Dont take this as ignorance but as gaining knowledge

[LeatherMan69]

OK. I've touched on this subject a bit in another thread, but it wasnt the focal point of it. So here we go....

Now I want to know all the tricks of the trade to squeezing all the MPG's i can out of this beast of a truck. I did the math and currently getting 8.8mpg. Like i said IM NOT IGNORANT I KNOW THESE TRUCKS ARE GUZZLERS! So just know that. But im a firm believer that just cause its not a drastic change doesnt mean it shouldnt be done. So the obvious one is Air intake, a K&N isnt a bad idea ever. Tires being inflated at the correct PSI, and keeping the foot off the floor. BUT driving style aside. Lets talk some inexpensive and easy ways to get some more MPG's out of these things!

[RandyP]

Always drive with the wind and down hill. Speed up going down hill, slow down going up hills (don't let the cruise do it, you'll do better minding your own gas pedal).

[chevymotocross]

Don't start the engine. Pay someone less than the price of fuel to push or pull the truck to destination.

[glhman222]

what is your truck?
2wd?
what engine?
what trans?
what Rear Gear Ratio?
Year?

advice number 1 drive with tailgate up if you havent been

im part of the ecomodders website so ive learned a few things

i have a list on planned mods to my own truck but its not finished this is what i have so far tho
Mods
1. Alternator Modification
a. Less Engine Load
i. Alternator Only Charges when brake circuit is engaged
2. Flat Wheel Covers
a. Reduce aerodynamic loss of wheels
3. Aluminum Front Bumper
a. Reduced Weight and Aerodynamic advantage
4. Tucked Rear Aluminum Bumper
a. Reduced Weight and Aerodynamic advantage
5. Windshield Wiper Removal
a. Aerodynamic Advantage
6. Light Weight Seats
a. Weight Reduction
7. Taller Tires
a. Better Gear Ratio
8. Belly Pan
a. Increased Aerodynamics
9. Block Heater
a. Decrease Warm up time
10. Synthetic Motor Oil, Transmission Oil, Wheel Bearing Grease, Gear Oil
a. Decreased Friction
11. Power Steering Delete
a. Less Engine Load
12. Electric Cooling Fans
a. Less Engine Load
i. Thermostatically Activated

13. Remove Passenger Mirror
a. Increased Aerodynamics
14. Smaller Drivers Side Mirror
a. Increased Aerodynamics
15. Remove Handles
a. Increased Aerodynamics
16. Exhaust Headers
a. Decreased Engine Back Pressure
17. Gasket Match Inner Engine Mating Surfaces
a. Deceased Effort to breathe in or expel gasses
18. WideBand A/F Gauge
a. For Tuning Carburetor for increased fuel economy
19. Led Lighting
a. Decreased Alternator Load
20. Aerodynamic Bed Cover
a. Increased Aerodynamics

[cableguy0]

Switch all fluids to synthetic. Use synthetic grease at the wheel bearings. Properly tune the engine. Theres no reason you cant get at least 12 mpg. The truck in my sig was getting 11mpg on the highway until i went with a 4500 stall converter. Now it gets like 11 gallons to a mile. Drive smoothly. If you take off gradually it makes a huge difference. Bring all ignition parts up to par. New cap,rotor,wires,plugs,coil etc. Your not going to do one thing and gain 5mpg but all the little things will add up.

[misternash2]

for what it's worth i checked my mileage sunday. all interstate running 75mph. i got 16.5mpg. i'm just throwing around numbers to share knowledge like the title says.

5.3/4l60e
3.08 rear ratio
275/60R15 tires.

i know the width of my tires aren't giving the best mpg's.
and i know 3.08's don't keep the engine in the premium rpm range.
oh yeah, and i know my truck's shaped like a brick...haha

[red rumbler]

lose all spare weight possible. if you have junk hopping around in the back lose it! every pound counts. change all fluids ( i mean all ) to synthetic. and what type of driving do you do most? if your not racing it around get lower gears 2.70 ect and youll get better fuel milage lower the number means higher top end and less rpm to hit cruzing speed as for arrow dynamics tunneau cover? and if your running alot of electronics cut em off when you dont need it. also get it tuned and if you have the money get electric fans and electric water pump. if you go electric it takes more stress off your motor because the serpentine turns all that and robs hp and mpg

[misternash2]

food for thought: how long will it take to save (in fuel) the amount of money it costs for modification? losing junk? free. using as little power as possible? free. electric water pump? i don't know how much improvement it will give in mpg's. but i'm guessing it's gonna take a lot of miles to pay you back for the cost of an electric water pump. (especially for a gen3)

consider this. if you went from 8.8mpg to the 12mpg that cableguy's suggesting, (which i know is possible)
10,000miles a year / 8.8mpg = 1136 gallons. X 2.75 a gallon = $3125 per year
10,000miles a year / 12 mpg= 833 gallons. X 2.75 a gallon = $2291 per year
so that's $834 you'll save every 10000 miles.

