[Naja]

Ed -
I have a little older diesel than yours - '96 F-350. It was listed as having 215 hp (on the valve cover). I haul my Cobra in a 32 ft., enclosed gooseneck (40 ft. overall) from Houston to CA to UT (over the Rockies), etc. I am running at Ford's rated maximum combined capacity of 20,000 lbs.

I'm more interested in getting a little better gas mileage than saving an hour on my trip, so I don't go 70-80 mph - more like 60-65 (yah, I'm that da*%# slow guy).

I got a '50-60 hp' (mild increase) programmable chip (I think Superchip) put in my engine about a year ago. Before, with an empty truck (no trailer), I could get 20-21 mpg on the highway, and about 17 around town. With the loaded trailer, I got 11-16 mpg, mainly depending upon steep hills and headwinds. I didn't think that the towing performance was too bad, but a good headwind really knocked it out of me (steep grades not as bad).

After the chip, I noticed a significant difference in acceleration capability, pulling up hills, and a little difference into the wind (I have a 6.5 ft. high trailer - interior - so I have less frontal wind resistance than most trailers). I haven't hit strong headwinds, yet, but I get 13-17+ mpg with the trailer, and about the same as before without the trailer. I haven't had the 'truck only' out for a long highway drive, so I don't know if I can get over 20 mpg, but I suspect it would be better.

Problem is: If you use the increased hp, you use more fuel. The question is: Does that increase in power allow you to use less fuel to cover the same distance? I notice that I don't have to put the accelerator as far down. That should translate to better fuel economy.

Hope this helps.

Regards,
Frank Newman