I believe I already know the answer to this, but I figured I'd ask anyway just in case. Is there anything that can be done that actually improves the fuel economy of the straight 6? Best I can tell the truck gets about 15.5 MPG, doesn't matter if I'm driving Ms. Daisy or if I'm driving with my foot planted through the radiator. The only thing that affects fuel economy is to tow something, which actually has the expected negative impact.

From all the research I've done, this is a pretty typical characteristic of the I-6. So, being said, has anybody ever actually made a noticable improvement on economy?

Thoughts on all of these products:

K&N air filter or complete cold air intake
MSD Ignition & Coil
Long Tube Headers / No Cats / Freeflowing Exhaust
Tonneau Cover

I'm relatively new to this truck from a modification standpoint, but I do know enough about cars from my other experience to know that the only one of these that might really make a difference is the tonneau cover, and even that is questionable.

Thoughts?

 

I've heard several claims of better mileage, but I've never actually seen any. Any money you spend on parts to improve the mileage will take a good 20+ years to pay for itself. lol.

However, I can tell you right now that installing a K&N FIPK will make your truck much more fun to drive!

 

Yeah that's kinda what I figured. I was looking at the K&N setup but it's awfully pretty dang expensive. I suppose the plain K&N air filter probably doesn't do much of anything, the factory airbox is more responsive than the filter?

Curious, you list comp cams and edelbrock as some brands in your mods. What products do you have from these companies, how much power did they give you, and how much did that hurt your fuel economy?

 

The drop in is a complete waste of money, unless you're doing it so you never have to buy another filter again. You won't gain any more power or gas mileage than you would with a paper drop in.

The FIPK has mixed results with F-150 owners because most have a V8, and it doesn't do much for them. The 4.9L, however, absolutely loves it! I was blown away by what an improvement it made in my truck, especially on uphill grades! I don't know if my mileage got better or not, because that FIPK really woke up my truck, and made it fun to drive (which never helps mileage. lol).


I had a Comp Cams Vacuum Canister left over from my nitrous injected Buick that I installed in the truck. I learned a long time ago that it sucks when your power brakes fail because your engine stalled, killing the vacuum supply. It didn't alter power or gas mileage.

I also have an Edelbrock Performer RPM cat-back exhaust on my truck, which helped the mileage slightly, increased my manifold vacuum, and made the truck sound great. People are shocked when they discover I have a straight six, but it's not obnoxiously loud.

Another item that really made a big difference, at least as far as power goes, was a JET ECM chip. I had heard all kinds of crap about them, but they were the only ones (at the time) that had a chip for my truck in stock, so I gave them a shot. It made a big improvement, and combined with the FIPK, had me beating stock V8's fairly easily. Unfortunately, it developed a problem after a few years, but it came with a lifetime replacement warranty, so I got another new one for free.

Your best bet for better mileage is to keep the engine tuned, and fill your tires to their upper limit with air.

 

Yeah I have a '92 Corvette that saw an improvement with a stock K&N filter in a modified airbox, BUT it only saw a difference after the car was otherwise heavily modfied and needed the air.

As for the performance chips, I don't know about Jet, but I know I'll never spend money on a hypertech. I've got everything I need to tune my own computer for the Vette, so I decided to "take apart" a hypertech chip that somebody handed me.

For something like $250 all the chip did for the guy was to change the torque converter lockup, change the fan speed, and REMOVE the 5800 RPM rev limiter. If his transmission ever failed to shift, it would have destroyed his engine. There were absolutely no changes to the timing or fuel maps!

 

My truck does need a new exhaust system. The muffler is intact but the tailpipe south of it is completely gone. I was looking at Edelbrock and they list their cat-back for that truck for the v8's only. Does it bolt up or does it require some fabricating / welding?

 

Get the kit for a 5.0L V8. It fits perfectly.

 

That's what I wanted to hear. I really like the look of the dual side tips.... but I like the dual rear outlet as well.

 

Ford knew they could save some money by designing the 5.0L and 4.9L exhaust so that from the cat back, they were identical.

The tips are a personal preference. I like the side exit, but shotgun pipes look good, too.

 

Interesting information this morning in the fuel economy department. My numbers for economy were based off of what my dad ever got out of the truck and what my friend David got out of the two he had owned.

I finally emptied my front tank this morning at 286.5 miles on it. I swapped over to the rear and drove into the nearest gas station to fill it up while gas is actually relatively cheap. I put 17.001 gallons in (funny how you can do that on a 16.5 gallon tank). Do the math and that's 16.85 MPG!

That's really not that bad for a full size truck driving around town, I'll take it!