how long do you plan to keep your truck? how many miles per year do you drive? and how much will it cost you to get to 12mpg? these are all questions you'll have to answer to weigh out how long it will take to save the money you spend for increased mileage. for what it's worth, i did the math and my 5.3 swap will take about 18,000 miles to pay for itself in fuel alone. (it cost $3000 total and i went from roughly 8mpg to 16mpg) and i'll admit that i could have had the carb tuned and got better than 8mpg. by the way, i wanted to do the 5.3 swap to make my truck cooler too. it wasn't strictly a mileage thing. just toy around with the numbers and you'll get an idea of how much everything's worth.

[GMC Guy]

nobody's mentioned an overdrive trans?
i get about 10 in town and 12 highway with the combo in my sig. But i can't wait to get my 700r4 and 3.73's installed. should be getting around 17-20....with a light foot......we'll see if that happens

[rakerkman]

I stuck about a grand into my truck and went from 8.2 mpg to 9.1 mpg. Then I put a truck cap on that I got for free and went from 9.1 mpg to 11.5 mpg. By the way its a 70 C-20 350/350/4.11

[LeatherMan69]

Well this is my daily driver. Kinda just got it so i dont know the specifics of it yet, Just been driving it. Its a 350/350trans. Im not sure on the gearing. I do baby the foot pedal now matter how much it ticks off the people behind me. Like some of you pointed out there are some simple and free solutions... and i will do all that. Starting with the giant farm bumper on the rear of the truck for wieght.

My concern with synthetic mainly oil is my truck likes to spit a little out and burn it a bit. Might get expensive if thats the kind of qt of oil i gotta haul in wheel well

I think i will first work on the wieght. the air flow, possibley the exhaust and wind resistance and see what i'll come up with then. Plus maybe a tune up and carb cleaning is in order.

[LeatherMan69]

FURTHER MORE... Where do you find the gearing ratio?

[LeatherMan69]

Originally Posted by misternash2

food for thought: how long will it take to save (in fuel) the amount of money it costs for modification? losing junk? free. using as little power as possible? free. electric water pump? i don't know how much improvement it will give in mpg's. but i'm guessing it's gonna take a lot of miles to pay you back for the cost of an electric water pump. (especially for a gen3)

consider this. if you went from 8.8mpg to the 12mpg that cableguy's suggesting, (which i know is possible)
10,000miles a year / 8.8mpg = 1136 gallons. X 2.75 a gallon = $3125 per year
10,000miles a year / 12 mpg= 833 gallons. X 2.75 a gallon = $2291 per year
so that's $834 you'll save every 10000 miles.

how long do you plan to keep your truck? how many miles per year do you drive? and how much will it cost you to get to 12mpg? these are all questions you'll have to answer to weigh out how long it will take to save the money you spend for increased mileage. for what it's worth, i did the math and my 5.3 swap will take about 18,000 miles to pay for itself in fuel alone. (it cost $3000 total and i went from roughly 8mpg to 16mpg) and i'll admit that i could have had the carb tuned and got better than 8mpg. by the way, i wanted to do the 5.3 swap to make my truck cooler too. it wasn't strictly a mileage thing. just toy around with the numbers and you'll get an idea of how much everything's worth.

I plan on driving this thing for a long time. But when my 69 is done i will split the difference for sure, But that'll be a couple of years. I drive at least 20-40mi a day. So MPG is a concern. Mainly for the ol' pocket book.

[D13]

Not knowing what you're driving makes it very hard to help.
My 72 Longhorn got 9.5mph, 9.0 with 10,000 on a trailer behind it.
My 90 454SS got 9mpg.
My 81 with 4.1l (250) L6, 3 on the tree, 3.42 and 265/78 16.5 radials got 15.
my 88 xcab 3/4 ton with 5.3/ 4l60E /3.42's gets 15
my 87 6.2 /700R4 /3.08 / P235/75R15 gets 23mpg + (diesel)

So, here's the summary
#1 thing is how you drive it
Cruise control whenever possible.
Dump the clutch or cruise early and let the truck roll to a stop sign. Your target should be to never apply the brake above 35mph. Braking wastes rolling energy (as a not the partial hybrids shut off the engine as you're rolling to a stop).
NEVER go over 65mph (i lose 2mpg 65 to 72).
NEVER go under 45mph if you can help it (air resistance and rolling resistance cross at his point), you won't be in the engine's happy speed.
Accelerate like there's an egg under the throttle.

My dad never got more that 15mpg with his truck, I could get 17mpg by driving 48 vs 55 and pushing in the clutch way before stop signs.


