65+ Vehicle modifications for better fuel economy - EcoModder.com




100+ Hypermiling / ecodriving tips & tactics for better mpg - EcoModder.com




mine:




i get passed more times than i can count in a single day (it's not due to a lack of power,but a light foot) lol.but when she hauls so much at once,what's the hurry anyway i figure? more often than not,im going the local speed limit anyway.seems most folk don't follow the rules of the road anymore.i don't mind.shoot,i even pull to the side to help 'em on by most of the time.

i need to move by tool boxes outward so i can skirt between them over the wheels still.letting the airflow stumble over that opening is a big no no.
thinking about some of that cosmetic (it's just thin for looks) black diamond plate aluminum sheets to smooth out the stake sides.
i have a couple warped dually rims that cause some vibration i need to replace.those are not helping,and i plan on adding an inter cooler to the old school diesel to try and help efficiency a bit more there.
it's too bad the cummins swap is so costly,cus id love to have that straight 6 diesel.that would be a sweet boost i bet.way too much $ and fabrication.id never get my $ back during ownership.just the same,iv developed a soft spot for the old legend now.

forgot,i still need to swap to the turbo specific injection pump now that iv added a turbo,so i can have a better timing curve.
geeze.more than i thought to do,to this old gal still......always something.

 

Yeah notice I said MIGHT and CREW CAB, not all trucks are the same buddy. Did they specifcally do Fords from 80-96? Superduties have taller cabs then ours, older ones even shorter. Some have shallower windsheilds, some more time for the air flow above the cab to even out, etc.

The fact that the "bubble" exists is not proof that it's better, in fact it's proof of the low pressure "drag" behind the cab. What matters is it's effect compared to the effect of the pressures on an up tailgate. The taller the tailgate, lower the cab, longer the cab, shallower the windsheild, the more likely that at a given speed, overall drag will be reduced with the tailgate down.

 

Quote:[Another thought. On most modern cars, there are two engine temperature senders. One goes to your gauge on the dash. The other goes to your engine computer. If the one going to the computer is malfunctioning, it might cause your engine to eternally run in the warm up mode. This gives the engine a richer fuel mixture than it needs, thereby wasting gas.]:Quote

I didn't see this mentioned so here goes ... as mentioned above when the computer detects operating temp ... 192* it will stop adding more fuel to warm up. If your T-stat is not a 195* one your MPG will suffer... speaking from first hand knowledge !!! Every little bit helps ... Dave

 

The bubble behind the cab means that there is smooth airflow over the cab and that bubble, which means less drag--it directs the faster moving air over the tailgate. Low pressure drag is greatest when there is high turbulence behind the cab. Opening the tailgate causes that high turbulence because the air drops sharply behind the cab, which then causes a low pressure area over the rear of the truck.

Jason

 

Have you checked you speedometer calibration?

If you're 5mph off it could show up much as a 1 mpg
apparent loss.

I'd clean the throttle body, run injector cleaner, and
check timing.

 

That "bubble" behind the cab is an eddie created in large part by the air over the cab hitting the tailgate. And for the most part what you are saying is all true. But as you say "turbulence behind the cab" this turbulence lowers as the cab lowers amoung other things. And what do you think is behind the tailgate, I'll give you a hint turbulence. It's a trade off. It's what is better for that truck at that speed.

By your logic a taller tailgate will always net lower drag, this clearly isn't true. Or a canopy will lower drag, this isn't true either. What matters is the slope between the top of the cab and the top of the tailgate AND the area left behind the tailgate.

 

Just get a flatbed!

 

Ha! That's classic, I love it.

Yeah, I know how the airflow is thru the bed and that there's a tendency for stuff directly behind the cab to stay there. I use it to my advantage when hauling lightweight stuff like groceries from the store lol. I have owned enough trucks (3) to see that even an empty can will stay put, although it might float out of the bed and tumble around a bit before landing in the same spot.

I should have been clearer... on *my* 96 351 E4OD 3.55 geared 4x4 SuperCab shortbed, the tailgate up/down don't seem to make a difference. I'll go back and edit...

EDIT #2... was just thinkin... I have a full depth toolbox in the bed behind the cab. Which effectively reduces my bed to ~4 ft. Maybe that's why the tailgate doesn't make much of a difference? I drive with it up, regardless. Just to keep the airflow predictable if anything...

 

I've been told it was against the law to drive with the tailgate down. No tailgate is ok. This is probably a state to state thing, I believe this was VA where a friend of a friend got pulled over for it. I dont like to give them any reason to harass me.

 

Tailgate down also beats the snot out of the tailgate and the now un-supported bed sides as you go over bumps.

Jason

 

Plus it's real easy to lose the gate if it bounces just right, I have seen that happen to others several times and it's an expensive piece to replace.

 

its basically all city driving. and even with an automatic you want me to put it in neutral and down shift? i have probably a 200 pound toolbox full of stuff. i am going to get a tonneau cover eventually. but is it possible with a toolbox? and my tires i know dont help it at all. because it takes more gas to move that much tire.

 

Yeah it's still possible to put it in neutral and/or downshift with an automatic. It's actually easier because you don't have to push in the clutch. I drive the same way in my automatic shift car as I do with my manual shift truck. The theory is the same. Not sure why so many people have trouble grasping this theory. That's what the other positions on your gear selector are for.

Anyways, people seem to be getting off topic with the tailgate up/down discussion. The tailgate being up or down is not going to be the sole culprit of the OPs 8 MPG problem. It seems like a combination of things: The truck should be well tuned-up, check your timing, cap, rotor and spark plugs. Make sure your computer temperature sender is working. Make sure you don't have a fuel leak. Go easy on the throttle and coast when possible. If you are doing only city driving, you probably won't get better than 12 MPG with your setup. These trucks have fuel thirsty v8s and the aerodynamics of a brick. If your looking for better MPG than that, you should consider a newer/smaller truck or a car.

 

AMEN, BROTHER AMEN !!!

 

K & N air filters any good to help?