MPG Question RPM Qestion

[112motorsports]

I just bought an 99 F 350 with the 6 speed manual trans in it and I have a couple of questions for you. At 70 mph the truck seems wound the heck out. I am turning 2300 RPM according to my scan gauge, and getting 14 mpg. In town I am averaging 18-19mpg. My 03 Excursion 6.0 liter turns 2000 rpm at 80. I don't know what gears are in it but I need to do something about this. I don't like running the truck that hard on the interstate. Anyone who has any ideas I would appreciate them. Thanks again. BTW it is completely stock except for straight piped. Does straight piping affect the realibility by letting the turbo free spool? Thanks again.

[boostedh22a]

I just picked up an 00 F350 CC Dually PSD with a 6 speed and noticed the same thing. I'm about 23-2400 at 70 mph. My truck has a 4.10 rear. I don't really like turning the motor over that high, but the speed limit in my state on the highway is 70. Neither my old excursion or f250 (both autos) PSD's rev'd near that high on the interstate.

I'm curious as to whether or not it's fine to let the motor rev that high for extended periods of time? Short of MPG, are there any potential problems here? The only remedy I see is taller tires, different rear end gears, or simply just slow down.

Any help would be appreciated.

[112motorsports]

Anybody have any answers to either my question or boostedh22? Thanks again for any and all help.

[turbosuzuki]

i have a friend with a 01 f350 cc dually and it turns about 22-2300 @ 70. he has never had any motor troubles and he doesnt come under 80 most of the time.
we had a race in nc and we live in louisiana and pulled a 16ft trailer loaded with bikes and ran near 80 most of the way for 14 hours. i was like just slow down some and he looked at me like i was crazy lol.
maybe somebody will chime in with some knowledge. iam with you guys i wouldnt want to turn my motor like that for a period of time.

[Demo250]

I don't think it matters too much to be honest. Other than decreased economy everything should be fine. A few things have the potential to wear out faster I guess, but the engine should be perfectly fine. I know a guy with a lead foot and 4.10s that has around 270,000 trouble free miles and I'm sure he has that thing pretty wound out most of the time.

[usnavyad]

I ran 2500 rpm for 6 hours today at 81 mph is say I don't have 410s

[Dietoremain]

yup thats about right for 4.10's nothin you can do but change to 3.73's.. And these are diesel motors.. they are made to run in their rpm range... all day any day.. you wont hurt it.

[countryraised]

You will not hurt the engine, unless you are redlining it repeatedly or for extended time. They also used 4.30 and 4.68 gears with these engines and trannies in the 450/550's. My uncle has a 99 450 he runs all over the country with out ever a problem.

[112motorsports]

Any idea what RPM the engine will turn with the 3.73s in it at 75mph? Thank you for help and time.

[turbosuzuki]

Originally Posted by 112motorsports

Any idea what RPM the engine will turn with the 3.73s in it at 75mph? Thank you for help and time.

i know mine turns 2100 @ 70mph with 3.73,s. not sure about 75 i would run down the street to see but mines in the shop sorry