I get around 16 at 60 mph with 7.3 e40d and 4.10s.

 

I now have a fuel mileage update.
I used different driving styles and the results are interesting.

When I first got it, I got-----

13 mpg city driving, taking off fast like everybody else.
18 mpg on the freeway @ 70 to 75 mph.


After a $10 modification.

13 mpg city driving and no change.
20 mpg on the freeway @ 70 to 75 mph after I blocked the radiator grill off with a sheet of aluminum.


Then I changed my driving style.

17 mpg city driving, taking off slower than everybody else.
22 mpg on the freeway @ 60 to 65 mph.


Then I changed my driving style again.


19 mpg city driving, taking off a hell of a lot slower than everybody else seriously pissing them off, and turning the engine off at red lights.
24 mpg on the freeway @ 50 to 55 mph.


So I now can get 19 city mpg and 24 freeway mpg and have yet to install my SMACK Hydroxy booster.

 

I can see why there would be an increase by doing 55. These trucks run very easy at that speed. What does the sheet of aluminum in front of the radiator do?

 

It helps direct the air flow around the truck.

The open grill, mirrors and uncovered pick up bed all act like parachutes and either slow you down, or you could say, make your mileage down on the freeway.

The mirrors will come off when I can get a set of three cheap cameras and monitors, so building the sloping bed shell/cover is the next project after the Hydroxy booster (that I already built) is installed.

BTW I drove all summer on the hottest days and the engine never got above normal operating temps and helps things warm up a little faster in the winter

 

OK archangel, When can we see some pics of that grill mod you keep going on about.

I have some light aluminum sheet metal and I might want to try this. I can average 20 MPG at 70 MPH empty, but anything I can do to improve on that is fair game.

Now that I have finally killed off all of the fluid leaks, a belly pan may also be in the works for me eventually.

 

Blocking off the radiator helps maintain an even engine temp.
Remember with engine heat supplying the means for combustion, higher temps mean better fuel combustion.

Downside, the coolant going into the oil cooler will be warmer and big loads on warm days will require you remove the radiator obstruction.

If you want to try this, I would have a real temp gauge installed and keep a close eye on it until you know how it will react to the reduced airflow.

With the heat a turbo engine can produce, they might not be very happy on a warm day.

 

That isn't true at all about open beds (WITH tailgates).

Mythbusters BUSTED this myth on their show not long ago.

The open bed causes a high pressure area where the air flow is deflected off of and never DIRECTLY hits the tailgate.

 

Exactly. That's why you see all the big rigs covering their grills in the winter time.

 

The Mythbuster thing was on if a truck with the tailgate up or down gets better MPG.

The tailgate up was better.

The amount of air reversing directions to flow into the bed and where it was coming from is the reason for that.

However, if you had a bed cover that was as high as the cab in the front, closed sides and only as high as the tailgate in the rear, the reduced drag would increase MPG even farther.

Back in the 70's gas shortages Overdrive Magazine did tons of research on big rig drag.
The hole between the cab and trailer and the hole behind the trailer suck up more HP than it takes to shove the frontal area through the air.

Something as simple as a bug deflector on the front of a conventional tractor could suck up as much as 25 HP, because of the air bubble it created on the hood in front of the windshield.

I wish I still had that article, it was informative as far as drag, HP and MPG go.

 

I've seen race trucks with rear covers that slope from the cab down to the tailgate. I guess for air flow. As for the rad cover I'm surprised the truck doesn't overheat in the summer or cause the fan to run constantly and use more fuel. I'd like to know how that works out long term.

 

Archangel,
For the rear view mirrors, maybe you could attach something to the front side of the mirrors to cut through the air more easily.

 

I have a 1994 F 350 4 dr 4x4 an I get 12 to 14 mpg an I start mine on the frist time after my wait to start goes out I let it run for about 5 min when it is really cold then I drive off .