Who gets the best gas milage

[86swb]

I get about 15 MPG on average with my 350 engine, 700R4, 3:73 Eaton posi real.

[78GMC SIERRA CLASSIC]

Dang i was hoping someone would have got around 20 mpg from there engine with bolt on parts hahahaha I guess you pay the price at the pump but they sure are fun to drive

[bikes&bowties]

20mpg? 6.2 diesel would be your friend.... i want one turboed in a crew

[ChevyC102007]

If Im reading my calculator right Im only getting 9.2 mpg in my 1980 1/2 ton 2wd 350/350 with 255/15 tires. Probably less when I turn into a teen again and punch it hehehehe. I run about 60-65 on the highway and the truck turns about 2650-2800 rpm at those speeds.

Some one told me these dual tank trucks run two 18 gallon tanks, Im not sure if thats correct or not. Dunno what gears I have in the rear but Im already tired of the "one tire fryer". Gonna swap to a 3.42 or 3.73 rear with a limited slip eventually though.

[dga93]

I'm getting around 8.5. I live in the mountains and it hurts the old thing

[flamingbig10]

Originally Posted by ChevyC102007

Some one told me these dual tank trucks run two 18 gallon tanks, Im not sure if thats correct or not. Dunno what gears I have in the rear but Im already tired of the "one tire fryer". Gonna swap to a 3.42 or 3.73 rear with a limited slip eventually though.

16 gallon for short beds, 20 for long beds

[asphaltburner]

Yo! That is correct,...FRANKENTRUCK has two twentys and is a longbed 3/4 ton. It runs about 12 mpg with the custom 350/TH400/NP205, 4.11:1 rear gears, and 33" Firestones.
The engine requires VERY little pedal pressure to maintain 70mph on the highway, even on inclines, due to it's Hp/torque.
Todd.

[3r!c84]

10 last time i did it.but i lowerd it and put some engine mods on so lets seen in a few days

305/350/3.43

[piecesparts]

Originally Posted by asphaltburner

Yo! That is correct,...FRANKENTRUCK has two twentys and is a longbed 3/4 ton. It runs about 12 mpg with the custom 350/TH400/NP205, 4.11:1 rear gears, and 33" Firestones.
The engine requires VERY little pedal pressure to maintain 70mph on the highway, even on inclines, due to it's Hp/torque.
Todd.

That calculates out about right, with your tires and gear ratio, you are running down the highway at about 2900 RPM. I am surprised that you get 12 MPG with the extra drivetrain components. I run at 2500 at 70 and I can pull 15.5 to 16 MPG on the 383 stroker engine with the 3.73 gears.

[csa daddy]

i had a 68 chevy with a 350 sb an a 700r4 in with a 31 inch tire with 3.73 gears an i got probly 17 or 18 miles to the gallon might have been a mile or two better dont really remeber

[dammitmitchell]

3-12 mpg hehehehe

i wish i had some sort of "gas mileage" but whatever... i can park on cars..

[asphaltburner]

I have been known to get on it a bit,...
Todd.

[Rascal_one2001]

i get 16 in my 1985 gmc shortbed 305 lockup 350 not sure on gears but my real fuel save is my long bed crewcab 4x4 with 36's tbi454 th400 3.73 8 mpg

[SSC's76]

Originally Posted by 78GMC SIERRA CLASSIC

Dang i was hoping someone would have got around 20 mpg from there engine with bolt on parts hahahaha I guess you pay the price at the pump but they sure are fun to drive

This isnt my truck which gets about 12 city 10 highway but my firebird gets 20 city 25ish highway.

Specs for the 82 bird which isnt light or slow by any means.

5k on rebuilt engine 89 350 stock replacement internals just added a few goodies like a windage tray double roller chain and HV oil pump. Swirl port heads stock valves, crower 00915 cam, edelcrap 1406 carb, performer rpm intake, accel distributor, flowtech 1.5 headers 3in single exh, 700R4 and 3.42 gears on 260 60 14's. This is a great power and economy setup this combo makes plenty of street power but can be driven easy and gets better fuel economy then my wifes 04 ION...... well just seems like that since my fuel tank is bigger.

[ChevyC102007]

I knew my fuel gauge was off, I figured it was about a 1/4 off. I got a few things Im going to put on the truck that will hopefully boost gas mileage abit (Electric Fan, Tune up of course, rebuild the Holley etc).

Junior sees alot of in town mileage and a few highway miles so if thats only in town I guess that aint to bad.

[allancdelco]

6-8MPG on 92+octane boost (11.75:1 CR +40 degrees total advance), its about the power, that's all. Very expensive, (green)brown, daily driver.

[redneckchevy]

My daily driver (1986 chevy C-10 LWB) Gets 12MPG, took it on a 150 mile trip this week end, and i got 12.9MPH. At 55-60 MPH it is turning 1700 RPM. 350/700r4, not sure on the gears.

[piecesparts]

Originally Posted by redneckchevy

My daily driver (1986 chevy C-10 LWB) Gets 12MPG, took it on a 150 mile trip this week end, and i got 12.9MPH. At 55-60 MPH it is turning 1700 RPM. 350/700r4, not sure on the gears.

We put a 700 R4 under my son's truck (86 Chevy SWB with a 350) his mileage dropped to 11.5 MPG. The engine was running around 1700 RPMs and lugging the truck around everywhere. I found a posi 3.73 geared rear end and the mileage went up to 14 MPG with the RPMs on the engine around 2400 to 2500 at cruising speeds of 70 MPH. The chevy trucks do not like to lugged down and when you accelerate, you are using more gas. I just ran my 84 SWB 3000 miles on a trip, and got an average of 15 MPG with times above 16 MPG. As stated--- 383 stroker, 700 R4, with 3.73 gears. I run at 2500 RPMs at 70 MPH.

[redneckchevy]

Originally Posted by piecesparts

We put a 700 R4 under my son's truck (86 Chevy SWB with a 350) his mileage dropped to 11.5 MPG. The engine was running around 1700 RPMs and lugging the truck around everywhere. I found a posi 3.73 geared rear end and the mileage went up to 14 MPG with the RPMs on the engine around 2400 to 2500 at cruising speeds of 70 MPH. The chevy trucks do not like to lugged down and when you accelerate, you are using more gas. I just ran my 84 SWB 3000 miles on a trip, and got an average of 15 MPG with times above 16 MPG. As stated--- 383 stroker, 700 R4, with 3.73 gears. I run at 2500 RPMs at 70 MPH.

Really? hmm... the truck does feel like it lugs to get up to speed and stay up to speed.