Full length skid plate - mpg

[Roert42]

I did not have any issue with pinging on 87 prior to the upgrade. I only run 3.5psi boost at the moment so the stock tune is able to compensate for the added air and 93 octane. The only thing I upgraded besides installing the supercharger was a bigger fuel pump.

I bough the Moddbox Kit for $1800 on sale, plus rebuild FORD M80 supercharger for about $800 (the GM ones are a dime a dozen, but this kit is designed to work with a ford one which are not as easy to find). So an extra 70 or so miles for $2600

Another note, @PetroleumJunkie412 had is stock engine tuned to optimize fuel economy on 93, and was getting 18.6mpg combined. Something else to consider.

 

[85_Ranger4x4]

SOHC should run 87 fine out of the box.

I went from old mud tires to new all terrains and mileage did not change, still about 18mpg highway.

 

[Curious Hound]

As far as tires go, I would bet air pressure has a much bigger affect on mpg than tread design. Skinnier tires probably get better mpg, too.

 

[RonD]

4.0l SOHC runs 9.7:1 compression ratio, so will ping on 87 octane, which is why it has a Knock Sensor
9.3:1 is about the upper limit for 87 octane

Yes, you would get better MPG, so more range, using 91 octane if that was the goal, but for the cost, 87 octane would be cheaper even with the lower MPG

 

[Shran]

Seems like the easiest option would be to carry a gas can and a few gallons of fuel with you. Or make your truck as light as possible, with as much air in the tires as possible, and keep your speed set to where it makes the best mileage. I have always been able to get high teens in RBVs but heavy extended cabs and automatics put the hurt on your tank. My '86 was a long box single cab, 2.9, 5 speed with 3.45 gears and 215/75/15 tires... I got mid 20's regularly with that setup.

We went to some really remote places in Utah this last summer and found out that running low on fuel is not the most fun thing. As the crow flies we were probably only about 25 miles from a gas station but it was about 110 miles total round trip on the road, and the vast majority of that was under 10mph. Basically idling in 1st gear for hours on end. It's really eye opening - your fuel is almost better measured by gallons per hour instead of miles per gallon. I think I got something like 5mpg on that tank.

 

[sgtsandman]

+1 on the carrying fuel cans to extend range. The skid plates might help some but probably not enough to make a huge difference.

On the tires, LT tires often have higher rolling resistance than P-rated tires. How much of a mileage difference there is between the, I couldn't say. Probably 1-2 mpg at most. It might be something you might want to run an internet search on. I doubt the tire manufacturers will have much of anything on the subject. Just keep in mind the source you get the info from. Eco oriented sites are more than likely going to be anti anything that decreases mpg and may distort the information.

 

[gw33gp]

It is difficult to get better mpg in every circumstance. When I switched from 31" BFG AT tires to 31" Michelin LTX M/S tires, I got a couple mpg highway mileage improvement and about 1 city. Then I switched from 4.10 gears to 4.56 gears and my mileage dropped with the Michelin tires. I can get better highway mpg with my 33" BFG MT tires and 4.56 gears, but the city mpg is about the same.

Then again, the 31" Michelin tires with the 4.56 gears improved my towing mpg.

 

[09fx4guy]

From my experience, tires can have a decent effect on mileage. I would get between 19-20mpg with the stock Goodyear Wrangler RT/S tires (255/70R16), and when I switched to General Grabber AT2 (265/70R16), my highway mileage dropped to about 17-18 mpg. I had also added a Diablosport Trinity tuner, which may have dropped the mileage a bit, but the driveability of the truck is a bit better. I do notice a difference if I run regular or premium, getting slightly better mileage on premium.

If I were you, I would not bother with the full length skid plates. I had tinkered with the idea of doing something similar on the truck, but being in NJ, and the amount of salt that is used on the roads, I would be taking them off constantly to try and wash the salt off.

Roert42- When my truck is no longer my daily driver, I am going to look into that supercharger kit as well. From what I have read, the lifespan of the engine should not be reduced too much.

 

[JohnnyO]

Smokey Yunick says Hi.
The best bang for the buck to improve mpg is a cat-back exhaust. I had a Gibson cat-back, now a Flowmaster DBX on the Gibson pipes, if I keep it under 70 on a flat road I get 3 mpg better than the EPA highway rating. City mpg is no different.

Cat-back exhaust.
Fresh plugs and wires. I use NGK Iridium plugs and NAPA's best wires.
Fresh air and fuel filters. Ford says change them every 30k. I clean the K&N once a year and a new fuel filter every 30k.
Fresh synthetic lube in the axles and transfer case. Pro tip: Don't even try the front axle, just take it to the Valvoline Qwicky Lube where they do it with a machine. Old lube can get thick too, not always thin. In the transfer case use Mobil 1 ATF or Valvoline Synpower Transfer Case Lube.
Headers don't make any difference because the stock manifolds are already pretty good.
Nothing you do, and I mean nothing, will make a big difference.