Whats you gas mileage on your squarebody truck?

[Grit dog]

I don't remember if I've posted in here but I get 13-17mpg around town depending on how rowdy I'm feeling lol. Hwy ain't too bad, 18-22mpg from 70-80mph and 14mpg at 90+ lol

My truck is the same color and everything and it gets 7-8mpg….so confused…lol.
Maybe less now with the boat anchor tires and wheels…

 

[Grit dog]

I guess I don’t understand the point of all that, if you want a modern truck why not just buy a new/newer one? I guess it depends on your goals and what you want to use it for. I like the idea or preserving something in time but that’s probably an unpopular mentality.

We all doo, but some of us are gearheads and realize you CAN improve on 50 year old technology.
I would 100% LS or Cummins swap a square all day long and twice on Sunday!

 

[Bextreme04]

We all doo, but some of us are gearheads and realize you CAN improve on 50 year old technology.
I would 100% LS or Cummins swap a square all day long and twice on Sunday!

You could always just put the factory injection back on that Gen VI 454 you already have in there. You can even put the CNP setup on it and use the LS computer. Opens up the ability to run factory 4L80 computer control too. The 454/4l80 combo I got for my square came out of a K2500 Suburban with 288,000 miles on it and everything looked completely original and not rebuilt. Still drove 75mph down the freeway with no issues from the place I bought it from to my house to get stripped. Say what you want, but I don't know of any 3/4 ton squarebodies that have that many untouched miles on them and can drive 75mph down the highway comfortably. My 5.3/6l80 equipped 2011 Suburban has 230k miles on it and is still regularly used for tow duty. It has needed regular maintenance and the trans went toes up at about 160k miles... but it will pull a 6500lb trailer down the road at 70-75 no problem and get 10-12mpg while doing it.

 

[Grit dog]

^ @Bextreme04, sounds expensive. And after I add fuel injection, OD trans, tcase and driveline mods, I still got 4.10s and 130lb/ea wheels and tires working against me.
I couldn’t make it get good enough mileage to offset the cost and effort save for maaaybe a diesel swap.
But my 2016 Cummins on 37s that are considerably lighter than the Freedom Wagons wheels n tires, with 3.42s, double overdrive, lower first gear and a deleted common rail only gets 14-15mpg.
It would be a ginormous waste of money to try to improve the fuel mileage on the square. Although when I get time I really want to try to tune up the box stock Edelbroke carb.

 

[mibars]

Has anyone ever done a propane swap? A coworker mentioned they had done that before. Does that improve efficiency at all…also I know nothing about anything to do with this stuff, so if this is a stupid question please don’t berate me lol.

That's a very popular mod in Poland, we use a mix of propane and butane, under the term LPG. Out of every 10 gas powered cars 2 or 3 are LPG equipped.

Biggest benefit: Price. A liter of LPG costs more than twice less than a liter of regular gasoline and due to popularity you can get it everywhere. Also the range adds up as you can still drive on a gasoline if you wish.

There are like six generations of these systems, starting with gen 1 which is well suited for carbed engines, using a "mixer" - A kind of a nozzle that mixes LPG gas with air, however it creates a major obstruction in the intake dropping power a lot. Super simple design, no computers needed. Gen 2 uses similar setup, but with computerized regulator adjusting amount of gas added via mixer, so the AFR is under better control, needed for cars with cat converters. Gen 3 uses nozzles that continuously supply gas, the amount is regulated by the pressure supplied to nozzles. Gen 4 uses injectors similar to gasoline injectors, but meant to inject gaseous LPG, Gen 5 uses liquid gas injectors and comes with LPG pumps, gen 6 is a liquid direct injection via factory gasoline injectors.

I have a Gen 4 in my WRX (I wish I had Gen 5), for our trucks possibly anything up to gen 5 can be made to work if fuel injected, and maybe up to gen 3 for carbureted trucks.

By the way I didn't say a word about drawbacks, and there are couple:
-Possible to wear out engine quicker as LPG is more "dry" than gas, easy to mess up AFR
-Higher fuel consumption, 10-20%
-Adds complexity, tank takes up space (usually mounted in spare tire location), adds weight
-Except for gen 5 and 6 there is always some power reduction, significant in Gen 1 which affects also performance on gasoline, to almost not measureable in gen 4. Gen 5 and 6 can actually increase power slightly due to latent heat of evaporation.

 

[Sgt Gus]

I don't get 16 mph from my 04 burb.

 

[mibars]

I'm positively surprised with my Burb gas mileage on highway:
Conditions: 62 mph/100 km/h driving (GPS speed) for most of the way, some back roads, temperatures over 33*C / 90 F, no A/C, mostly flat, all windows down most of the time, 2 people and some camping stuff on board. Wheels are 285/75/R16 if I recall correct, that's about 33", aired to 2.3 BAR

Result: 13.6 L/100 km or 17.3 MPG!

