i got a 92 f150 xlt with a 302 v8 and i hate my gas mileage i know its not going to be good with a v8 but i was wondering whats everyones best gas saver?? fuel magnet, stp fuel trement etc. thanks

 

Don't start your truck

 

Yes keeping her in the driveway will save gas but seriously, give her a good tuneup. Maybe install a K&N filter. Change the oil regularly. Maybe get slightly larger tires. Some people claim that higher octane will boost mileage but you pay for it at the pump and I have not proven it myself yet to advise.

 

I once though along the same lines as Mike, but then I did it, and it doesn't prove cost-effective. It doesn't even help the milage at all. One thing I did that really did help the fuel milage is an MSD ignition system. I went all the way, I have the 6A box, pro-billet distributor, and coil, but any single one these components will do their part to helping you conserve fuel. Although I did my upgrades in stages that would keep me from giving you an exact or truthful number, I gained 1.5 MPG from the 6A box, and I'd estimate that with the distributor and coil, you should gain 2.0 MPG with no other upgrades. TK

'77 F100, 302 (the aftermarket Prodigy), C4
Cadet Second Lieutenant John F. Daly III
South Carolina Corps of Cadets, The Citadel
The TorqueKing

 

depending on your carb you can have it leaned out some. I had a Holley with a blown power valve and was getting around 8mpg, had it overhauled and started getting 10 immediately. I agree with the MSD ignition, I only have the MSD 5 ($89.00) on my 86 F350, and noticed a difference too.

It also depends on what you are doing with your truck. If it is a daily driver, you should have gotten a toyota. If you haul (like I do) you shouldn't be worrying about it anyway. I get 6 to 7 mpg with my dually. I could spend a ton of money to get it up to 7.5 mpg, but is it really worth it? I could buy lots of fuel for what the upgrades will cost, so I focus on performance and go from there.

 

Clarification: your total improvement should be 2.0 MPG with the complete MSD system installed, that looks a little misleading how I typed it. TK

 

With a 92 you might have a smog test done to see how well the cats are doing. I replaced the cat on one car and the mileage went up 25%. The cat was at least 10 years old and clogged up. It cost me $100 for the cat.

Also the O2 sensors can get clogged up with carbon and injectors can leak, a smog test should tell you what your a/f ratio is and that should tell you if something is bad.

 

What kind of milage are you getting.


Brian

 

Don't even think about magnets and screens etc. to increase power or mileage. They are JUNK!

Fuel additives can help solve a specific problem with a gummed up injector or sticky float valve. My experience has been that they do the most good if left on the store shelf.

Using a higher octane fuel can actually LOWER your mileage. Your engine is designed to use a specific octane fuel. Modifications can change this requirement because the "design" has changed.

 

how areoydynamic is your truck? how about a recent tune up? larger tires decrease gas efficantcy, getting the idea now bud?

gas magnets are worthless.

 

Bigger tires don't necessarily cut your milage, taller tires actually increase it. They decrease your final drive ratio, cutting your cruising RPM. This is assuming that you don't have monster truck tries with a 1' wide tread, which is what Joe's probably talking about. Tall tires are good, but those offroad tires will destroy your economy.

 

You need some of those "85" series tires, tall and skinny. I don't know what your truck has for rim size either. A new set of tires and wheels can't be justified by a fuel mileage increase, there just isn't enough of a difference to pay for them over time. To get an idea of fuel costs we can use some rough figures. Plug in your own annual mileage and gas price for a better comparison.

Annual Fuel Cost:

15,000 miles / 15mpg =1000 gallons X $1.50/gal = $1,500.00

15,000 miles / 16mpg =938 gallons X $1.50/gal = $1,406.00

A savings of only $94 per year, and that is if you even get a 1mpg increase which is doubtful.

