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What IS gas mileage?

10K views 91 replies 29 participants last post by  MARTINSR 
#1 ·
Built lots of hot rods and know how to make power BUT now I'm building a really light weight 83 Chevy 1/2 ton 4x4 to use as a shop truck for my upholstery business. I am looking to build it for great gas milage, mostly around town. We need 4wd in Iowa.
I am looking for engine suggestions. I have a stock 350 with ramhorn exhaust and an edelbrock 600 right now. I also have a performer intake and a quadrajet I'm thinking of using. Weight will be about -1000 pounds. TH350 2.56 gears. Part time 4wd with lockouts. Runs great and I got it CHEAP.
LOw budget but if I can get better milage it may pay to make major mods. My 90 efi chevy SUCKS gas.
 
#2 ·
Forget the Performer intake and see if you can find an Edelbrock Streetmaster(check ebay) see pic below.Crower still has cams made for low end and fuel mileage visit their website.Your quadrajet is 750 CFM if you are wanting mileage Holley made a Carb called the Economaster 450CFM that was a quadajet replacement, I have a source for those (send pm) look for headers with 1 1/2" primaries for more mileage and low end torque.
 

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#4 ·
ap72 said:
If your current engine is in good tune, then leave the thing alone, modifications for mileage usually require a LONG pay back period, sometimes longer than the life of the engine/vehicle.
I disagree with a blanket statement like that, the cost isn't going to be that drastic at all, IMO, any mods you can make for a reasonable investment to improve economy, are well worth the effort.
 
#6 ·
ap72 said:
If your current engine is in good tune, then leave the thing alone, modifications for mileage usually require a LONG pay back period, sometimes longer than the life of the engine/vehicle.
I did the math and this is what I came up with.

save a gallon a day @ $2.75 a gallon (soon to go over 3 bucks)X 365 days = $1003.75. Keep his budget under that and he can get payback in 1 yr.
Would that be considered a long payback period, or am I missing something?
 
#7 ·
If you want to save money both in purchase price AND mileage, get the 4x4 idea out of your head. I grew up in PA and ONT and rarely needed 4x4. A good set of snow tires is all you need.

My winter car in Ontario was an open-axle Caprice and if it was bad enough that I couldn't go out there was nothing open anyway.

"Need" and "4x4" are words you use for offroading IMO. I had a 4x4 chevy in PA and in 230k miles I think I used 4x4 on the road twice. I needed it for getting to the cabin which was 4 miles back in the woods over really nasty terrain.

Otherwise, the Qjet will return the best mileage you can expect. Don't be tempted to trade "up" for a TBI. Your mileage might drop considerably. The as-delivered curb weight on that truck is probably north of 4500 lbs so don't expect miracles. Be smart in your tire selection. 235mm is all you need, and don't use big knobby tread. Buy a set of H/T or passenger tires and one pair of snow tires in the back. Also skip the HD tires like E-range. A good P-metric or LT truck tire in C range is all you need and the drastically reduced weight will help overcome the gas you waste getting up to speed. It will also reduce rolling resistance.

A good mileage combo would be to use the TBI cam in something like a 305 or drop in a stock 4.3V6.
 
#8 ·
sqzbox said:
I did the math and this is what I came up with.

save a gallon a day @ $2.75 a gallon (soon to go over 3 bucks)X 365 days = $1003.75. Keep his budget under that and he can get payback in 1 yr.
Would that be considered a long payback period, or am I missing something?
Your math is right, but your assumption isn't realistic. Let's say we take his MPG from 15 to 17. Now let's say he drives it 50 miles per day. He's only saving about 1/3 gal a day.

So, he's saving about $0.88 a day. If he spends $1000 on upgrades and uses the truck 300 days a year (6 days a week minus holidays) that means a savings of $264 per year. It would take nearly 4 years to recover his costs on fuel.
 
#9 ·
gas mileage, gas mileage, gas mileage the dream. To clarify my position I do not care. I like hotrods and don't think the words, gas mileage and Hotrods fit in the same statement an, oxy moron.

But I can use these words in a sentence.

The best gas mileage a hotrod can get is parked what fun is that ? in a word none.

The mod I think could get that gas mileage better is on the end of the right leg, that foot. Driving is like a chess game planing your maneuvers to get around. The drivers that you see driving up on the lights quick stop and then green stomp that peddle .......... the same ones crying about gas mileage .

Feathering the throttle, timing the red lights so that you never come to a complete stop will buy you miles. It is a game bikers play, the idea is not to put your foot to the ground once you are in the wind.

Inertia keep it rolling with the least amount of energy.

Want mileage, buy a bean car the smaller the better want mileage dump the large car/truck for light weight small engine, its physics and oh yes keep to the right please, stay out of the fast lane.
 
