Transmission,,which is better overdrive or locking tourqe converter?

also can i make an external overdrive unit out of an old transfercase,,,,,i have to do something at 55mph im doing 22rpm and im watching the gas gage drop i would like to get my rpm down to like say1,this is a ford f-250 5 speed manual,mazda trans,it had the 3 speed auto but swaped it out for the 5 speed stick that brought my rpm down about a 1,from 3 to like 22.im thinking external overdrive would bring my rpm down.ideally id like to be doing 70 mph and in 5 gear doing 1rpm,now that would be great.external overdrive units are so expensive so was maby thinking i can build my own out of a transfercase so let me no what you(the world)thinks,thank you!.Transmission,,which is better overdrive or locking tourqe converter?
If you try and run this elephant of a beast at 1,000 RPM's in 5th gear, the engine will be begging for mercy, and sucking gas like crazy. You are probably not going to get any better than what you are getting now. The 250 is a large truck, and 2,200 Rpm's is pushing it at cruise, I would not want to go any lower than that. That is a lot of weight to move and the engine will work harder if under a load all of the time trying to pull it. The lower RPM's will lower the power output of the engine, making it work harder to pull the weight of the truck. As far as building your overdrive unit out of a transfer case, you would have better luck swapping your engine out for a 7.3 liter diesel, it would be easier than what you are suggesting, and save you fuel and maintenance costs in the long run.
Dude, you are all over the place on this question. Forget building your own overdrive -- if you are THAT talented you can afford to buy more gas or a new car. Put bigger tires on the truck -- it's a cheap way to lower RPM's though the fuel savings will be nominal. If you REALLY feel energetic, you can swap rear diff. assys for different gearing.Transmission,,which is better overdrive or locking tourqe converter?
i have a clutch type converter with overdrive.1 good thing about overdrive is you save gas but you lose power on a hill.Transmission,,which is better overdrive or locking tourqe converter?
Man IF MY CAR ran at "22" R.P.M at 55 MPH, GEEEEEEEEEESSSH, LIKE 238.6 miles to the gallon!



but then again my engine would need to be a 12 cylinder diesel out of a antique Cruise liner or something to get down to the 22 rpm area, hhhhhhmmmmmmmm?



I like what the ford man says above me, yepers
you are gonna burn up your motor if you lug it like that.



It's not rpm that uses your gas it's LOAD and you are dropping rpm but adding alot more LOAD.



At what RPM does your motor make it most torque. ok that is where it is most effecient.

So that is the rpm range you want to be in at 70 mph for the very best fuel economy.