MPG question

[bconnaway]

So over the christmas break i had several changes on my truck. I put in a 2.5" leveling kit, a 1.5" add-a-leaf, 275/65-18 BFG all terrains, and my 89 custom performance tune got uploaded. Ive been running this set-up now for about 2 weeks and noticed my MPG has dropped about 4ish MPG... I expected a little bit of a drop, but this seems a little bit steep?

[Longshot270]

Well the new tires dont help but I did notice a drop in highway mileage after I put a 2.5" leveling kit on. I used to be able to get up to 20-22 @ 55 mph but the highest I've seen is 17-19. I'll be taking that same trip again soon to see how much the kit impacts. (cold weather wont help accuracy but oh well)

BTW, how much did those tires cost? I've got 17's but I'm kind of wanting a ball park because I cant get a solid price from anyone. They are getting good at nickle and diming over here. Oh and where'd ya go? Austin is only a short drive for me.

[Jackpine]

Originally Posted by longshot270

Well the new tires dont help but I did notice a drop in highway mileage after I put a 2.5" leveling kit on. I used to be able to get up to 20-22 @ 55 mph but the highest I've seen is 17-19. I'll be taking that same trip again soon to see how much the kit impacts. (cold weather wont help accuracy but oh well)

BTW, how much did those tires cost? I've got 17's but I'm kind of wanting a ball park because I cant get a solid price from anyone. They are getting good at nickle and diming over here. Oh and where'd ya go? Austin is only a short drive for me.

I wonder if the "leveling" causes more turbulence (hence more drag) under the vehicle? I've seen lots of threads that complain about lowering the rear causing a drop in mileage. I can't think of any other reason. Maybe Ford engineered it right with the front end "dip"?

- Jack

[Longshot270]

Originally Posted by JackandJanet

I wonder if the "leveling" causes more turbulence (hence more drag) under the vehicle? I've seen lots of threads that complain about lowering the rear causing a drop in mileage. I can't think of any other reason. Maybe Ford engineered it right with the front end "dip"?

- Jack

I'm sure lifting the front causes more turbulence but I never considered lowering the back would too. Now I'm really glad I didn't go that direction after hearing that.

I always thought that ford had the front lower for hauling. I've noticed that the first few inches in the back would go quick but once it gets close to level the rate of change slows down.

Haha I wonder if adding plates or something to the bottom would make a difference. They could be lightweigh and thin on most areas but be reinforced only where they are most likely to come into contact with something.

[88Racing]

Originally Posted by bconnaway

So over the christmas break i had several changes on my truck. I put in a 2.5" leveling kit, a 1.5" add-a-leaf, 275/65-18 BFG all terrains, and my 89 custom performance tune got uploaded. Ive been running this set-up now for about 2 weeks and noticed my MPG has dropped about 4ish MPG... I expected a little bit of a drop, but this seems a little bit steep?

Lots of things to factor in?
Winterized gas
Bad gas
Proper air psi
Air filter clean
Fuel filter clean
Spark plugs last changed
Lift/level kits
Oversized tires

[bconnaway]

i change my oil every 3000 miles and that wasnt too long ago. Just changed my fuel filter. Bought my CAI new a couple months ago so it should still be pretty clean. Spark plugs changed around 3000 miles ago. Always monitor my tire psi. new tires arent that much bigger than my old ones: 275-65/18 compared to 265-65/18. So that made me think either possibly something strange going on with my custom tune or hopefully its just being caused by this winter gas.

[bconnaway]

Originally Posted by longshot270

BTW, how much did those tires cost? I've got 17's but I'm kind of wanting a ball park because I cant get a solid price from anyone. They are getting good at nickle and diming over here. Oh and where'd ya go? Austin is only a short drive for me.

i ended up buying mine from a Discount Tire down in Houston. The whole set cost me around $1150 which included a warranty (figured if i was spending this much on tires, another $100 or so just in case something happens...). Probably could have gotten a little bit better deal from some shady shops around there, but having the warranty and free rotations and balances for the life of the tires? i figure its worth it.

[Longshot270]

Originally Posted by bconnaway

i ended up buying mine from a Discount Tire down in Houston. The whole set cost me around $1150 which included a warranty (figured if i was spending this much on tires, another $100 or so just in case something happens...). Probably could have gotten a little bit better deal from some shady shops around there, but having the warranty and free rotations and balances for the life of the tires? i figure its worth it.

Haha gotcha. That was a good idea to get them in Houston because I've had trouble with the Discount Tires in Austin.

[88Racing]

$200 ea for install mount and balance up here.
So $800 plus 6% sales=$850 approx

[Longshot270]

I promised earlier that next time I took the route that gives me the best mileage I would keep an eye on the AVG MPG. Here is a basic description of the trip. The total mileage is 40, first 10 are a rough windy road, then it is about 15 miles of strait worn roads.(55 mph average) The last parts are 10 miles of highway followed by 5 miles of city. (75-85 mph and then 0 with some 45) The route also has a total change of 80 or so feet in altitude but it is mostly going up and down hills. I also had to push through a good breeze that hit the front passenger corner most of the time.
Well now you have a general idea of the route so here are the results.

On the first half I got up to 22 but mostly it stayed around 21.7
Then on the highway going 85 it still didn't drop below 21. Hit the city and it fell to 19.9/20.

I will admit that I did have to drive smart with the pedal to get those numbers though. I didn't have to drive like there was an egg between me and the pedal but I did let my momentum bring me up hills and around corners when I could. I also reprogrammed the truck to shift lower in the upper gears (but only 3&4) and lowered 4th gear TC -10. I used my custom 87 as my baseline. (That tune is still full of suprises.)

I believe that the gotts mod, lowered shifting/locking and cold weather played a part because those numbers were pretty much a record. In the picture you can see my truck isn't the most aerodynamic vehicle in the world with a grill guard, level kit and that cb antenna that causes a suprising amount of drag. I also had 2 mountain bikes, an ice chest and a potted plant.
...the plant and frozen steaks must have been pedaling when I wasn't looking.