Fuel efficiency...what MPG do you get?
 

So, a few questions about fuel economy and the 73-87 chevy pickup.

What are you running (engine, tranny, gears, mods) and what are you getting for MPG?

How do you squeeze every last mile out of a tank?

If you could build a truck from the ground up what do you think would be the most fuel efficient setup?

(i have no clue what my MPG is at the moment, my speedo doesn't work right now...but it doesn't seem to be as bad as i thought it would be)

Re: Fuel efficiency...what MPG do you get?
 

-383ci stroker (~450hp/475ft lbs)
-M21 4 speed
-3.42 gears, 28" tires

14-15 MPG (50/50 city/highway)

If I were building a truck from the ground up and wanted max fuel efficiency, I'd do a LS1/T56 swap.:)

Re: Fuel efficiency...what MPG do you get?
 

well i have a 305 with a th350 recently rebuilt unknown gears and my truck gets about 5-7 mph in NYC the carb seems to be off so im going to go back to a non edelbrock carb

Re: Fuel efficiency...what MPG do you get?
 

the rig- 86 C-10
350 V8, TH350 transmission, an old tired rochester carb
I drive about 80% city and 20% highway, when I do drive it
It has stock 3:08 rear gears, and for some reason it has 31x10.5x15 tires on a 2wd
The only mods I have are royal purple engine oil, no cat converter, flowmaster muffler, and a K&N air filter.
Last time I checked, I got 10mpg. I think it's due to the ineffiency of the carb, and the way I drive it.

Re: Fuel efficiency...what MPG do you get?
 

1984 SWB
383 - around 400hp
Manual Valvebody TH400
2900 stall converter
3.73 gearsl/Detroit Locker
275-60-15's

8-10 mpg.

If all I wanted was fuel economy, I would do a 283 or 302 with a two-barrel Holley, 200R4, 3.08's, should be good for over 20 mpg on the highway...

Re: Fuel efficiency...what MPG do you get?
 

350 300hp edlebroc 650
th350
373 gears

275/60-15 tire

6 to 7 mpg I would get about 12 if I keep my foot out of it

Re: Fuel efficiency...what MPG do you get?
 

I averaged 15mpg on my last tank.
92 carbd 350 with a th350 and 3:08 rear. I drive it like an old man lol

Re: Fuel efficiency...what MPG do you get?
 

8 if Im lucky, on a downhill slope, and the wind is on my tail end...

I pass everything BUT a gas station...

Re: Fuel efficiency...what MPG do you get?
 

1981 K10 305/350 all stock. No muffler, VERY low gears (5.56 or lower), 235/75R15's.

It's about 400-500 pounds lighter than stock due to the rust.

I get between 6-10mpg on it depending on weather. I live out on the prairie so I get the full brunt of ANY wind flat in my face. Generally when I'm late getting to work so I've got my foot in it.

BTW, a block from my house I'm doing 65mph for the 10 miles to work, so pretty much all my driving is highway.

Re: Fuel efficiency...what MPG do you get?
 

88 K5 blazer, stock 350 tbi, 700r4 tranny, unknown rear gears.
14 mpg hwy, 10 or 11 in town


75 C-10. 454, th350 - also unknown rear gears -- might get 9 or 10 at best

(i dont drive 'em much anymore, but the 14 hwy my k5 gets is not much worse than my new 5.4l F150)

Re: Fuel efficiency...what MPG do you get?
 

11 MPG but i need some work on the carb.

Re: Fuel efficiency...what MPG do you get?
 

Re: Fuel efficiency...what MPG do you get?
 

89 454 TBI Burban, just did a 300 mile trip and got a solid 10 MPG thinking of putting a TB spacer, injector spacer and an adjustable fuel pressure reg on , supposed to help mileage.

Re: Fuel efficiency...what MPG do you get?
 

87 Silverado swb 2wd
engine: high mileage 305 TBI
transmission: 700r4
tires: 265/75/15
gear ratio: not sure, but probably pretty high highway gears

I'm only getting about 12 mpg driving pretty easily. I'm a bit dissapointed since I thought the tbi would get a bit better mileage but it does have some pretty big tires, which I plan on dropping to a 255/70/15, and the motor is a bit tired.

Re: Fuel efficiency...what MPG do you get?
 

Last time I posted BS started walking because some people don't think it's possible.

old stock 305 - 18 MPG at 70 MPG. Drove straight though the tanks too. Long 1000 mile trips.
305 - 13 MPG in the city. Lots of work on engine and truck.

ZZ4 - 13 MPG in the city so far. I can't seem to keep my foot out of it. 2500 stall and higher than normal shift points until the tranny is well broken in. I can't wait for a long trip out of town. I'm really curious on what it can pull off. Planning a trip in May. I'll drive through full tanks and calculate.

