mpg method

[65 mustang]

so I got a stock 302,c4,3:50 gears with 32" tires. the best way to pick up mpg is going to be what in your opinion?? I'm cheep so let me know your ideas?
new gears
4r70
5.0 efi
all the above is the correct answer I'm guessing??

 

[ObscureMachine]

You drive a brick. MPG is not really an option.

 

[thegreatjustino]

Lower gears will reduce the mileage. Overdrive transmission will never use the overdrive gear with your current setup - would require a re-gear to use the overdrive correctly.

EFI might gain you a couple of miles per gallon. Figure how long that will take to pay for the cost of parts.

 

[Broncobowsher]

How much money do you want to loose? Buying fuel will be cheaper then getting better gas mileage.

Overdrive won't do you any good with the 3.50 gears.
The 3.50 gears are pushing the limits of a C4 on 32" tires. You are getting close to the point where you are going to be slipping the convertor at highway speeds/loads.

Depending on the tune of the engine, there may be gains there. I would probably just do one of the self learning EFI kits. Gains here are only based on how bad the carb is now.

 

[spap]

Buy a Prius and save the bronco for weekends

 

[B RON CO]

Hi, what kind of milage are you getting now? My 66 6 cylinder will get 17 MPG on a long cruise. You can try more tire pressure and less lead foot. How do you measure MPG? Fill the tank, drive until you are below 1/4 tank and fill it again. Then divide miles by gallons. 120 miles divided by 10 gallons is 12 miles / gallon. Good luck

 

[Boss Hugg]

Hi, what kind of milage are you getting now? My 66 6 cylinder will get 17 MPG on a long cruise. You can try more tire pressure and less lead foot. How do you measure MPG? Fill the tank, drive until you are below 1/4 tank and fill it again. Then divide miles by gallons. 120 miles divided by 10 gallons is 12 miles / gallon. Good luck

I think he's probably asking because his speedo is off enough that it doesn't measure accurately.

After changing to 5.13 gears, My speedo shows 90 at 75. It's cool that I get away with speeding like that.

To answer the OP, I think you're best bet is using a GPS tracker, maybe on your phone to track the miles you drive. The problem is that if it misses out on 10 miles because you were skimming thru music or something, that distorts your numbers.

 

[JAFO]

Every dollar you spend towards better gas mileage is also money that could be spent on gas. There will be some time before you get to break even. I chuckle when someone goes out and buys a prius to save on gas. They have justified it in their mind, but they just spent say $30K on a car. They could go buy an inexpensive gas hog and probably never spend the $30K in gas. The prius will be worn out and not pay for itself. Friend with a prius had the head light go out. Fix was a $600 light control board. Where is the savings? People want some warm fuzzy feeling when they are at the gas pump. I knew this guy that was actually carrying a five gallon can of gas in the back of his Subaru wagon on long trips so he didn't have to stop at a gas station on interstate that costs more per gallon. I explained to him that say he is saving .15 per gallon carrying a bomb in the back of his car. With a 15 gallon tank that is $2.25. Is it really worth it? It wasn't to him once he thought about it.

Do the math. Say your Bronco gets 10mpg. To drive 100 miles uses 10 gallons of gas. Let's say $2 a gallon to make things easy. It costs $20 to drive the distance.
Now you spend money to get up to 12mpg. Now it takes 8.3 gallons to drive 100 miles. That would be a cost of $16.6. You saved $3.4. Depending on how much you spent on upgrades, it might take a while to break even.

My daily driver is an FJ40. It is a heavy brick pushing air down the road. I have never checked my mpg. It is paid for, I love driving it and could care less the mileage. Anyone with a vehicle that has a car payment, that payment needs to be figured in on how much the vehicle costs to use each month.

Of course just my opinion. I say drive that Bronco, enjoy it like it is.

 

[spap]

The Prius comment was a joke, it takes more resources to build a Prius than it will ever save especially gas. Also, it s going to come to a time of 1000s of large batteries that can't be recycled anymore causing problems in bone yards.
But you could buy a used small car that would be less money than the mods to the bronco and be ahead of the game.

 

[JAFO]

The Prius comment was a joke, it takes more resources to build a Prius than it will ever save especially gas. Also, it s going to come to a time of 1000s of large batteries that can't be recycled anymore causing problems in bone yards.
But you could buy a used small car that would be less money than the mods to the bronco and be ahead of the game.

Agree with that. So true. You are right, but no fun driving a small car .

 

[Slowleak]

There are diminishing returns when trying to improve mileage. Unless it is horrendous, I would just make sure it is tuned properly, tires are at the right pressure etc, and drive conservatively(if you can ).

Some people with good mileage still try to improve it and it takes a long time to payoff. I did some math while having my morning coffee...

Let's assume someone drives 10,000 miles per year, gas costs $2.50/gallon, and they spend 2000 to get a 2mpg improvement:

If they currently get 10mpg, they save 416/year and break even after 4.8 years.

If they currently get 15mpg, they save 196/ year and break even after a whopping 10.2 years.

If they drive half that distance per year then the payback time obviously doubles. I just don't even bother to pay attention to mileage in any of my vehicles. I buy reasonably priced gas and just drive them.....