 

I have a 96 with a 302 and when I went from the stock airbox+K&N filter to a K&N FIPK I noticed a big difference to my fuel milage and power. Acceleration was smoother and a lot better. Miliage went from 15.5-16 to 17.5-18.5 average(depending on how fast I drive of course). I do a lot of hiway driving. So if you plug in the numbers from the previous equation for me:

15000 miles / 16mpgx1.50gal = 1,406.00
15000 miles / 18mpgx1.50gal = 1,250.00

that is 156 and the cost of the kit was 152. So I paid for the kit in the first year in savings and next year (assuming all stays the same which it rarely ever does) I will save 150 bucks on gas. Also my trucks has 31x10.50's on it, so if you have a taller tire and not so wide you could do better. Another thing that helped was a cap, rotor and plugs (tune up). Also if you are willing to spend the money on it and also are wanting more power you can get a cat-back system. I have a flowmaster system my self with a 50 series 2 chamber muffler and it sounds awesome and probably added to the fuel milage I gained when I put in the FIPK.

 

[updated:LAST EDITED ON 06-Aug-02 AT 11:01 PM (EST)]I've been tinkering with my 78 for quite some time trying to get the best of both worlds. I've been looking for performance and mileage since I drive about 60 miles round trip six days a week.

I have added the MSD that everyone is talking about. I used the 6A and the MSD Duraspark replacement coil. I agree with everyone. It was a really good investment. The idle is smoother, and throttle response is better and it pulls up the hills without a single ping. The technology is about twenty years newer than the original Duraspark box so it has to be an improvement.

I also added a set of headers and a couple of Hooker Aerochamber mufflers. It really helped get the exhaust flowing and it sounds good too.

I installed a Crane advance curve kit to my Duraspark distributor. It gave me a bit of low end torque and it came with an adjustable vacuum advance to help get the ping out of the 87 octane fuel that I've been burning.

I bought a 500 CFM Holley 2300 carburetor. In it's original configuration with 73 Jets and a 5.0 power valve I was only getting about 10 MPG. I have since changed to 68 Jets and a 6.0 power valve. I now get about 13-14 MPG if I drive conservatively and keep my foot out of it. I am thinking that if I change to a two stage power valve, I may be able to drop the jet size a bit more and squeeze another MPG out of it.

My mileage drops off a bit in town because of the 2.75 gears in the rear, but I have obtained a set of 3.00 gears that I'm going to try. My theory is they shouldn't increase the RPM too much on the highway but it should stop some of the lugging that the tall gears cause in the city. If anyone thinks this is a bad idea, let me know before I try it.

I used to work pretty hard making my truck run fast, but lately I've had just as much fun trying to make it as efficient as I can. Who knows, the next step may be a late model fuel injected engine and an AOD transmission.

In any case don't get discouraged. You will eventually find a combination that you will be satisfied with. Every week I try something new. It's become a really fun challenge for me.

 

wl_keller, great post, and I have something to offer on your gear ratio ponderings. The 3.0 will only make a slight difference in highway performance. The C4 transmission that you have will not lockup, mine runs 2500 RPM @ 70 MPH, which I should only be running 2230 RPM due to the 1:1 third gear ratio in the C4. This equates to 10.7% slippage, which is right on specs for a C4. An AOD will lockup on the highway, thus saving RPMs, and so will the (2/3):1 OD gear. 2.75's are slow, and 3.0's will be too. I'm going with 3.89's, which sounds horrible, but with a 2/3:1 OD gear, a 3.89 ratio becomes a 2.59:1 final drive ratio. Even with the steep 3.89's, with an AOD I'll only be spinning 2100 RPM on the highway @ 70 MPH. I'd post the MathCAD worksheet I calculated all this on, but it won't work unless you have the program on your computer. Oh well. Good Luck, and if you know anybody with an extra AOD laying around, lemme know! TK

'77 F100, 302 (the aftermarket Prodigy), C4
Cadet Second Lieutenant John F. Daly III
South Carolina Corps of Cadets, The Citadel
The TorqueKing