Best setup for towing/nontowing power and MPG.

[redtop_travis]

1994 Stock turbo IDI 7.3 with 3.55 ratio and 315/75/16's 260k miles on her

What RPM do I want at 70MPH so that I can tow my 6000 lbs camper and hold 70 MPH throught the hills and still have good MPG at unloaded daily driving. I'm working on gear or tire change to get this rig moving propperly. I have a calculator to tell me ratio or tire size needed but I need to know what RPM to shoot for.

 

[Devon Harley]

i would say 265 tires an around 2300 rpm

 

[FordGuy100]

E4OD or ZF5? Those tires are going to hurt you, especially with 3.55's. But, if you were to run in direct, it might actually work out pretty good rpm wise (with those tires direct at 70mph should be around 2300rpms).

 

[wmoguy]

E4OD or ZF5? Those tires are going to hurt you, especially with 3.55's. But, if you were to run in direct, it might actually work out pretty good rpm wise (with those tires direct at 70mph should be around 2300rpms).

If its a 94 idit it should be an auto, right?

But yea 2300-2500 rpm and she will tow real nice.

 

[redtop_travis]

Yes auto. So drop to a 265/75/16. Thanks

 

[FordGuy100]

If its a 94 idit it should be an auto, right?

But yea 2300-2500 rpm and she will tow real nice.

No, your thinking powerstroke. 94 powerstroke only got the ZF. The 94 IDI (T)'s got either the auto or manual. If you see a 94 with an auto, it has to be a IDI

 

[bike-maker]

I run the same size tires but with 4.10 gears, and in my opinion, the gear ratio is a perfect compromise between towing power / fuel mileage.
When I tow my 5er, 2300 rpm (roughly 70mph) is a decent cruise RPM, but for any kind of hill, I'm shifting down to 4th.
Unloaded it isn't nearly as sensitive to what RPM it's turning, but loaded down, it doesn't make good power unless it's at 2500RPM or higher. This may be partially due to the non WG turbo.

My previous truck had 35's and 3.55 gears but was a 1st gen powerstroke (it made just about the same amount of power at the same RPM as my IDI now does). It was great for going down the freeway, not so much for hauling the 5er.

 

[FordGuy100]

I always like 3rd gear in mine for towing. If I started dropping speed in direct, I could throw it in 3rd and give her hell. EGT's wouldnt get to hot, and I could gain speed at about half the rate as I lost speed in 4th. Plus the govenor in 3rd is 62ish mph for me, I feel like that isnt so slow that traffic will get to upset.

 

[bike-maker]

I only use 5th gear on the interstate. Every where else (55mph speed limit), I leave it in 4th.

 

[FordGuy100]

I only use 5th gear on the interstate. Every where else (55mph speed limit), I leave it in 4th.

Makes me want to move back to Oregon. So tired of the 75-80mph around here.

 

[redtop_travis]

I only have 4 gears. What is diect?

 

[92F350CC]

Makes me want to move back to Oregon. So tired of the 75-80mph around here.

55 mph on the highway would drive me insane. When I'm on the interstate, I live in the left lane.

 

[dmaxjoe]

I only have 4 gears. What is diect?

Direct would be 4th.

 

[kc0stp]

In an E40D auto direct (1:1) is 3rd... 4th is .71:1 on the T19 manual tranny direct is 4th

 

[towcat]

Makes me want to move back to Oregon. So tired of the 75-80mph around here.

that's all you're seeing in your part of TX? when I was rolling through Midland/Odessa, the minimum speed they were running was 90mph. Even the oilfield service semi rigs was running me down in the fast lane. Just viualize this....a KW with a grille so big they had to delete the 4 light headlight set and go to a 2 light system. Add monster floatation tires and a 25k front axle, and you have a rather intimidating presence. I felt uneasy in my CC dualie, I could only imagine what it would be like in a small can