At least 4.56's. With the trailer you may be glad you went 4.88 though.

 

I bought a flood truck for cheap been rebuilding it ever since. I replaced most of it with the aftermarket on it instead of overpriced ford parts... I had a little left over and gave it a shot to try and lean it out, smelled rich on the exhaust side. maf was a stock size replacement.

 

Project is go 4.56 minimum, that will get you back to a stock 4.10 ratio, if u live where is very hilly terrain or high up in altitude I'd do 4.88. Don't be like me and have to spend money twice, especially when the rpm at highway speed isn't much different

 

If your truck had 265/75r16 tires stock which are 32" and 3.73 gears then you'll need a 4.08 year to get back to stock with 35" tires. If u had 4.10 gears you'll need 4.48 gears to get back to stock, problem is the 5.4 should have been offered with 4.10 and 4.30 only not a 3.73 gear, and with the OD in the trans you can go steeper to get maximum pulling power from the stArt. So again I'd go minimum 4.56 and like I said above 4.88 if it high altitude or hilly terrain or if you just want the correct power back. Me again I'd do 4.88 from the start cuz I'm hating doing it again for a second time

 

Most of the area around me is flat so I dont have to worry about that. I currently have 4.10 gears. Where are some good places to buy and what brands are recommended for a 4.88 gear??

 

Yukon gear makes some very nice products I would recommend a full kit to swap your gears. I have found their parts on amazon for cheaper too.

here is Yukons website,
https://www.yukongear.com/
to find a dealer enter you zip in here
https://www.yukongear.com/distlist.aspx

 

Hi guy's I also have a 1999 f-250 5.4l, I am looking to add more power to it. I am not too mechanic Incline. But I am starting too lurk around. I didn't want to ask questions before reading a bit.

If I am looking to add power to the truck.

I see ppl recommend y pipes? Why not H pipe is there a thread where I can read about this.

Right now running 295/75/16 in the summer, i was looking to lift the truck maybe 3 inches and go with bigger tires. Would it be ok to go with 305's ?

The truck will pull a small trailer 6x10 steel trailer ( Landscaping trailer.) nothing too heavy. for performance should i still upgrade the gear ? I am not even sure what I have in it at the moment. So i should go with 4.88 or that is just for pulling and not performance.

So changing the Air intake, adding a y to the truck changing gear and what else would improve the performance/ towing power ?

I will read even more.

 

Everyone recommends against the H or X pipe and simply a Y for increasing the most usable power in any RPM.

Gears are for both its more of a mechanical advantage the drive shaft would turn 4.88 times for the tire to make one full revolution no matter the size. We are just keeping it in perspective to the tire diameter. 305 is a metric measurement across the tire tread it is then used with an aspect ratio /75 which would equal 228.75 times that by for the inches gives 8.98 then times by two for the side wall above and below the rim then add 16 for the rim size. So your talking 33.9"x 11.98" r 16 depending on the wheel offset there may or may not be rubbing with a 2" / 2.5" front lift you can trim the fender a little if your not worried and run that size of a tire. I would recommend not installing a K&N oil type Air filter because it will coat the MAF sensor.

Depending on your budget maybe just swapping up to a v10 or a diesel or a different truck.

 

just for fun to figure out what your rpms would be take 3.14 times the diameter of your tire mine would be 31.7 then divide by 12 to get feet (8.294) take a mile divde it by that number 5280/8.294 = 636.604
now times this by your gear ratio and final drive ratio (4.88 * .71=3.46) this equals the rpm at 60mph (2209 rpms) (in third it would be 3106) if you drive as fast as I do your rpms would be at 2936 at 80 mph... ( 1.3333 * 2209) (at this point the truck is at 4141 rpms in third.)

here is the same thing with a 35" tire 3.14* 35= 109.9 109.9/12= 9.15' per tire revolution
1 mile(5280) / 9.15= 577.049 * (4.88*0.71=3.46) 1996 rpms at 60 mph (note in third it would be 2816 rpms) and at 80 the rpms would be 2662.12 (1996 * 1.33333 to get rpms at 80mph) (third = 3755 rpms).

 

My 4.30 gears are OEM but when I do my 4.88 I'm going with Yukon Gear. They are well know and make great products. Plus they have shims on the 10.5" pinion instead of a crush sleeve which is was stronger

 

Project if your ok with ur setup now and don't plan to go heavy towing or larger than a 35" tire go with 4.56 gears. That will get you back to your stock setup with 4.10 gear. I personally like the extra grunt of having a 4.30 gear stock so that's why I'm going 4.88 gears

 

[QUOTE=Jean-Guy Malette;16178968]Hi guy's I also have a 1999 f-250 5.4l, I am looking to add more power to it. I am not too mechanic Incline. But I am starting too lurk around. I didn't want to ask questions before reading a bit.

If I am looking to add power to the truck.

I see ppl recommend y pipes? Why not H pipe is there a thread where I can read about this.

Right now running 295/75/16 in the summer, i was looking to lift the truck maybe 3 inches and go with bigger tires. Would it be ok to go with 305's ?


-Forget the intake stock is more than what's needed
-your truck doesn't have the PI heads and if you like the truck and want to keep it I'd look into swapping in the newer PI heads
-a memeber with a 2008 just did a thread on a h-pipe setup and he's posted before and after results and it seemed to really help the 5.4 motor. When I get done my lift/wheels/tires I will be doing a h-pipe onto my 5.4 and see how it does. Oh and a x-pipe is for high rpm power not low end which our trucks need
- your tire now and after with 305 are not much larger than 33" and if ur fine with the way the truck does pulling that small trailer I'd leave her alone. If u plan on 305 and want power and you stay at a 305 tire save the money and get 4.56 gears

 

To put in the 5star y pipe on you don't have to take the whole factory y pipe off to weld properly the new y pipe on correct?

 

right from 5 stars performance site :
It is very easy to install. Just cut the old Y Pipe out and weld the new performance Y Pipe in. It comes with a coupler for easy install.

http://5startuning.com/product/1999-...00al-su9900al/

 

I saw that, I just didn't know cause there is no written directions. I'm getting it done at an exhaust shop.