I was towing my exploder on a trailer with my 85 E350 van and it performed great on the flat land and minor hills. My question is when taking on substantial hills should I heave the van in drive at 40 to 45mph or drop it to second and kick up the RPMs? I don't have my GV hooked up so I can't split gears yet.

 

I would think if you can't get above 40/45 mph up hill, you should be in 2nd gear on a C6.

 

I always assume that if you drop it a gear and get more power, the lower gear is where you want to be. If you drop it a gear and /lose/ power, the higher gear is where you want to be.

Part of your problem is that being N/A, you start losing torque above about 2000 RPM. You still gain horsepower, but not very much.

The real solution to your problem? Add a turbo. You won't have to worry about this sort of problem any more because the torque peak goes from 2000 to about 2600, and you should end up with a nice wide power band in the 2200-3000 range or so.
(Note: Banks has some nice graphs: Banks Power | 83-93 Ford - 6.9 & 7.3L>>Sidewinder® Turbo System
If you put a turbo on, you can get more power than that as well, because those graphs are limited in fuel to below what our pumps can provide and what the turbo lets the engine utilize )

 

Banks does not make a turbo for my ole van. That is why I have the gear vendors. Just need to finish the install.

 

I don't tow anything heavy with my truck, but the little towing I have done and the conventional wisdom I've read on IDI forums say to drop a gear, wind it out, and don't hesitate to run right up on the governor all day long. When I have a load and am cruising down the freeway, I try to not let the RPMs drop below 2K or so. Keeps me right in the sweet spot where the truck seems happiest and pulls easiest.

Mike

 

When I started driving log truck, I was told "If you can't accelerate in the gear you are in, drop a gear until you can". Was good advise then, and still use it when towing w/my truck.