of miles on it, but it smokes and drinks oil like crazy...I don't drive faster than 60MPH, since at 65 it sounds like it's going to explode. Truck is 7300 lbs, and I get 15/19, city/Hwy, if I pretend there's an egg between my foot and the pedal...

 

I average 18-21 on summer fuel. 14-17 winter fuel. i hate winter fuel lol its only got below freezing once or maybe just maybe twice all winter here. i would rather buy some powerservice and treat it myself than take the MPG cut.

 

Yep it's like an additional 10% fuel tax all winter

 

my 9,000 lb 88 with 493,000 miles, turbo, C-6 trans, 4.10 gears and 37 inch tires gets 15-16 mpg if i put an egg under the pedal, and 10-11 if i drive it like i stole it

 

thanks everyone for all the input. i knew not to expect too much better mpg's i figured 15 16 would be fair since i don't hit the highway too often.still, better than 9 or 10 out of my 460. didn't think it put out that low of numbers though. would it really be that sluggish compared to my 460? if so, what would be the easiest/cheapest/quickest was to hop it up a little, get close to the numbers my 460 makes, or maby even surpass it?
thanks

 

There are some things you can do for small power gains, but you NEED a turbo on these motors to get a significant gain. Expect to pay up to $1000 for a complete used setup and I think new is over $3000. Ask your neighbor if you can drive the truck around a little and see what you think.