Re: Fuel efficiency...what MPG do you get?
 

400- preformer II intake, 650 thunder carb, mild ( i mean mild RV cam crane i think), HEI, serp belt, hooker long tubes, flowmaster 50's with stock Y pipe and cat.
TH350C with Hurst shift kit. TQ is unknown stall
Stock open 10 bolt rear with the shatty 273's

On the high way i get about 12-15 MPG

Re: Fuel efficiency...what MPG do you get?
 

After seeing and reading what I see here I guess I'm pretty lucky. I can understand Bob (Rusty) only getting 5 to 7 MPG in NYC on account it takes 3 days to cover that much ground, but the rest of you guys at 10 to 12?? Mine is an 84 K20 all stock. The engine has 465,000 miles on it and all I have ever done to it is rebuild the Q jet 4 times and do a valve job at 250,000. I did swap out the oil pan for a 5 qt and use the tall GM oil filters and really good oil (Mobile 1) Truck does ALL highway miles. Specs are 350 cid "M" eng 285 HP, Q jet carb, HD4 speed manual, 3:73 gears and tires are 235-85-R16 and a real light right foot. 15 to 17 MPG loaded or empty. jim 33 year GM mechanic

Re: Fuel efficiency...what MPG do you get?
 

Bout 12 with a 454, t400 combo 4.56 gears and 33 x 12.5 tyres running straight propane, average driving conditions, hope to improve that with the addition of the gear vendors I have

Re: Fuel efficiency...what MPG do you get?
 

I really need to get my speedo working. I feel like im getting over 12 but have no clue. i drive 12 miles to work each way, and i have made the trip 3 times plus errons and stuff over the weekend and im still on tank one with 1/4 left. So....about 100 miles on 12 gallons (16 gallons/.75)...12mpg?

PS. I cruz, no lead foot here, and the drive is on US 19 so the average speed is 45-60mph.

Re: Fuel efficiency...what MPG do you get?
 

1980 3/4 ton, stock carbed 350 bored .030 over, turbo 350, 3.73 gear, I average 11 mpg no matter city or hwy, how fast or if I am pulling my camper I can always count on right around 11.

Re: Fuel efficiency...what MPG do you get?
 

1975 C20 long bed with clamp shelf.
Engine 350 with a mild RV cam, TBI and custom real time tuning (highway lean cruise not enabled, yet)
Transmission 700R4 with stock converter (about 1400 RPM)
Rear end 4:10 with 33 inch tires

Highway about 17 mpg, city 13 mpg. Previously, before converting to EFI with Q-Jet i was getting 12 mpg on highway and 9 in city.

//RF

Re: Fuel efficiency...what MPG do you get?
 

engine: reman 350 vortec w/headers, performer 600 cfm
tranny: reman TH350
rear: no idea
tires: 255/70-15

I get 15 with a pretty long freeway drive to work.

Re: Fuel efficiency...what MPG do you get?
 

I get around 15mpg or so going 75mph...

78 c20, bone stock original 350, th400, 3.73 gears 265/75/16 tires.

Re: Fuel efficiency...what MPG do you get?
 

82 Chevy c10- 350, th350, 3.08s and 32" tires.. about 8 city and not sure on highway... the high gears and big tires killed the around town mileage but the highway mileage was pretty good unless there was much of a head wind. With that tire/gear compo the torque just wasnt there.

87 GMC 2wd- tbi 305, 700r4, 3.08s and 235/75r15... about 16 around town. Which I thought was pretty good since my wife's 97 s10 blazer 4x4 got 16 as well.

Re: Fuel efficiency...what MPG do you get?
 

On the '86 crewcab, I don't wanna know! It's an off the road only truck at the moment.

'84 Chevy flatbed dually with around 60,000 original miles
454/SM465/4.10 D70 cab-chassis rear
I figure about what, 6? in town and MAYBE 10-11 highway? I hadn't driven it on the highway long enough to check. About a month ago I installed a high performance cap/rotor, then a set of Bosch 8MM wires and R45TS Delco plugs gapped at .045. Monday the timing(4 degrees before TDC) and carb were adjusted and she's running good!

Re: Fuel efficiency...what MPG do you get?
 

I had an 83 short bed with a 355 vortec head engine, 700r4 tranny, and a 12 bolt with 3.08 gear with 275/60/15 tires and got 22 most of the time on the interstate. I pulled a full trailer with an 88 camaro on it and still got 17 going from birmingham to ft. walton beach.

Re: Fuel efficiency...what MPG do you get?
 

