Considering selling 7.3 "X" & Buying 2006 6.0 F 350

[dlonno]

I get 16 hwy and 14 in town with 4.30's and 37" tires.

 

[bushpilot]

I honestly don't know when that changed. I wouldn't mind 3.55 either, anything much higher than that is overkill for me because all I pull is travel trailers.

I did a 4:10 to 3.08 swap in my '90 dually a couple years ago as a fuel milage experiment. Gears and installation kit cost me about $325 and a buddy of mine that owned a 4x4 shop at the time owed me a favor so he installed them for free.

Was able to get almost an extra 5 mpg on the highway cruising 62-63 mph. did about 3 mpg better in the city but performance suffered greatly on a N/A 7.3 IDI engine. I gave the guy that bought it from me the original 4.10 gears but he ended up swapping in 3.73 and put a turbo on it.

i agree completely....the 3.55 would STILL be fine for me too...towing
cars etc mostly.

the reality is ours is mostly an interstate dog/people hauler...so the 3.08
is VERY attractive to me....another 5mpg would mean another 190miles
per TANK...putting me near 900mi per tank (w/out much load other than
people & crap in the bed)

 

[Maxtor]

Hey Bush;

I would not recommend the 3.08 gears, because unless you do 90 mph, the rpms would be to low in the torque band. At 90 mph, drag would reduce any mpg improvements that you would have made. At the legal speed limit, you would be just above an idle in overdrive.

 

[GO BIG]

I was actually thinking of putting 4.10s in to help with the towing and if Dogman can get 21 mpg with 4.30s then mayb ei will have to look into it.

 

[Dogman]

GO BIG, I have a chart someware that has a break down of hp, RPM, to gear to tire size for max horse power, and max mileage. I'll see if I can post it.

 

[GO BIG]

Check out this site. Works pretty good when you put in the transmission ratios.

http://www.f-body.org/gears/

Cost wouldn't justify the gear change. Final answer.