MPG question
 

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?

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. :thumbsup:

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.

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

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.

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.

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

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 :hehe: 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:disbelief: :yikes2:
Then on the highway going 85 it still didn't drop below 21. Hit the city and it fell to 19.9/20. :disbelief:

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.:crazy:)

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. :hehe:

:smiley_roll1:

That $**** is funny! High 5!

dang. the perks of having a reg cab... i used to get 18 when i would baby it. now i get 14 or so. :throwup:

Do you guys recalibrate your speedometer when using taller tires?

Reason I as is because with the larger tires you are actually traveling farther than what your speedometer shows, thus lowering your calculated fuel mileage.


Its is surprising how far off they can be. I had changed from the stock 31'' to 33'' , and during a fairly recent road trip(7,800k) I kept a very close eye on actual miles traveled via mile markers, and my trip counter. Now keep in mind I would watch this every day of the trip, and kept a log on it, and it would consistently show that every 10 miles my trip would only count 9 miles. Doesn't sound like much but over a tank of fuel, roughly 350 miles(on the trip), I actually traveled 385. Figure the mileage on 26 gallons, which would show 13.5 mpg, when actually it was closer to 15mpg.


Just an idea........

Well they probably aren't that far apart in weight when you consider I have the brush guard, stereo/radio equipment and a fully loaded tool box and your truck is probably naked. :hehe: Trucks are heavy, I just used it to my advantage. Instead of powering up hills and around corners I would just let it coast and let the weight pull it through (until it got below 5 mph of my regular speed). Like I said, there was a lot of fancy pedal work involved. I need to see if I can get it weighed because I've just been going on estimates. I'm guessing 52-5300# for my truck (4800# curb + 150# grill guard + 100# stereo/radio equip + 200plus# tool box...that sucker is heavy when fully loaded like it is) and I've seen numbers for your truck that range from 5200 for 2wd to 5600 for 4wd. But the road I took has a magical effect on mileage.

And 907dave makes a good point. Until you have your tire size dialed in, your mileage is going to be off. It will be better if the number is smaller and worse if the number is larger. If you dont have a GPS or some decently spaced road markers just go to a parking lot with a marker. Mark the tire and the street, roll one full turn and get a tape measure to measure. The measurement will probably be really close if you drove for more than 5 miles to warm the tires up. It would be funny if driving to a parking lot could increase your mileage.:hehe:

Discount Tire
 

Guys try Discount tire in College Station. The manager there is Mike Macalese and he is freaking awesome. Its a short drive from houston and or austin and the service is awesome! well at least it was a year ago. I bought me BF goodrich ats for 840.00 with warrenty! 275 75/17 load range d! Just work with them and they will bend over backwards for ya! IDK if you could get a deal like I did but it is worth the try!