Considering getting V10 and was curious as to how many RPMs engine turns at 60 in overdrive. Currently have 92 460 and love the fact that 1800 gets me 60. Please include rear ratio. Thanks

 

Can't remember what it turns at 60 as I usually drive 65 to 70 on the highway. At 65 it's at 1700/1800 and at 70 it runs at 1900/2000.

It has 3.73 axle gears. Found if I keep the rpms at or under 2000 as much as possible I get an extra 1 to 2 mpg per tank.

 

60mph in OD (.72:1 with the 4R100, ZF-6 & .71:1 with the 5R110)

w/3.73:1=1690rpm.

w/4.30=1948

w/4.10=1857

Thess numbers assume stock 265/75R16D tires and the 4R100 or ZF-6.

Straight from my Super Duty FAQ

 

Monsta, thanks for those numbers. They're interesting. It doesn't matter, though, what size tires you have. The speedometer doesn't measure ground speed, but the speed of the drivetrain.

 

Off topic
I agree and disagree. I am sure the poster meant actual speed, not indicated speed.

We all know taller tires will move the truck further each revolution, therefore changing the realized final drive, lowering the engine speed required achieve any given speed. If the speedometer is recalibrated for a taller tire, making indicated speed equate to actual speed, the engine will turn slower at 60 with a taller rear tire than stock.

Back on topic:
I am at 1900 at 70 with 3.73 gears and stock everything.

 

Can you recalibrate a speedometer with a stick? If not, it's not the indicated speed that changes, but the ground speed. I know with the auto, the speedo can be changed. I'm running about 2050 rpm at 70 mph indicated in 5th gear. With 285/75/16s I'm actually going about 71.5mph.

 

That's pretty close. I am not sure that you will be able to do better than that no matter what you do. That's only .02% off.

I would check with a speedo shop, but I am quite sure they have an adapter for any transmission.

 

Thanks for the info it was just what I wanted to hear. I guess I figure engine will last longer if it 's strong enough to do it's job at a nice moderate RPM.

 

That would be incorrect. Engine speed and final drive ratio are inexplicably linked. The tires are a part of the final drive ratio equation.

Keep in mind that the OD ratio on your ZF-5 is different than the 4R100 or ZF-6. (.76 to .72) ...If you are using the above mathmatical equations for comparison.

 

Checked my F-350, V-10, 6-speed, with the 4:30 LS, at 60 mph its 2000 rpm on the tach and in OD.

Later,,,,,,,,,,,,,,Mark

 

I checked with Ford. Within limits Ford can change the speedo calibration for you. It appears the PCM has a tire size value in it that can be changed. If you go to a taller tire, Ford can update the PCM to compenste for the different than stock tire size.

 

I just had my dealer calibtate my speedometer due to tire size increase to 315x75x16's. Normally charges $75 for this but since I bought the truck there and worked this into the purchase price, he did it for free, just this once.

 

I have a 2004 F250 w/3.73:1 , 4sp Auto , 285/75/16.
1650 RPM @ 60 MPH. 13.5 MPG.
Anything over that, the MPG goes down to 10-11.

 

F250 SD 4.3axle, V10. OD 60mph 2000rpm, 3rd gear 60mph 3000rpm. It drives this way loaded or unloaded. I think this where it should run. Pull a 9000# trailer in 3rd 3000rpm at 60mph so I'm satisfied.

Cheers

 

My 2001 F-250 runs 70 mph at 2050 rpm. 3.73 with stock tires and weighing in at 6750 lbs.
15 mpg average on a long haul.