Set your drive train up for MPG:
Select your gearing and tires to get 1600RPM @55mph (bottom of max torque range at cruising speed), or 2000RPM at 70mph.
Less cubes = more MPG to a point.
Lean out your carb, use a quadrajet or edelbrock with small primaries. A q-jet with the back barrels disconnected has no power but will give great MPG. Matter of fact GM did this on the 77 B car with the small V-8...
TBI wil get you .5mpg in summer but allows you to drive off cold in winter (+1mpg)
Despite what anyone says, a cab high topper has been worth 1-2mph on every truck I've put one on, if it was driven at highway speeds.
Keep your tires properly inflated and a good alignment.

On my diesel I've taken out the EGR, the next step is electric fans (good for 15HP and 1mpg), free flowing air intake, and free flowing exhaust. Aiming for 25MPG in a 4500# truck.

[BigBlocksRule]

Originally Posted by RandyP

Always drive with the wind and down hill.

Run taller tires on the rear than the front, you'll be going down hill all the time.

Aim your truck west and hang it in neutral. The rotation of the earth will turn under the truck and you'll be rolling for free.

Honestly, the two things that hurt trucks are weight and wind drag. The only way you're going to significantly improve mileage in ANYTHING that has a correctly tuned engine in it is to lose weight and reduce wind drag. You'll probably end up spending more money to increase mileage than you'll save over the life of the truck. Tune it and drive it.

If you want great gas mileage, buy a compact car for driving daily and use the truck when you need it.

[RuralRoute C-30]

Originally Posted by BigBlocksRule

Tune it and drive it.

If you want great gas mileage, buy a compact car for driving daily and use the truck when you need it.

Works for me.

Mark

[tucsonjwt]

I concur with those who say to drive an economy car if you want gas mileage, unless you actually need the truck for daily heavy hauling - in that case buy a small truck. New trucks, or old trucks with new truck drive trains installed, can get about 15-16 city/ 18-20 highway, so if gas mileage is paramount and you drive as much as you state, then it could payoff in the long run. I know this is not allowed here, but Ford has a new V6 with lots of horses that is up around 20+ mpg, so maybe GM will come up with a competitive engine in the future. Check out pickuptrucks.com for a good review of the new trucks, both light and heavy duty.

[misternash2]

Ford has a new V6

i was under the impression that this forum isn't too keen on the f-bomb. maybe a moderator can step in here and keep it bowtie friendly? haha!!

i really didn't realize how much a camper shell helps out. i think there's an understatement on "properly tuned" in cableguy's post. i'm not very good at tuning carbs, so if it was me i'd take it to someone who know exactly what they're doing. in the carb department, a little money spent on someone with lots of experience and knowledge could come back fairly quickly. in my opinion.

[pig rig]

Let me help you out with some simple mods that can help increas milage
on my crew cab with a 454 I went from about 8.5 to 15/16mpg first I started with getting it tuned up (its a tbi engine so this incloded replacing sensors) then I added a MSD 6AL ignition box and I opened the gap on my plugs to .45 I never got a chance to check my milage after I did all that because I puked the motor.
so it was rebuild time I did a few things to help with horsepower gas milage wasnt a consern as good ol' horsepower was. so It got a bigger cam dome pistons bigger valves and a few other things I also added a airraid spacer and and built a cold air intake. then I had to put headers and 3"exahust on it.

well after getting it broke in and making some tweaks I drove it from here in northern washington to so. cal I put just over 4000 miles on it on that trip and I calculated milage every fill up and I was average 14mpg well on the way home the clutch fan went titsup so I pulled the fan and ran it home with out a fan and thats when I figured out I was getting about 15/16 depending on how many passes I had to pull per tank so I got home and instaled an electric fan. Ive sents started playing with the tbi and Ive dropped down to about 14mpg. but Ive got a couple of other changes that will requier big money I want to make so I can hit my goal of 18mpg out of this fat pig

[camshaftgsxr]

you could always buy a honda civic for $200, then drive at 30+ mpgs till it dies and crush it for $300

[Edahall]

Instead of focusing on engine efficiency which not much can be done there, focus on aerodynamics. Aerodynamics is probably one of the biggest reasons why newer trucks get better fuel economy.

Regarding aerodynamic mods, here are some ideas.

I would first start off with extending the front bumper down to almost the ground and installing a cover that angles downward from the cab down to the tail gate. You can use thick rubber to bring that bumper down. There are a bunch of other things you can do such as using pizza pans as hub caps or rear fender skirts but then the truck starts to look silly. Also, make sure you are using low resistant tall and skinny tires. If your truck is 1/2 ton, go with a 30x9.50 and if it's 3/4 ton, go with a 235/85/16.