I was prepared for at least 15 L/100km / 15 MPG after when I bought it, drove at similar speed for about 100 miles and got 18 L /100 or 13 MPG, but with the oxygen sensor dangling under the car and tires at about 1.8 BAR

 

[DoubleDingo]

I'm positively surprised with my Burb gas mileage on highway:
Conditions: 62 mph/100 km/h driving (GPS speed) for most of the way, some back roads, temperatures over 33*C / 90 F, no A/C, mostly flat, all windows down most of the time, 2 people and some camping stuff on board. Wheels are 285/75/R16 if I recall correct, that's about 33", aired to 2.3 BAR

Result: 13.6 L/100 km or 17.3 MPG!

I was prepared for at least 15 L/100km / 15 MPG after when I bought it, drove at similar speed for about 100 miles and got 18 L /100 or 13 MPG, but with the oxygen sensor dangling under the car and tires at about 1.8 BAR

That is good mileage for a rolling brick

 

[newguy11]

That is good mileage for a rolling brick

You must be registered for see images attach

 

[Redfish]

But my 2016 Cummins on 37s that are considerably lighter than the Freedom Wagons wheels n tires, with 3.42s, double overdrive, lower first gear and a deleted common rail only gets 14-15mpg.

Look, I am usually aligned with you but you have definitely crossed a line here. You cannot be telling people that your Cummins diesel isn't getting 20+mpg. It's an absolute fact that whatever diesel truck you have, Ford, Dodge, GM, you MUST tell everyone you are getting 20+mpg at 80mph. It is acceptable to make statements like, "I get 18mpg towing my 30,000 pound box trailer/RV/Gooseneck/etc. as long as I keep it under about 85mph."

If you keep making honest statements about your diesel truck's fuel mileage The Diesel Mafia is going to have to take action.

 

[Ricko1966]

@mibars My 88 burb got about 17 on the highway @Vbb199 his burb got really good milage. I honestly think tbi burbs get better mpg than squarebody pickups and I think part of is the shape. Someone will correct me but I think the burb has less wind turbulence on it'd advantage. IDK

 

[Grit dog]

Look, I am usually aligned with you but you have definitely crossed a line here. You cannot be telling people that your Cummins diesel isn't getting 20+mpg. It's an absolute fact that whatever diesel truck you have, Ford, Dodge, GM, you MUST tell everyone you are getting 20+mpg at 80mph. It is acceptable to make statements like, "I get 18mpg towing my 30,000 pound box trailer/RV/Gooseneck/etc. as long as I keep it under about 85mph."

If you keep making honest statements about your diesel truck's fuel mileage The Diesel Mafia is going to have to take action.

Lol. That’s hilarious. I see you’ve met the guys who get 25mpg doing 80mph in their 1 ton (insert their favorite brand of diesel) and it drops to 15-17 mpg towing their 5ver over Donner Pass….
Well how aboot this. My new 3.0 Duramax half ton truck gets an honest 23mpg so far driving it like a rental car! Actual true story. But there’s guys here at work who “get 30mpg.” Lol.

 

[gmbellew]

driving at 70mph+ is what kills mileage the most on a squarebody. drive down the interstate at 60mph, if you can stand it, and your mileage will be significantly better.

 

[Hogger]

For what it's worth, (remember the original question) I got about 17 mpg on the highway Tucson to Phoenix trying hard to stay at about 65. Mine is a 84 K20 with a fresh HT383. I thought the gas gage was kaput cause you know how they are. This was with the restrictive original cast exhaust manifolds. Haven't made it to the highway yet to look for improvement with the new headers/dual exhaust. Sure feels better around town though!

 

[Ricko1966]

Lol. That’s hilarious. I see you’ve met the guys who get 25mpg doing 80mph in their 1 ton (insert their favorite brand of diesel) and it drops to 15-17 mpg towing their 5ver over Donner Pass….
Well how aboot this. My new 3.0 Duramax half ton truck gets an honest 23mpg so far driving it like a rental car! Actual true story. But there’s guys here at work who “get 30mpg.” Lol.

I actually have been thinking about this and redfishs comments on the diesel mpg. Especially since I drove it home from Columbia,MO. To Linn County Kansas. Filled up in Columbia,drove to Lee's Summit then home. Figured the milage 25mpg. 6.2 4l80e. Did the math again,told a buddy said I can't believe this he ran the numbers said yea that's it. But thinking this over real hard odometer,and 2 different gas pumps. In reality I don't know exactly how much I burned just how much it took to top off. Milage IDK what ever the ODO says. So now I have no idea,and I hate you guys. Thanks