hey guys i got a 2002 f250 v10 with 373 gears, i have a 6in lift and 36x15.50 tires, mikes 5 star tune, no cats and glasspack exhaust, etc. i wanna regear to get more power but do not wanna hurt mpg maybe improve it if possible. i was looking at 4.30 or maybe 4.56 but like i said dont wanna kill the mpg i have now. any help would be appreciated thanks

 

I know it goes against what many of us have thought for years, but the V10 actually gets better mileage with a lower gear ratio. The 3.73 gears, according to many, should never have been installed in the V10 because it won't allow the engine to run at high enough RPM to be efficient or make power. My V10 with 4.30 gears gets better MPG (see my sig below) than my buddy who has 3.73 gears. In your case, you should go with 4.56 or even better, 4.88 gears to get you into the optimal RPM for MPG and power. You will actually improve your mileage and power by doing so.
By the way, with 4.30 gears and 34" tires I am turning 2,000 RPM at 55 MPH and 2,300 RPM at 65 MPH, netting 14-15 MPG on the highway.

 

thanks man, i think im going to lean towards 456, 14 to 15 mpg on highway is way better than what im getting now

 

I don't know that your MPG will be that high. I get that MPG on long trips with no load, no hills, and driving like a grandma going to bingo.

I also have the mods listed in my sig below and use Lucas Fuel Treatment on a regular basis.

 

but you do think that going to 456 from 373 will not only improve power but also some mpg?

 

Yes it will

Denny

 

Best place to get 4.30 gears from?

 

I would go no taller than 4.88 gears.

 

thanks, i plan on going 4.56, if you guys dont mind what does it usually run to get gears installed?

 

Good choice on the gears

 

4.56 for sure. I also own www.lonestaraxle.com Give me a call I can get you a pretty good deal on gears. 713-299-6453.

 

jump to 4:88's...

if your going inside teh pumpkins, nows teh time to not only regain the lost power from those big tires but actualy gain some power to the ground...

4:56 will put you more or less right about were it would be stock with stock tiny tires, but the jump to 4:88s will gain you power to the ground..

and your trans will thank you for it to.

 

I run 4.88's in my 99 v10 and it turns 2300 at 65. 4.88 prob a little much for 36's.

 

When I bought my truck it came with the 3.73's and I towed a 30'TT and it was fine on the flats, but was a dog in the mountains. Then I switched from the 3.73's to the 4.30's and upgraded to a 34' 5th. The truck tows like a truck now. The 3.73's are a joke for a truck like the F250/350.

My mileage didn't changed that much towing I get between 7.5 and 9.5 mpg depending on the grades. In the city I get around 10 mpg and on the freeway 14 to 15.

My advice if you do a bunch of towing go with the 4.56's. If I had it to do over again I would choose the 4.56 or 4.88. The 4.30's work great for me and I think its a good all around gear for city driving and towing.

 

I have a 99 f250 V-10 SD, 8" lift w/ 37's. Whats the best gear ratio for that setup and can I do only the rear for now, if I don't use 4 wheel drive?