78 K5 Gas Mileage

[cstew47]

Never seen it that bad

That was why I posted. I think I need to do some work.

 

[RecklessWOT]

I just noticed on your profile that you have a V10 burb? What engine is that? A viper?

Hah that would be cool. No it's just a regular 350TBI. 87 was a weird year, a 1987 V10 is same thing as a K10, just a 1/2 ton 4x4 (and the R10 was the same as a C10, 1/2 ton 2wd, and as you can guess, the 3/4 tons were V20 or a 2wd 1 ton crew cab would have been R30, etc), they just changed the naming scheme in 1987 to get ready for the GMT400 trucks that came out in 1988 which took over the C/K naming scheme. V was 4wd and R was 2wd. The pickups became C/K1500 in 1988 while the Suburbans and crew cabs stayed R/V10,20,30 for 87-88, then in 89-90 they became R/V1500, 2500, 3500. It's a weird thing. In real life when people ask what kind of truck I have I just tell them it's a K10 Suburban, but here just for the sake of being correct around a bunch of guys who know all the technicalities I listed it as a V10, which it technically is. Hah, you should hear the guys at the parts stores get confused when I call for parts. "they didn't make a V10 in 1987, Bud. You've either got a regular 350 or a diesel but they're both V8s..."

 

[RecklessWOT]

That was why I posted. I think I need to do some work.

It could probably be a hair better, but driving a lifted truck with 4.56s and a 383 through the hilly curvy slower speed roads of Columbia I wouldn't expect you to get as good of gas mileage as a guy who drives a less modified truck with a 350 in it. 8mpg is more than 6mpg, but not by leaps and bounds. It's not like you're getting 4mpg and he's getting 12. Honestly I am not shocked by the 6mpg figure. You could probably tune it up some, but I wouldn't lose any sleep over it

 

[ali_c20]

You live in Austria? Gas is pretty pricey there. Filling the tank must be an event. Here in Colombia premium is about $4,00. I have to get a second mortgage every time I fill it.

Yes, filling up my 31 gallons gas tank when it's nearly empty costs a small fortune. At the moment the gallon of premium is ~ 6.50$ and rising daily. The prices will go up as hell when the government will introduce the CO2 taxes on fuel for saving the planet. I need to hoard gas before that happens.

 

[Bextreme04]

It could probably be a hair better, but driving a lifted truck with 4.56s and a 383 through the hilly curvy slower speed roads of Columbia I wouldn't expect you to get as good of gas mileage as a guy who drives a less modified truck with a 350 in it. 8mpg is more than 6mpg, but not by leaps and bounds. It's not like you're getting 4mpg and he's getting 12. Honestly I am not shocked by the 6mpg figure. You could probably tune it up some, but I wouldn't lose any sleep over it

Getting 6mpg rather than 8mpg is a 25% decrease in fuel mileage.... and I get BETTER mileage when I'm keeping it below 55-60mph, not worse. Now if its stop and go, I could see that...

Either way, I bet if he had a wideband 02 sensor in there he would see a huge over fueling condition. It might be necessary to prevent detonation depending on how hot the engine is and how poor the fuel quality is, but I doubt it.

 

[Rusty Nail]

Sounds about right to me.

 

[82sbshortbed]

Hilly winding roads would be perfect for a motorcycle. That would be fun.

 

[Rusty Nail]

I'd get a little one you could put in the back of your truck..THAT would be fun!

 

[GMFORLIFE]

Turn this into a positive.
Invest in a tremec overdrive transmission.
Shouldn't take long to recoup cost at $3 per gallon.

 

[GMFORLIFE]

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[GMFORLIFE]

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[Rusty Nail]

That 81 grille though!
Nice to see dude ditch the black wheel...it looks a lot better now.

Even in stock form these trucks got terrible mileage, once you modify them the number only goes down more

Haha! That was funny...once you modify it....lmao yep...never hear about a 2bbl conversion. Bet they're like hen's teeth in 2021.

 

[77 K20]

I saw this post last week and made me curious. Last weekend I went on a trail ride with my truck.

It was 158 miles round trip. Temp was 80 degrees in the morning and peaked out at 90 degrees in the evening.

26 of those miles were on rough dirt trails with hill climbs and descents. Maximum speed might have been 10 mph at one point. Most of the time just off of idle.

74 miles of it was on a small highway with the speed limit of 50 and some parts 60.

The remaining 58 miles was at 65 mph.

This is on a 1977 K20 truck with the GM HT383, Edelbrock TBI fuel injection, 37" tires, 4.10 gears, and am currently running the NP203 full time transfer case.

I used up 13.7 gallons. Thats 11.5 mpg.

I don't trust my odometer much. It is off a bit. So I used google maps to trace every road I went on. Highway driving was pretty flat... just some small hills here and there.

I drove it nice and easy- as my used full time transfer case is making bad chain noises at me.

 

[cstew47]

Turn this into a positive.
Invest in a tremec overdrive transmission.
Shouldn't take long to recoup cost at $3 per gallon.

I already have a 4L60. Unfortunately the roads here don't allow me to get into O/D often.

 

[cstew47]

Yes, filling up my 31 gallons gas tank when it's nearly empty costs a small fortune. At the moment the gallon of premium is ~ 6.50$ and rising daily. The prices will go up as hell when the government will introduce the CO2 taxes on fuel for saving the planet. I need to hoard gas before that happens.

At least the food is good there.