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Holy sh*t! 14mpg!

Cntymnty77

Cntymnty77

1/2 ton status
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Sep 6, 2016
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Location
Missouri
Just got back in town from a work conference that was 146 miles away and I decided to roll the dice and take the Blazer. I loaded up all tools I thought I might need and headed out Sunday night. I made it down to the lake of the ozarks and quickly added up my mileage and wow! 14.16 mpg! I thought I did my math wrong but I did it again and then had another guy I was with do it and it was right! I would have figured maybe 7-8 mpg, especially with all the hills I had to climb at highway speed. I also thought I’d have to make a run to a parts store but nope! I was just curious what everyone else was getting on here?
 
My stock 87 got 12.5 around town consistently. 15.1 on the open road once at 65mph. The jimmy? No idea, not what I built it for. I fill it when it gets to 1/2 a tank. No odometer.
 
My 88 TBI-350 4x4 burb got 14.8 on the only real trip it ever went on. That was OD, 33's, 3.73s, and about 65mph. never checked it again after that really.
 
Just checked Ethel and with 100+ degrees on Ca fuel with a 40mph headwind and the ac cranked got worst ever 13.2 doin 65-70.. best ever was 19.7 no wind in the winter.
 
My K10 stepside on 35"s got 15 mpg all highway around 75mph on my last trip to Silverlake. The OD on the NV4500 and a leaned out cruise on the EZ EFI got me there. Pretty damn good for what it is. Normally though it's 11-13mpg beating on it around town. I don't get far in my single 16 gal saddle tank :doah:
 
I daily drive either smokey the crew cab , or the burb . both trucks are setup identically.

6.5 , banks turbo, Th400/205 , 4.10's and 35" rubber .

If I hold 60 (indicated ) I can maintain 20mpg in the crew cab and 18 with the burb ( burb has a Lund Visor and it's overall shape I think kills mileage even though it's lighter ). If I push them any faster mileage tanks quickly. 2-3 psi of boost seems to be the sweet spot.

Best tank ever was 21 mpg with the crew cab on a long trip from Anchorage to Fairbanks.

I have a 4L80E for smokey and a nv4500 for the burb, but not really sure that will improve much . I think it's the amount of air they push combined with being in the sweet spot of the power band.
 
With the gas we have today your lucky to get much over 12 mpg with any older V8 in a heavy full sized vehicle..

Back in the mid 80's I used my 72 K5 to commute to work 65 miles each way,and I could usually get 15 mpg with it..350 engine,3:08 gears,and it got the same mileage when it had a TH350,and after I converted it to a SM465..maybe slightly better with the automatic,as it would lug pretty badly around town,it was hilly where I worked..

I had a '74 C-10 with a 454/TH400 and 3:08's that got the same mileage with the stock Q-jet--I put a Holley 450 CFM Economaster carb on it and it went up to 17 mpg on highway trips,about 12 around town..

My '81 G-10 van had a 250 six in it with 3:08's and a TH350 lockup converter,that thing got about the same,16 mpg,though when I took it to Nashville in 1992 for some reason it got closer to 20,even going thru PA in the Poconos where it struggled to maintain 50 mph in second gear up the mountains..
I guess coasting down the other side made up for it..also this was before they "oxogenated" the fuel and added ethanol..

After I put a 307 V8 in the van,the MPG dropped to about 15 mpg ,I also put a 2:73 rear end in it after the 3:08 developed a hogged out diff case where the side gear rides..I think that smothered the 307,it's best power/torque band is higher in the rpm range..

I had a '67 Impala with a 283 and a Powerglide ,3:08's ,that got 18+ mpg consistently,even though it was tired and smoked some..

I had an '80 El-Camino with a 267 V8 and a TH350,with 2:56 posi in it--that thing cruised at 80 silently like it had an electric motor,and got over 20 mpg often..a '82 GMC Cabbalero I had with a 229 V-6 didn't even do as well..

My 6.2 in my '82 K2500 never got much more than 16 mpg either,no matter what I do with it..

The "worst" vehicle I had for fuel consumption was the '69 GTO,it only got 12 mpg regardless of city or highway,but I drove it like I stole it most of the time too..the 400 engine & TH400 were thirsty,it also had 4:10 gears..I still used it to commute to work as lot though,it was more fun and more comfortable to use on longer trips..
 
When I bought my '85 K10 Suburban with a 6.2,it had a nearly full tank,and I think it holds 40 gallons..

I have started it up and let it run at least 48 hours since I got it (not all at once!) ,sitting in the yard,to keep it from rusting up and seizing..every few months I put 2 batteries in it and get it fired up and let it run,move it around some,so the brakes wont rust up..

It still has over 1/8th of a tank,almost 10 years later...I imagine its pretty stale by now,it starts harder each time and it doesn't have the typical smell of diesel exhaust..
 
I get 16.5 under favorable conditions...60-65mph, fairly flat ground, no stopping and starting. It's a bit better than that because the speedometer/odometer are a bit slow (compared with GPS), but it's not enough to make the numbers appreciably better.

Stop/start/hills, 10mpg is the norm.

L31 long block, tpi, sm465, 205 (now 241 but not tested mpg), 3.42 14sf, 33" bfg at ko's.
 
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