Here are several truck that were ecomodded to the extreme to give you an idea what I was explaining. Pay particular attention to the slopping canopy and the front bumper. These guys also smooth out the bottom of their trucks with a pan so they don't need to extend the bumper so far down.

--And oh by the way, that 1994 Toyota T-100 went from 23.3 mpg to 32 mpg at 75 mph. And that truck was a lot more aerodynamic than our trucks to begin with so there's even more gain to be had on our square bodied trucks.

[tucsonjwt]

As I sit here, I have my old beater loaded with dirt and rocks I am about to go to the dump. The dump conversion is something I rarely use, but when I do use it the truck gets quite a workout. So, even though I have the truck in top mechanical shape, I still only get 8-11 in the city, and probably 6 mpg with the load of rocks. A 454 3/4 ton beater is perfect for this purpose. I only drive the truck 2-3K miles per year, so any money spent on fuel saving would not pay back in real dollar terms.

If you drive a lot with your pickup box empty then I think you are driving the wrong vehicle, if you want fuel savings.

I used to buy new fuel saving vehicles frequently, but since I don't drive much every day I just rent an economy car when I need to travel a long distance.

You can rent nice little cars for $13/day total cost on the weekends, and about the same for a weekly rental. My last two rentals were a 2010 Honda Civic and a 2012 Hyundai Spectra and the both got over 41 mpg on the highway.

[motornut]

if you've been removing smog stuff, you need to reset, any timming /spark changes
more air by flipping the breather cover
taller tires
gona change from 2/brl to 4/brl
for winter warm ups put in an auto start,start it and it can turn off after 10 min or so
instead of 20/30 min cause the phone rang etc ......works for AC too

[Dalaigh]

Originally Posted by LeatherMan69

My concern with synthetic mainly oil is my truck likes to spit a little out and burn it a bit. Might get expensive if thats the kind of qt of oil i gotta haul in wheel well

My suggestion is get this squared away first. If your engine is spitting out oil then it isn't work efficiently. Find the oil leaks fix the oil leaks, if it's burning oil, look into a rebuild. The engine is like an air pump the more air in and out equally the better it runs, but if the pump isn't lubricated properly then theres added friction and the mods you do down the line aren't going to help any.

Electric fans are a great idea too.

After that I would look into a 700r4, that extra gear will help a lot. Do you tow with this truck? If not then look into taller gears like 3.08's, 2.73's and with the overdrive you can probably get away with 3.42's.

After that if you don't care about performance and you just want fuel economy look into a 2 barrel carb, you won't have that extra punch for passing, but they use less fuel. Or, which would be better, look into an aftermarket fuel injection system. A well tuned carb is good, but not as good a EFI.

Is the truck 2wd? If so look into lowering it, I don't mean slamming it to the ground, but if you lower it say 2/4 or 4/6 just enough to get less air moving under the truck (where theres the most friction) you should get some MPG out of that. Oh, and if your truck doesn't have a lower bumper valance, get one. It's designed to keep as much air out from under the truck as possible.

You don't need a topper, but a soft tonneau will help.

Also if you don't do any towing or carry any heavy loads, look into low friction tires and light weight rims. Make sure all the bearings at your wheels and in your suspension and steering are well greased, this will limit the friction to the wheels. Check your brakes, make sure they are set properly so they are not dragging on the disc's or drums, this will also limit drag on the wheels.

After all thats done, if you're not happy with the mileage you're getting, you can start shedding wait with stuff like fibreglass fenders, hood, bumpers, and even doors if you'd like. You could also remove the PS pump if you'd like, but personally the gain is not worth the extra work to steer at low speeds. And removing your wiper arms just sounds stupid to me, sure they aren't aerodynamic, but I quite like being able to wipe my windows in the rain. Stuff like that are for people trying to hyper mile, and frankly our trucks are not really the best candidates for that.

The best thing you can do to get the best MPG out of your truck is first get it running in tip top shape, otherwise everything else you do is not going to benefit you at all.

[Corts60]

I agree with those who say get an economical car if you drive a lot. Price it out to where you will break even with the money spent for the car vs. fuel savings within the first year or 10k miles.

The only way these square bodies are ever going to get great mileage is if they are diesel and you drive like a grandma. My truck gets 17-18 MPG in the city and 22-23 MPG on the highway depending. I get 14 MPG when I tow a 1500 lb trailer (If you aren't a patient person, don't ever tow with a 5.7 diesel).

Here are my stats:

Non-turbo diesel (sacrifice horsepower here for fuel savings)
Th400 w/ overdrive
3:73 rear end
275/60/15 BFG's
Tonneau cover

My truck has a couple tired injectors and the injection pump is on it's way to needing an overhaul as well. If those components were up to par, I'd be somewhere around 20 MPG in the city and 25-26 MPG on the highway, as I used to get those numbers.