So I was building a 2011 superduty on the ford website the other day and noticed that the 6.7L diesel only comes with a 3.31 gear ratio option. Hmmm, I know they got the 6 speed trans and a lot of grunt in that 6.7L but 3.31 really? Is this where their big fuel mileage increase with the 2011s is coming from?

 

Just went through the build process myself. You can get a 3.55 locking rear with the 6.7, but not 3.73 or 4.10. My guess is possibly with all that torque that it would require to high an RPM on the engine with those ratios.

 

Yeah I'm not an expert, but I would guess that the 6.7L diesel with 800lb-ft of torque at 1600 RPM doesn't need to be geared as low as the 6.2L gas which has 405lb-ft @ 4500 RPM

http://www.fordvehicles.com/trucks/s...ations/engine/

 

Also look at the RPMs. Peak hp and torque is at half the RPMs of the gasser.

 

Thats wierd. You can get almost any ratio in the 350. hmmm..

 

Just tried it with the 350. Only 3.31 and 3.55 available with the diesel.

 

My point exactly

 

the diesels don't need to be geared as low. they'll spin up too fast.

 

Put some 35's on and they will really be screwed!

 

Not with 800ftlbs...You dont really NEED the low gear

 

Yeah your right, my bad. But you can get 3.73 in the 350 if you go with the DRW f350.

 

with the lower ratio first gear it's like 4.10's on the "older trucks"