Nobody warned me about the MPGs on these square bodies!

[gmbellew]

That 'Burban of yours has TBI, fuel injection, and sits way down lower too. What axle ratio is in the Suburban, 3.42?? That's comparing apples to grapefruit.

i have 3.73 with a 2.5in lift. OP is also fuel injected, 700r4, and 33in tires. but he has 4.10, also guessing a similar lift, could be a lil higher. lots of similarities, but a few differences.

the burb has a lot more metal and glass weighing it down.

another difference is 396 vs 350.

also his sniper might need some tuning to improve efficiency.

not exactly "apples to apples" but could be like granny Smith vs honey crisp with some of the differences canceling each other out.

 

[Camar068]

I stopped thinking about it. I'm getting ~12 mpg on a non-tuned LS stock ride height, 3.73 with 32" tires. Daily driver and any running within 75 miles.

 

[Matt69olds]

No offense but I’d have to see that hand calculated in person. I’ve got an 06 2500 4wd Megacab w/ 6spd & 3.73’s, I’ve never gotten better than 16.5 (hand calculated since new). My overhead instant average always displays approx 6~7 mpg’s high.

Same here. My 06 2500 4x4 mega cab auto with 3.73 will occasionally hit 18 mpg. The best I have EVER gotten was 608 miles on a tank. The tuner I have in the pcm does help, both power and economy.

On a more humorous note, the overhead console has never been very accurate, with the tuner loaded it’s even more of a joke. The only way that truck will get 34 mpg (which it regularly shows!) os being towed.

 

[Ricko1966]

i have 3.73 with a 2.5in lift. OP is also fuel injected, 700r4, and 33in tires. but he has 4.10, also guessing a similar lift, could be a lil higher. lots of similarities, but a few differences.

the burb has a lot more metal and glass weighing it down.

another difference is 396 vs 350.

also his sniper might need some tuning to improve efficiency.

not exactly "apples to apples" but could be like granny Smith vs honey crisp with some of the differences canceling each other out.

I think it's the camshaft profile of his 396 .638 .622, 251 259 @.050 and Sniper is TBI also,it's just 4bbl tbi so tuned right that's not a game changer unless his foots in it constantly.

 

[Ricko1966]

I think it's the camshaft profile of his 396 .638 .622, 251 259 @.050 and Sniper is TBI also,it's just 4bbl tbi so tuned right that's not a game changer unless his foots in it constantly.

I just had to laugh, @gmbellew let me guess, your camshaft profile is around .400 lift 200 duration @.050 ? I think I have solved the mystery. We are comparing apples to much bigger apples.

That didn't sound right. I didn't laugh @gmbellew . I laughed and then was asking his camshaft profile

 

[JBswth]

Today marks the second time my square body has run out of gas on me.

In fairness, it's my own fault. When I bought the truck the dual fuel tanks didn't work (only the main tank worked) and the fuel gauge was in no way whatsoever accurate. My next project is fixing the tanks (as anyone knows who has been following my threads on this forum). Still, I figured I've got 16 gallons in the main tank and that should be enough to get me to and from since I don't do much driving.

Oh boy was I wrong! Today my square body ran out of gas on me for the second time and left me stranded on the side of the road. I was shaking my head thinking I just filled the main tank a few weeks ago and I'll be damned if I've driven more than 50 miles (if that), unless I am forgetting something.

I had the thing towed home, put more gas in it, and it fired right up.

I know, stupid me. The fuel gauge doesn't work so how could I ever really know for sure? Still, my main driver which is a 2019 F150 3.5 Ecoboost gets much better (though not great) MPG. I figured that the K10 would get much worse MPG than the F150, but I had no idea it would be this much worse!

I suppose it doesn't help that I've got a 500HP Blueprint Engines 396 stroker in there with a Holley Sniper EFI setup. No idea what sort of MPG it's getting but after today I'm convinced I'm getting 8 MPG at best.

Anyways, I didn't buy this thing for the MPG (obviously) but I had no idea this thing would suck gas the way it does! Talk about a wakeup call

The cold weather and snow is about to set in here in rural Wyoming so it's time to get started on the fuel tank project!

Aggressively cammed engines simply do not get good mileage. Just a fact of life. If you want a big engine that DOES get relatively good mileage, you need to go milder - MUCH milder. A 396 cube engine that makes, say, about 200 horsepower will get surprisingly good mileage, and, being 396 cubic inches, will make enough torque off the line to launch you pretty smartly as well.

J. B.

 

[DoubleDingo]

Did the math for the C10 I'm at 298mi on 50 gallons of 93 at $4 per gallon puts me at 5.96 miles per gallon and about $200 thus far. Pretty much right in the middle of my 5-7 estimate.

$200 in the ranger of 87 would be 67 gallons and about 1200 miles.

It's the fin, it forces your right foot down on the skinny pedal

 

[DoubleDingo]

I think it's the camshaft profile of his 396 .638 .622, 251 259 @.050 and Sniper is TBI also,it's just 4bbl tbi so tuned right that's not a game changer unless his foots in it constantly.

He said good sounding exhaust and a heavy foot, so there's that

 

[xm20k]

It's the fin, it forces your right foot down on the skinny pedal

Just too tempting. I finished up wiring the line lock button to the relay box yesterday and of course you have to test your work.

 

[DoubleDingo]

Just too tempting. I finished up wiring the line lock button to the relay box yesterday and of course you have to test your work.

It sounds too good making loud vroom vroom sounds out the tailpipes

 

[Grit dog]

My ‘85 C10 (q jet equipped 350, 350C transmission, and 3:08 rear end) can get 12ish mpg when I drive in a tame, civilized manner. If I stuck to highway only, I could probably get a consistent 13-14 mpg.

Very similar to my 77 C10 350/350/3.08s.

 

[Grit dog]

I stopped thinking about it. I'm getting ~12 mpg on a non-tuned LS stock ride height, 3.73 with 32" tires. Daily driver and any running within 75 miles.

About the same as a 5.3 gmt 800 4x4 pickup or suv. I think the ‘Hoes we’re in the 13s

 

[Terlingueno]

In the 31 years I have owned my Suburban, my Fed.gov job duty stations were in some of the most isolated places in the US so lots of highway miles. Little things like 100-250 mile round trips to get groceries, truck parts, doctor visits, family visits, airports, etc all highway miles. My duty stations were walking distance from quarters to my station, so no driving involved. Any driving on duty or to training were with a fed.gov vehicle. The vast majority of my miles driven are still highway miles, since I still live on the edge of the middle of nowhere, my doctor is 210 miles round trip, "town" is 160 miles round trip, closest airport is 225 miles away, medical specialists, same. The only "city" driving I do is when I reach "town" and then it is just for an hour or two. Then it's back on the highway to get home, at 55 mph...

 

[Dixie Pride]

When i bought my 1985 3/4 ton manual ,350 engine new the sticker said 15-17 and that is what it got. It get's 6 mpg now built up with 44" super swampers.I de-smogged it cause i got farm tags on it and it did not make much difference.It is my Sunday driver now, wax it, and drive the back roads sure fells good to still be driving something you ordered 41 yrs. ago.

 

[RavenLord]

When I installed the FITech EFI system on my 79, I had hoped to maybe get a bit better mileage from the truck. Noope. It got 11-12 from the start and that's about what it does now.
Drivability did improve dramatically so it was worth the effort, but it will never pay for itself at the pump.