Need to improve mileage!

[JustinR]

I have been driving my 71 chevy k10 everyday now and am tired of filling up more than once a week! I am trying to look at all my options.. buy a new car, new gas truck, diesel truck, or try and get better mileage out of my k10. The problem is I need a truck for work, and my k10 works perfect. With the cost of a new truck, more expensive plates, and having another vehicle to maintain, I'm thinking that isn't my best option. My truck has a crate 350 with 15,000 miles on it, th350 transmission, and 3.07 gears with 32" tall tires. I am pretty sure I could pick up some mileage going to 3:73s, just because of the bigger tires. I am also looking at fuel injecting it. I was thinking my options were to go with an edelbrock fuel injection kit. Or find a gm throttle body injection setup. I would even look into swapping in a newer 5.3L if it were worth while. Another reason for wanting fuel injection is because of the really cold winters here, so it would be nice to have.

Please give me your opinions, thoughts, ideas, or whatever else!!

Thanks!

[Sacramento70]

lose the tires and convert to a 700r4 as well as adding fuel injection and i guarantee youll see better mileage

[67ChevyRedneck]

What are you getting now?

There is no magic trick to getting great mileage... I have a 2wd with a 350/700R/3.73 and still get 12 around town and 16-17 highway. For the majority of my tanks I average around 12.

You have a heavy 4x4. It kind of is what it is. You can throw thousands at it, and you may gain a couple/few mpg.

I drive a 99 S-10 2wd reg. cab 4 banger/5spd for fuel mileage, and even that "only" gets 22/23 city and 28/29-ish highway, but I mostly average around 23. I got 31 mpg on one trip I took, but it was backwoods highways where I went 55-60mph the whole way for about 300 miles. If you do that on I85 or I385 around here you'll get killed, so my avg. highway speed is 70-75mph.

My Z71 with modern fuel injection/overdrive, etc (but is really heavy) gets 13/14 city and 17/18 highway.

[special-K]

...S--L--O--W--------D--O--W--N.......Seriously! It`s the most effective way to save fuel "and" money.

My 3/4t 4wd gets 12.5 mpg,what do you get?What type of driving do you mostly do?You can spend money on this or that or keep the money or gas.The best mileage gainer is a light right foot.I get best mileage at 60 mpg with 3.54s/12.50x33s/TH350/350.

[cdowns]

buy a prius if you want mileage

[67chevemall]

1982 toyota 22r pu 4cly 4 speed. $25 goes all month

[68gmsee]

A lot of young people buy these old trucks because they are nice looking and the cool factor, or "tight" as my nephew used to say.

The love affair quickly goes sour when the gas cost is realized. I've been preaching and continue to tell people that the trucks of this era were mainly work truck not cruising trucks. They were used for hauling, pulling, and just occasional trip to the feed store.

In the 70's the desire for creature comforts increased and now we have more cruising friendly trucks. But, if you want one of the old original ones, you're going to get lousy gas mileage compared to what we're used to these days.

Twelve to fifteen mpg highway was considered good back in my old days.

[UltraBlue71]

Originally Posted by 67chevemall

1982 toyota 22r pu 4cly 4 speed. $25 goes all month

Here Here! Hard to beat a 22R on longevity/mileage

Cant have your cake and eat it, usually, look at what you are spending and how long it will take to pay for itself in fuel savings....

[lsx72]

OD transission, and a tuneport injection set up, you can find em on craigslist with wiring all the time for around $300 bucks. or get a painless harness(alot easier and neater) for around $350 more.

[Critter]

If you plan to throw a couple grand at that truck to gain 2-4 mpg, then you will have to drive it for decades before the fuel savings pays for the efi/overdrive/different axle, etc. Now if you are wanting to make a change just primarily for the cool factor and cold starts, and gain a couple MPGs in the process then get after it. Any of the above suggestions are good, just depends on how much $$$ you want to spend. If you change to an OD transmission then you will also have to change your front and rear gears anyway, 3.07 would be too high geared in my opinion. Check this out, it has answered alot of my questions lately.

http://www.grimmjeeper.com/gears.html

[smn69]

There is nothing like driving one of these trucks, but for the money that you would have to put into it to even get close to 20mpg, may not be worth it. I just went out and bought a 93 honda accord with 200000 miles on it to drive to work and back. I got it for $900 and it still runs great. I fixed a couple oil leaks and did a little maintance and it passes emissions without a problem and it gets 34 mpg. I can drive for a week and a half on what it would cost me for 2 days in my truck.

