woah wth

[cody994x4]

unleashedford, im not sure abt mpg's but i know if you were to re-gear you would have alot of restored power. the minimum reccommendation, as far as ive ever heard is at least 3.73's with 35's, 4.10 or 4.56 would be better. you will be able to get going alot easier and put your rpms back around the powerband range. im curious to what your rpms are at say 70mph with the 35ers

interesting how this plays into the mpg equation though, your tires are lowering your rpms thus saving gas...

for economy you might wanna stay where you are but im pretty sure your asking alot out of a smaller ring/pinion.

you might wanna research restored power vs economy if you were to re-gear.

[Jackpine]

Originally Posted by cody994x4

unleashedford, im not sure abt mpg's but i know if you were to re-gear you would have alot of restored power. the minimum reccommendation, as far as ive ever heard is at least 3.73's with 35's, 4.10 or 4.56 would be better. you will be able to get going alot easier and put your rpms back around the powerband range. im curious to what your rpms are at say 70mph with the 35ers

interesting how this plays into the mpg equation though, your tires are lowering your rpms thus saving gas...

for economy you might wanna stay where you are but im pretty sure your asking alot out of a smaller ring/pinion.

you might wanna research restored power vs economy if you were to re-gear.

I've "bolded" the part of your response that is most significant. The lower RPM's CAN save gas, but you've got to get there from a standing start. In his case, the bigger feet make his engine work a lot harder getting it up to speed, due to several causes:

1. A reduced "mechanical advantage" (lower effective gear ratio) due to the larger radius tires.
2. More mass to get spinning from a standstill - Newton's third law still applies.
3. More wind resistance (a minor effect, but still there).

Once at highway speeds, you're still not home free because:

1. The bigger feet weigh more and have more wind resistance - so, more fuel needed to keep them rolling.
2. They probably have more "rolling resistance" (skin friction effect with the road) so it takes more power to keep them moving.
3. Even though the engine RPMs are lower, the torque output of the engine has to be higher due to the reduced mechanical advantage. That torque has to come from somewhere, and it can only be additional fuel per cylinder charge.

So, the whole concept of power vs economy is a very complicated tradeoff. Ford's engineers actually tried to get a good compromise at the plant. It CAN be improved, but I suspect it can much more easily be made worse.

- Jack

[Longshot270]

Haha Jack, just as I was about to say something smart you steal my lightning.
True the lower rpm would suggest better mileage but the other factor in fuel economy is engine load. A higher engine load can hurt your economy more than a slightly higher rpm. I actually tested it about a month ago to show a friend of mine who was thinking the same thing except he was completely convinced that putting 35s on a chevy colorado with an I4 and highway gears would get him killer mileage because of the final drive ratio.
Here is the thread that has the graphs from compiling multiple recordings using the gryphon's data log feature.
http://forum.gopowerhungry.com/conve...t-mileage.html

It is easier to turn a gear twice as many times with smaller tires than to turn a heavy set of tires for all of (and more) factors that Jack has just mentioned.

[cody994x4]

i agree jack i think it can much more easily be made worse. if he were to re-gear to lower, he would loose mpgs correct???
maybe in this case a fair trade off would be to go with 3.73's...but idk if id spend that kind of money to only go a tad lower.

another good point you made was wind drag. when i went from stock 31's to the 33's i noticed this...i cant look at girls driving down the road as long as i used to cause ill be in the next lane. not much of a big deal but on really windy days it is def. noticable.

also isnt it a fact that things in motion tend to stay in motion? i guess weight rules here. this is one reason i want to get off of my stock steel wheels. w 33's and the steel wheels it is hard on my brakes, esp. when towing

still curious as to what the 'ideal' set-up would be for his application...

[Longshot270]

Originally Posted by cody994x4

i agree jack i think it can much more easily be made worse. if he were to re-gear to lower, he would loose mpgs correct???
maybe in this case a fair trade off would be to go with 3.73's...but idk if id spend that kind of money to only go a tad lower.

Depends on your driving. You may get better city mileage because stop and go traffic will be easier on the engine and transmission because of the trade for torque. The highway mileage is what will probably suffer.

another good point you made was wind drag. when i went from stock 31's to the 33's i noticed this...i cant look at girls driving down the road as long as i used to cause ill be in the next lane. not much of a big deal but on really windy days it is def. noticable.



also isnt it a fact that things in motion tend to stay in motion? i guess weight rules here. this is one reason i want to get off of my stock steel wheels. w 33's and the steel wheels it is hard on my brakes, esp. when towing

Yep, that is one of Newton's laws. Call me crazy but when I got a set of alloy rims I could have sworn that the truck accelerated a little faster.

still curious as to what the 'ideal' set-up would be for his application...
I'm just making a guesstimate based off of the pegasus gear ratio calculator and some of the common gear ratios I've seen online.
I think a good highway gear would be around a 4.56 and a good city gear would be a little higher.

In blue...

[Unleashedford]

woah im gone for 1 day and a lot of conversation goes on lol

but when im at about 70mph my rpm is also at 2000 maybe like 1950 or 1900

and this whole re-gear thing, do i do it from the gryphon settings or do i need to open up the rear differential and chance the gears in there?

[88Racing]

Originally Posted by Unleashedford

woah im gone for 1 day and a lot of conversation goes on lol

but when im at about 70mph my rpm is also at 2000 maybe like 1950 or 1900

and this whole re-gear thing, do i do it from the gryphon settingsor do i need to open up the rear differential and chance the gears in there?

Both
or the custom tunes can be set to the new gear.

[Longshot270]

Originally Posted by Unleashedford

but when im at about 70mph my rpm is also at 2000 maybe like 1950 or 1900

and this whole re-gear thing, do i do it from the gryphon settings or do i need to open up the rear differential and chance the gears in there?

To regear you have to physically change the axle gears. Then, like 88Racing said, you go into the gryphon settings and put in the new gear ratio so that the pcm will keep the shifts where they need to be. I'm not sure if your gear ratio or something is set right because if your 70 mph rpm sits around 2000 and you have the 3.55 differential then your rolling on 29-30's not 35s. Is your speedometer/odometer accurate? My truck has stock tires (with about 6.5% squish) and 3.55 LS axle.

But if that is what your getting then just leave the physical gears alone. About 2000 rpm @ 70mph is pretty much stock.

[Unleashedford]

i think my speed meter is off my like 5-10mph and im sure i have 35's on my truck lol

[88Racing]

To understand the custom option menu read this.
http://forum.gopowerhungry.com/faqs-....html#post9248
Your tires 285/55R22
Calculate to 2740mm
With 3.5% squish taken out is.
(2644mm) try this number.
The gryphon uses millimeters.
Also make sure to use the right gear ratio.
Hope this helps.

Peace!