So I completed a 95 12 v swap into my 78 F250 crewcab 4x4. I had the 47RH trans rebuilt and used the Dodge D70 rear. Has 3.54 gears & 315/75 tires. No fuel mods, 4" exhaust, BHAF, Billet single disc TC

Runs great unloaded. Put the 4k lb camper on it and it does ok going up the passes and on the freeway.

This weekend had the camper, car trailer, & my EB on the trailer. Probably hauling around 11K-12K lbs (not counting the truck). There are a couple of passes on the way to our destination.

When starting up the pass I give it some good throttle while in 3rd gear & TC locked up running about 2,500 rpm (no tach....) with about 12-15 boost. Pretty quickly it starts to get up to 1,200 egt so I keep backing off and slowing down until it about 1,800 rpm range and about 10 boost, unlock the TC and then it'll run up the pass about 25 mph, 2,700 rpm & 10 boost.......but with the TC unlocked then then trans temps go up. I can get up the pass and top out of 235 deg trans temp (sensor in stock location of front cooler line port).

Is that sound normal? I'm thinking it should pull a little better.

From what I can tell the stock tire size for a '95 Ram 4x4 was 245/75's, I'm now thinking that the tire size I'm using is making the difference on the pulling power. Thoughts?

 

It doesn't sound like it is lugging as 2000 to 2500 is a good range. All in all with the load you described and the grade sounds pretty steep. I would guess that the only way to get the pull on the hill better is to upgrade the trans cooler or get a bigger turbo.
I would say its working well for a stock 12 valve.
Any mods on the engine :fuel plate,injectors, turbo ect? and how long and steep of a grade is the pass?

 

For cooling I'm using the factory heat exchanger on the engine, an aftermarket stacked plate cooler in front and an auxiliary remote cooler with an electric fan. Once I lock up the converter it goes down to about 160-180 degrees

No mods to the engine besides the intake & exhaust. The grade is about 1,000' in 3.5 miles. The speed limit on the highway is 60 and there's a curve and pretty significant bump at the bottom so you can't really get a run at it.

 

I would think that your right about the tire size if you go smaller diameter it will raise the rpms. but if your like me i want big tires. Maybe its time to bomb that 12valve
a BD super B is next on my list. more air more cooling
I think alot of guys with the first gens are running like 63's or 64's check out some of the good info and sticky posts in the 5.9 12valve and 1st gen section.

 

The 47RH has a tall OD... plus, your tall tires and 3.54 ratio.

EDIT: nm.... now I see you have lockup 3rd