[t vago]

Originally Posted by elhigh

Man, oh man. I will be following subsequent tanks on this vehicle with great interest. That's VERY impressive.

Thanks! I was rather surprised to see the results, too. 22 highway MPG on a first gen 4x4 Durango? Nobody gets that sort of mileage.

After all was said and done with regard to that picture, the tank refill saw a fuel economy of about 20.6 MPG, and the trip computer reported 20.8 MPG.

Originally Posted by elhigh

I had been wondering about looping the hydraulic lines on your stock steering rack and a steering quickener - upside-down to become a steering slowener providing extra torque - instead of all this other stuff. But shoot, keeping the power steering but getting that big an improvement is huge.

Hm... Interesting idea about the reverse-mounted steering quickener being combined with looping the hydraulic lines. I might have done that if it was just my vehicle, and I might still end up doing that on my Magnum, but I'm not sure how my wife would like that.

Originally Posted by elhigh

Makes you wonder just how lossy the stock pump is.

Back when I was still considering trying to clutch my existing power steering pump, I figured that my push mower consumed about 0.25 gallons of gasoline per hour, making 4 HP at 3500 RPM, which worked out to about 6 ft-lbf of torque at that engine speed. I then read that typical power steering pumps take anywhere from 5 to 12 ft-lbf to operate, and picked 8 ft-lbf at 2000 RPM to come up with a fuel consumption guesstimate of about 0.19 gallons per hour for my power steering pump.

Now, I can compare similar trips in the Durango, and while there are some differences, I'm going to ignore them as I think the differences would equal out. Here's why:

Both trips were pure highway mileage. Both trips have drivers who have about the same driving skills that prefer fuel economy. Both trips had the same sunny weather. Both trips covered roughly the same distance. Both trips had about the same average speed. Both trips saw extensive A/C usage. Both trips had tire pressures at 40 psig.

The first trip had 6 passengers, while the second trip only had 3, so that means that there was about 330 or so lbs not there on the second trip. That was a slight fuel economy penalty on the first trip, relative to the second trip.

The first trip was a net 200 ft drop in elevation, while the second trip was a net 200 ft rise. Probably negligible over the course of some 350+ miles of distance.

The first trip had about 30 extra highway miles due to choice of gas pump used in Indiana, and about another extra 10 miles due to running errands in-town after arriving in Iowa.

So, the first trip saw a distance of 407.2 miles covered in 7 hours 54 minutes, using 22.133 gallons, for an average speed of 51.5 MPH. The second trip saw a distance of 364.3 miles covered in 7 hours 41 minutes, using 17.709 gallons, for an average speed of 47.4 MPH. Using these numbers, I figure that the first trip saw a fuel consumption rate of about 2.8 gallons/hour, while the second trip saw a fuel consumption rate of about 2.3 gallons/hour.

Now, there are more variables which I have not covered for the sake of brevity. For instance, I never calculated average engine speed for either trip, which would have been better than average vehicle speed. This is only a ballpark estimate. That being said, the numbers tell me that the power steering pump appears to consume about 0.5 gallons of gasoline per hour, just being there. That's over twice as much as I had guesstimated, and that tells me that the existing power steering setup is really lossy.