I have a stock 305 tbi with a 700r4 and 2.73 gears. As long as I keep out of overdrive, I can get 17-18 mpg. I drive back and forth to work averaging 55 mph.

Re: Fuel efficiency...what MPG do you get?
 

Haha, I have a '78 K20, 350/400/np203 and I'm pretty sure 3:73's getting about 6.5 mpg. not sure the actual mileage, but thats what it feels like

Re: Fuel efficiency...what MPG do you get?
 

78 c10
76 400
373 rear
th400
I get smiles per gallon

Re: Fuel efficiency...what MPG do you get?
 

78 K10. Nice weather and hubs unlocked I get 10 in town and 12 on the highway.

Re: Fuel efficiency...what MPG do you get?
 

1974 Chevrolet K20.
350 has head work consisting of a valve job, port and polish both sides,matching intake, stock cast intake, and a 600 edelbrock mechanical secondaries. Has full length flowtech headers into a 2.5" straight true duels exhaust.
SM465... WITH 4.10's and 39.5" Baja belted atz's I get 18 highway mpg at 75. 18 at 55 as well. Now it get 1 tank to about a year as the rear end is out lol.

Re: Fuel efficiency...what MPG do you get?
 

'83 K30, warmed-up 350 (cam, headers, AL intake, modified Qjet, stock heads and compression) , 4.56 gears, 205,SM465, 305/75/R-16 on 16x10 Alcoas = 12 mpg/HiWay with a ton in the bed.
'90 stock V3500 3+3, 454 tbi, 4.10's, th400 = 8 to 9 mpg combined. (55 only on the interstate or the gas gauge moves much faster)

For a comparison ; stock '9x something G20 van, 6.2 NA diesel, 3.08 gears and a 4L60 = 18 mpg combined. Fully loaded all the time.

edit; almost forgot. 2000 3500HD, TD 6.5 , NV 4500, 4.63 gears , 10,200lbs - bed empty/toolboxes full, 15 mpg combined/mostly city - with one hour drive @ 55. Checked two tanks with about the same driving 15 mpg both times, 10 mpg if you don't short-shift the gears and just let it windup like a gas engine.

Re: Fuel efficiency...what MPG do you get?
 

I should have given more data:

78 K10. Nice weather and hubs unlocked I get 10 in town and 12 on the highway.

350, 12-300-4 cam, Edelbrock 1406 on dual-plane air-gap manifold, Hooker headers, H-pipe, TH350, 3.73:1 on BFG 31" tires.

Re: Fuel efficiency...what MPG do you get?
 

86 c20 with 260hp crate with 63k on it with one bad ticking lifter and one burnt vavle sm 465 3.42 gears with stock q jet 14 where i live with my heavy right foot. 21-23 down the highway depending on ebrake draging or how flat the highway is. at 75 i get 16-17 all the time. truck rolls around at 5600 with me in it plus the tools i have in it at all times. i dont know why but she does good on fuel even my k30 got me 18 at 60 with 6.2 and 4.10 and the c30 i have is 10 with 454 465 and 4.10. all my trucks are stock drive trains only thing i have done to the 86 is turn the timing up and tune the carb once in the 8 years i have had it and it is the origanal to the truck as far as i know.

Re: Fuel efficiency...what MPG do you get?
 

1973 C20, 350 engine with a little headwork, Comp Cams 252H, Edelbrock Performer intake manifold, Edelbrock 750cfm carb (too big), non-air manifolds, full exhaust - it's a truck engine, but a lot better than stock. TH350, 4.11s, 245/70-17 tires, tow mirrors, utility bed.

I tend to see around 10. Hoping to increase that by at least 50% with a 4.8 or 5.3 swap backed by a 4L80E... I think the engine spinning pretty fast really hurts freeway mileage, so overdrive should help a lot.

Re: Fuel efficiency...what MPG do you get?
 

Surprised no one has jumped in with their diesel mileage.

Re: Fuel efficiency...what MPG do you get?
 

Glad someone brought this thread back to life. I was wondering what the stock engines were getting. Thanks

Re: Fuel efficiency...what MPG do you get?
 

See my post up 4 from you. Have two diesels listed.

Re: Fuel efficiency...what MPG do you get?
 

23mpg. See my sig. 1/3 country, 1/3 highway, 1/3 city. Fully loaded 87 R10 , 6.2 diesel, 7900R4, 3.08's, stock size tires.

Re: Fuel efficiency...what MPG do you get?
 

I have an 84 K20, 350, quad with a 465 trans and 3.08 gears. IF I keep my foot out of it I can get 17 to 18 MPG pulling a 7000 pound trailer on the highway. Around town I get about 10 or so. Truck is all stock right down to tire size. I think the tires are 185-75-R16 and I run them at full pressure of 85 PSI.