#14 ·
RAYFIN said:
Built lots of hot rods and know how to make power BUT now I'm building a really light weight 83 Chevy 1/2 ton 4x4 to use as a shop truck for my upholstery business. I am looking to build it for great gas milage, mostly around town. We need 4wd in Iowa.
I am looking for engine suggestions. I have a stock 350 with ramhorn exhaust and an edelbrock 600 right now. I also have a performer intake and a quadrajet I'm thinking of using. Weight will be about -1000 pounds. TH350 2.56 gears. Part time 4wd with lockouts. Runs great and I got it CHEAP.
LOw budget but if I can get better milage it may pay to make major mods. My 90 efi chevy SUCKS gas.
Sounds like there's an issue with your '90, any TBI I've ever owned got great mileage. Sure you can't make it work? That said, get rid of the Edelbrock carb and put a "good" Q-Jet on a stock iron Q-Jet intake on the '83. Run tall skinny tires and stay conservative on tread design. The more aggressive the tread the worse your mileage will be. Make sure it's well tuned and mechanically sound. Make sure the thermostat is good and run a 195* t-stat. Make sure the fan clutch is working properly, a stuck clutch can make a big dent in MPG's and make sure you don't have any vacuum leaks. Install a vacuum gauge and adjust your driving to maintain the highest possible vacuum readings ( I've found this doesn't apply with EFI ). Once you've done all that just drive it but don't expect great mileage out of it. ESPECIALLY around town. At that point it's very doubtful you'll find any magic bullets that will make any noticeable mileage improvements without spending far more than the truck is worth.

I just went through all that with an '86 Dodge 2WD with a 318, A-727 and 2.94 gears. I went from 7 MPG to 13.8 but spent far more than the truck was worth getting that last 3 MPG. I did pick up another 4.5 MPG after that though.......... I sold the Dodge and bought an '88 Chevy C1500 with a 350 TBI, 700R4 and 2.73 gears. ;) :D
 
#16 ·
Gas mileage

No such thing as good gas mileage with a full size 4x4 truck that usually weights 6 to 7000 lbs stock. Gears in the 256 range may lug it to much sound like mileage is no funage no power, keep the oil indistry alive like all good hotrodders do. :confused:
 
#18 · (Edited)
"1,000 lb. 1/2 ton 4x4?"
I meant minus (-)1000 pounds not 1000 pounds total. I used poly racing seats, will make my own lightweight bed, make plastic inner fenders, maybe gut the doors, etc. I already made an automatic shifter that weighs almost nothing, etc.

"I grew up in PA and ONT and rarely needed 4x4. A good set of snow tires is all you need." That's funny. Come to Iowa in about 2 months. :D It is a commercial vehicle. I only paid $500 and the engine is smoke free with a new eddy carb and tires. Had to fix the rearend ($125).

Some great feedback and some spanking. Anyway I appreciate anyone that took the time to respond. I was a long time bracket racer and thank you all for the feedback.

I wonder if my 90 efi has enough back pressure.
 
#19 ·
"enough backpressure" there's another one of those great automotive myths.. any backpressure is too much. this is why we build free-flowing exhaust systems, to reduce/eliminate backpressure.


if money isn't a big deal, consider a TPI swap, or some other aftermarket multiport efi system. be ready to spend near $3,000 for it tho.

but again, this is like buying a new car.. with what the new vehicle is going to cost you, you can buy a LOT of gas.

when you consider your new vehicle payment..say around $500 a month. plus having to have full coverage auto insurance on a financed vehicle.. this could be anything from $200 to $1000 a month depending on the state on your driving record and insurance co... you can burn a lot of gas for upwards of $1000 a month!!!
 
#20 ·
80's truck, V8 and good gas millage is a funny combination. I wouldn't even worry about it. Sure you can improve it a bit. But as said before from what 15 to 17 mpg? Saving a couple hundred bucks a year? Im sure you can save more on other ends of your business way quicker. As said here before if you want real good millage get a lil 4 banger import and your good to go. Otherwise just enjoy your truck the way it is. I love my 88 dodge W150, its doing everything Im asking for BUT saving gas! :D
 
#23 ·
i was reading this thread and was reminded by what my grandpa said about his truck one day (84 four door, long bed chevy with a 502 and a 3 speed)

we were pulling my dirt stock car to a race one afternoon and i commented on how easily it pulled the car up big hills, he responded "yeah, you should drive it without a trailer, it will pass anything but a fillin' station!"

I know most of you have prolly heard that before, but its the reality of old trucks/cars, they just dont get good mileage very often!
 
#25 ·
Update: SO... not very good milage so far. I got the weight down to 4200 from 5000 Lbs. 600 edelbrock milage carb, performer intake, electric fans, ramhorns with dual 2.5 exhaust. 5x14 air cleaner. Turbo mufflers. Same drivetrain. I think 3.73 gears would help because the vacuum drops pretty fast while driving most of the time like it's lugging. BUT it is what it is and it's a blast to drive. I really like it. I may try a different carb and maybe 3.73 gears later on. For now it's a daily driver. I use it mostly for an (auto upholstery) shop truck. :D It's been super reliable. The 700r4 went out on my 90.... High gear clutch pack :mad:
 
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