[big_al_71]

Originally Posted by cdowns

buy a prius if you want mileage

+1 on that one I have several here in the dealer for sale!!!!

Originally Posted by 67chevemall

1982 toyota 22r pu 4cly 4 speed. $25 goes all month

I agree 100% dollar for dollar the best investment you can do for gas economy...





I would not spend one dollar in trying to make one of these trucks more gas efficient I would buy me a beater 4 cyl truck (of course if you can get away with one) I dont know if you need a full size truck for hauling or carrying heavy loads.

[cedorris]

If you've got the money you could do a Compressed Natural Gas conversion.

I'm considering purchasing a K5 specifically to convert to CNG.

[Senator350]

1. FI from a junkyard smallblock
2. Newer GM trucks don't get much better MPG.
3. buy an elcamino

[oldgold70c10]

What you might be spending on gas in your old truck is still probably a lot less than the increased cost of insurance, interest on a new vehicle loan, and the other expenses associated with a new vehicle.

[JustinR]

Thanks for the replies everyone! Right now i am getting 17mpg on the highway, and thats canadian size gallons. I know that isn't too bad, but I still would like more. I thought about buying a cheap beater car, but I need a full size truck, or full size suv for work. I am a carpenter and am always hauling lumber. So the long box is really nice.

Senator 350, I really like the Elcamino idea, except there is no way I could get away without 4x4 in the winter.. we get tons of snow up here!

OldGold70c10, you are very right! I priced out some new vehicles, and the insurance difference per year is almost $1000.00. Not to mention payments, and other costs.

The cold starts are a lot of the reason I want fuel injection, it's gets to -40 here in winter, and the carb becomes a real pain.

Thanks for all the ideas!

[JustinR]

Originally Posted by special-K

My 3/4t 4wd gets 12.5 mpg,what do you get?What type of driving do you mostly do?You can spend money on this or that or keep the money or gas.The best mileage gainer is a light right foot.I get best mileage at 60 mpg with 3.54s/12.50x33s/TH350/350.

I would say about 50% highway and 50% city driving. I just filled it up today, and I will see what my combined mileage turns out to be.

[brad_man_72]

Originally Posted by JustinR

Thanks for the replies everyone! Right now i am getting 17mpg on the highway,

Thanks for all the ideas!

im not getting much if any better mielage with my 67 5.3 4l60e 3.73 2wd, but it does start right up every time, and has a cool factor.

my 96 4.3 4x4 sonoma got 16mpg
my 4 cylinder 88 mitsubishi mighty max got under 20mpg

[brothers69c-10]

I envy anyone that gets better than 10 miles to the gallon in an old chevy 4x4. I'm getting rid of the smallblock and swithching to a big block, just for the simplereason the big block won"t work as hard.

[Critter]

Originally Posted by JustinR

Thanks for the replies everyone! Right now i am getting 17mpg on the highway, and thats canadian size gallons.

I don't know much about Canadian MPG, but I beleive that 17 Imperial MPG = 14.15 US MPG. If that is the case, I doubt there are many people (if any) getting better mileage than that with a 67-72 lwb 4x4...INCLUDING the EFI conversions. It's just hard to push a brick at highway speeds.

[Lippyp]

Whats the price/availability of LPG like over there? A gas conversion could be the way to go. In the UK LPG (Liquified Petroleum Gas) is about half the cost of petrol(gas!) so a conversion effectively instantly doubles your MPG.

[mrein3]

When I got my truck it had a tired 350 and a 3-speed manual (three on the tree). It got 13mpg on the highway on good days. I got 10 pulling my boat.

I didn't mind the three on the tree but it was a real hassel at the boat ramp. I decided to switch to an automatic.

I spent LOTS of time and energy in an excel spreadsheet with my real world data in an attempt to figure out if it was worth it to put in a 700r4 or simply get a th350. Back when I did this gas was $1.259/gallon. I calculated that even if gas got to $1.799/gallon it would take 10 years to pay the difference in the cost of rebuilding a th350 verses a 700r4. (Keep in mind my truck is a 4x4 so a 700r4 costs more because you need to put in an aftermarket output shaft to work with the NP205 transfer case).

