Hey guys first post to this site. Im Adam and i have a 2004 f-150 with a 4.6 2v. Mods are K&N CAI, Diablo Sport programmer, and Flowmaster exhaust. It has pep but not enough for what im looking for. I have 3:55 no limted slip diff. I was thinking 4:10 with lockers would improve it alot. Its 2wd drive and does 0 to 60 about 8 secs flat on a cold day. Im gonna install some long tube headers shortly. Well anyways to the topic. Will 4:10 gears be a big improvement or will i barley notice anything and be better off going with 3:75? Thanks and ill post pics later on of my truck.

 

Heres what my truck looks like for now. Enjoy lol

 

Hi and welcome. First of no one makes longtube headers for the 4.6 2v in 04-08 trucks, but JBA out of San Diego makes a set of shorty headers for them. Second Ford put three different rear axles under these trucks depending on engine, 4.2 v6 and 4.6 v8 trucks got an 8.8" axle and 5.4 3v v8 got a 9.75" axle and the heavy duty payload option got a 10.25" axle with 7 lug wheels. The heavy duty trucks all have 5.4's and are either regular cabs w/8' bed or supercab w/8' bed.

The general rule on gear swaps is to go at least 2 steps in either direction or the difference you feel will not be worth the expense. Since you already have 3.55's, go to a 4.10 or a 4.30 gear.

 

If 2wd and looking for pep and bottom end power 4.30s get my vote.

 

4:10's sound good to me, unless you have a 33" or bigger tire 4"30's will be to tall and you'll lose your highway speed

 

3.55 to 4.10 = 15.5% difference
3.55 to 4.30 = 21.1% difference

If installing a locker too, I am assuming it means you either want to launch harder on the road or be more capable off road. Coming from a 5.4 owner, I would get all of the extra "oomph" I could without killing highway milage and still being able to have fun (on or off road).

What is you target place to have fun, on or off road? Plans for the future?

 

ok to answer your ? yes thier is long tube headers for a 4.6 2v over at pacesetter. To yetti i want to launch harder and have better acceleration from a stop. If you have any ideas on what else i can do thats simple im all ears

Now heres the headers http://www.summitracing.com/parts/PSM-72C2229/

 

i also have bigger tires just not to big to make it have that aggresive look

 

Sorry to burst your bubble but those headers will not fit. If you go to the pacesetters website, you will see they are listed to fit 4.6/5.4 in the 04-06 trucks, but it is wrong. the 4.6 is a 2v motor while the 5.4 is a 3v motor and they both have different exhaust flanges on the heads so those headers could not possibly fit both, they would fit one or the other. Turns out they fit the 5.4 3v. Someone bought a set when they first came out and they fit the 5.4 engine, so they are mislabeled by pacesetter and therefore by summit. So you are back to square one, sorry.

 

4.10's or 4.30's and a limited slip differential will do fine. In about another 6 months, Pacesetter will release their long tubes for the NBS 4.6.

 

dang 6 more months... That blows..

 

I went for 4.56s on my truck. The highway mileage will suffer but you will have a lot more power from a stop. I just drove to Vegas from here in San Jose CA and even though I averaged almost 85 mph the whole way, I still made 16 mpg with this gearing. When I had 3.55s I probably would have got 20 mpg on that run.