 

[Rustytruck]

Your engine being a 1977 model has allot of emission equipment. Make sure all of that stuff is working properly. I would replace every vacuum hose you can find. It is very noticeable the difference that can make if no one has been maintaining that stuff. A narrower tire would help and a re-gear of your axle would make the best of what you have. Then I would look to advancing the timing to about 12 degrees advance at idle and re-adjust the carb. A good cleaning of the carb and a new carb kit would probably help too.

When dealing with the carb work to make the choke functions work properly. Coming on like its supposed to and coming off at the right time. Make sure you have the proper thermostat.

Since your odometer and speedometer are out of calibration to the tires you are running use a GPS for miles traveled and gas consumed for your mileage calculations. If you push a stock Bronco up and beyond 60 mph you will take a severe mileage hit. These were built during the gas wars where everyone was promoting 55 mph that is the sweet spot.

Broncos have horrible street mileage so anything you can do to help get the truck up and moving as efficient as possible is where you will see mileage relief. Unfortunately the combination of big wide heavy tires and miss matched gearing to poor engine power ratio has you into an expensive quandary.

Especially when chasing down the path of more modern fuel injection motor, overdrive transmission, and needing proper gearing in the front and rear axles to make it work properly.

 

[blubuckaroo]

I got my best mileage on my '77 when it was in completely stock form. Working emissions equipment, C4 auto, and G78 tires. I got 18 MPG.
The key isn't the engine speed, it's the car's speed. The breaking point is about 50 mph.
Chances are, I'll never drive that slow on a long trip again. %)

The reason for switching to an OD tranny is more about drivability than mileage.
There's only so much you can do with a three speed tranny regardless it's manual or auto.
With tires bigger than stock, you're either going to be facing a lugging start, or teeth grinding highway driving, depending on your rear gear ratio.
Overdrive opens those options simply by adding more gears.

In my case, I do a lot of freeway driving where you'll get run over if you drive under 75. I have the overdrive to handle that, but I do realize I'm way out of the car's ideal mileage speed. %)

 

[sykanr0ng]

The speed vs mileage lesson was one I learned early.
My first vehicle was an IH Scout II in the late '70s.
Stock tire size, no lift, same brick-like aerodynamics as our Broncos.

It would get 13 miles a gallon at 75
It would get 20 miles a gallon at 55

 

[73azbronco]

so I got a stock 302,c4,3:50 gears with 32" tires. the best way to pick up mpg is going to be what in your opinion?? I'm cheep so let me know your ideas?
new gears
4r70
5.0 efi
all the above is the correct answer I'm guessing??

Buy a used Toyota Cellica, immediate 30MPG gain. Seriously, anything over 12-15 is good I think. This is a brick wall riding on Hindenburg sized tires dragging a parachute.

 

[BRONCOchild]

I save tons on gas. I basically gas it up, then park it over the week and only drive it on the weekends...lol. But, in all seriousness, good luck. I get 9mpg, uphill, downhill, sideways, rain, hail, sleet or snow.

Maybe, 10pmg now that I have smaller diameter and less aggressive tread tires.

 

[Rickb1b]

I bumped my MPG by about 2 by installing the FITEC EFI. All total I think it cost me about $1,000. I drive my Bronco about 2,000 mile a year. So I think my payback is around 20 years. But I do like the EFI.

 

[blubuckaroo]

If your biggest concern is great mileage, here's what you could do and still have a nice ride.
>Don't go too wide with your tires.
>Get rid of excess weight from the extra gas tank, and unnecessary heavy steel items like rock skis, heavy bumpers, winch, and overbuilt roll cage.
>Since you'll be limiting your top speed to 55-60 mph, set up your gearing accordingly. Aim for gearing that will match your engine's maximum torque rpm to that top speed.

Wow! sounds like a stock Bronco, doesn't it?

And if you were to make a couple of well thought out mods like electronic ignition and fuel injection, you would probably squeeze out a bit more mileage.

 

[DirtDonk]

I always tried to do things to get better mileage out of my '71 when I was daily driving it. But I never once thought of the payback period. Total cost was never a concern (other than flat out not being able to afford some things) and I simply wanted it to run the best it could, while getting the best mileage possible.
Most of my mods gained performance or drivability, while never lowering mileage. So even though most of them did not gain me a think in the MPG department, I considered it a total win to not lose MPG either!
Small 4bbl carbs, better ignitions, different tires, etc. All did what I expected and made the drive more fun without hurting mileage.

I don't agree that lower gearing is automatically worse, or that taller gearing is better for mileage. Depends on the overall package.
In the case of my fuel injected '68 with 4.56's and just barely 30" tall tires, I bet I can increase the fuel economy with taller gears.
I can squeak 20mpg out of the 5.0 now if I stick to 55 mph and don't spend a single minute driving in the city. If I try the 4.11's I bet that goes up a tick because I can lower the rpm without the engine struggling.
Around town it's exactly the same mileage as my '71 was with stock engine.

Paul

 

[Slowleak]

My 77 is pretty much stock under the hood expect for a Crane spring kit. I never measured my mileage but I noticed right away that I spend a lot less time at the pump.

I now get all the advance in at a much lower rpm, so it's great for driving around town, which is what I do. Its a quick cheap fix, and it made a huge difference for me.
https://www.summitracing.com/parts/crn-99607-1?ibanner=MobileSwitchNo