Well as everybody knows, gas went right past $1.799 and went over $4 for a while. But in my case the pay back was still a long way out because about the only time I'd be using OD I'd have my boat attached and since you can't tow in OD and 3rd in the 700r4 is the same as 3rd in a th350, I wouldn't be 'saving' anything. I went with the th350.

I guess what I'm trying to say is that YOU need to figure out YOUR needs for the truck. IF you need it for work and you do drive it a ton of miles per year, it may make a ton of sense to run an OD tranny.

Another factor to consider is that my truck, with 3.73 gears really is screaming at 70 mph on the interstate. However I rarely go that fast so that isn't a problem.

More things to consider. Your 3.08 gears are already 20% better for highway mileage than my 3.73s. IN THEORY, you should be getting 20% better highway fuel mileage than my truck. The OD in a 700r4 is .7:1 so again IN THEORY you'll get 30% better mileage just by making that switch. However I've read here in this forum a million times how folks with 3.08 gears switched to a 700r4 and got WORSE mileage. BUT you got 32" tall tires. Standard tires are 28". 10% of 28 is 2.8. Two times 2.8 is 5.6. 28+5.6 is 33.6 so you're 32" tires are nearly 20% taller than stock so in essence you're running 3.73 gears.

Still another thing to consider. How do you know you're getting the mileage you thing you're getting? Is your speedo correct? If it isn't you have no way of determining your actual mileage now so your data is crap. If your data is crap, how will you know if you make it better or not?

[Critter]

Originally Posted by mrein3

More things to consider. Your 3.08 gears are already 20% better for highway mileage than my 3.73s. IN THEORY, you should be getting 20% better highway fuel mileage than my truck. The OD in a 700r4 is .7:1 so again IN THEORY you'll get 30% better mileage just by making that switch. However I've read here in this forum a million times how folks with 3.08 gears switched to a 700r4 and got WORSE mileage. BUT you got 32" tall tires. Standard tires are 28". 10% of 28 is 2.8. Two times 2.8 is 5.6. 28+5.6 is 33.6 so you're 32" tires are nearly 20% taller than stock so in essence you're running 3.73 gears.

Still another thing to consider. How do you know you're getting the mileage you thing you're getting? Is your speedo correct? If it isn't you have no way of determining your actual mileage now so your data is crap. If your data is crap, how will you know if you make it better or not?

I think you went the wrong way with the math as far as the tires go. A taller tire will effectivly make a higher final ratio. So if you have 3.08s with 28in tires and then you change to 32 inch tires, you will be turning less rpms at a give speed than you were before at that speed. If you go with your "20% taller than stock" statement that would effectively make a 3.08 axle feel like a 2.50 give or take. My concern from talking with other people in this posistion is that a 700r4 with 3.08s AND 32 inch tires that your overall drive ratio will be too high geared and you will have trouble even getting the tranny to shift into overdrive.

I do agree about the speedo and quality of the MPG data...

[mrein3]

Originally Posted by Critter

I think you went the wrong way with the math as far as the tires go. A taller tire will effectivly make a higher final ratio. So if you have 3.08s with 28in tires and then you change to 32 inch tires, you will be turning less rpms at a give speed than you were before at that speed. If you go with your "20% taller than stock" statement that would effectively make a 3.08 axle feel like a 2.50 give or take. My concern from talking with other people in this posistion is that a 700r4 with 3.08s AND 32 inch tires that your overall drive ratio will be too high geared and you will have trouble even getting the tranny to shift into overdrive.

I do agree about the speedo and quality of the MPG data...

I stand corrected. You are right. You need to go 20% the other way. You have what is the same as a 2.464 rear (and front) end gears.

Most ratios are approximately 10% different from the next. 3.73s are 10% different than 4.11s. 3.08s are 20% different than 3.73s. I think there is a 3.54 in between on 2wds which is about 10% different than the 3.08s and 3.73s.

If 3.08s and 700r4s don't play nice together, I'm certain that your truck will get worse mileage with an OD tranny as your engine will be lugging if it makes it to OD.

[gmc1971harwich]

hey how about all u 6 cyl owners. what are you getting for gas mileage? that might be a way to go, combined with a 700r4 trans i would think that combo would give you the best mileage possible for your truck, wont go as fast but should be pretty economical.