joegeoghegan317 never mentioned what vehicle he was talking about. My presumption was that he is talking about an F series truck. Nearly twice the weight of that little Falcon body Ranchero. His target milage was 20mpg. If he implemented all the items I suggested I think he could go 24mpg.

 

With our record freezing weather here in Dallas last week I was forced to slow down. 2 days to work and back and all the running around town I have to do for work I got 17.9 in my 05 SD 6.0 in city driving Thats up 4 to 4.5 mpg. And it was do to slowing down.

 

Interesting thread!

I have a 390 in my '70 F100. It is built up as follows:

TRW L2291 pistons, .030" oversize
Ported and polished C7AE-A heads
9.7:1 compression
Crane 343941 cam, 272/284 degree dual pattern, adjustable valvetrain
Edelbrock Peformer RPM intake
Headers, 2.25" dual exhaust
Mallory Unilite distributor
Holley Commander 950 TBI electronic fuel injection system, see here for exact system:
http://www.holley.com/products.asp?product=950-22S
C6 transmission with shift kit, and 3.50 gears in the differential.

Desktop Dyno says this thing makes 412hp @ 5500rpm, and 443ft-lbs @ 4500rpm. The butt-o-meter agrees.

On trips, it gets 17mpg if I drive around 55 to 60 mph. 60 to 65 gets about 15mpg. Running it around town with my foot into it all the time, it gets around 10 to 12mpg. If I really keep my foot out of it around town, then maybe 14mpg. But that's hard to do. My lead foot usually takes over. That power is addicting.

I think 20mpg is realistic with an MPFI system on a properly built 390 in an F100.

 

Wow Rusty, you dropped a few bucks on that rig but it sounds fantastic!

Can you burn regular gas with the 9.7 to one compression?

 

rusty, was that mileage with a bed cover, tailgate up or down? that could add to the numbers.

 

Rusty, that sounds like a great setup. I would like to try it in my truck.

 

hey bdox 9.7 is easy on pump gas. i had a fairlane with 10.5 that ran good on pump gas.

 

Tailgate up, no cap, cover, or anything.

I have been burning 89 octane gasoline. In Iowa, it's cheaper than the 87, and as such I haven't tried the 87 yet. The motor is very sensitive to timing. You have to get the timing curve just right for best power and mileage without pinging. The fuel injection system I mentioned does have an O2 sensor, and I'm sure that contributes to mileage in a big way. These FE's, when built correctly, are NOT prone to pinging.

The problem is, that at 55mph, everyone always tailgates so I end up having to go 65 anyway. And away goes the mileage.

The motor is nice, but the rest of the truck is falling apart around it. I took a lot of it apart this fall, looking to do a semi-restoration on it, patching holes in the floorboard and fixing some electrical issues. Well, the snow came early this year and now it's parked out back in the snow.

 

[QUOTE=rusty70f100]Tailgate up, no cap, cover, or anything.

I've heard that the tailgate being UP is better than being down. Somehow I just can't believe this theory.

DD

 

[QUOTE=71_4x4_390]I'm with you, it seems counter-intuitive, but Car and Driver magazine did some tests a few years ago, using very sensitive instrumentation. Their conclusion was that tailgate up provided less drag. There is more turbulance behind the cab with the gate down.

 

As you all can tell by the name, I know nothing about the ford anything!

I am a previous '66 Jep CJ owner in which I restoed with some buddies when I was 16.
But, I moved onto greener grass with a '78 Ford F-150 Ranger. Seems to be a pretty good buy. The only thing is, I want more then 160 H.P. and a little better gas mileage out of the truck.

Is there a better engine for me to utilize then the 351 M?

 

...Welcome Thenewguy,,to Ford Truck Enthusiasts!

We are happy you have chosen the best source for Fords!

Enjoy FTE....and
JOIN CLUB FTE -SUPPORT THE FORUMS!
…..See you on the boards.

 

The TV program Mythbusters (on Discovery Channel) has tested the tailgate up or down question as well.

Tailgate up is more aerodynamic. It turns out that with the tailgate up, there is a 'pillow' of air in the bed that allows that air to flow cleanly over the back of the truck.

They tested it with two identical Ford trucks. The truck with the tailgate up went about 30 or 40 miles further on a tank of gas.

They also demonstrated the airflow in a water tank where you could actually see how the air flowed over the truck.

They have also tested the "AC on" vs "windows down" myth. Turns out that its more fuel efficient to drive with the "windows down and AC off" up to about 40 or 45 MPH. Above that, windows up / AC on is better.

I consistently get 13 to 14 mpg in my 72 Crew (390 2V, C6, 3.54) on the freeway (at 65 mph).

I believe 20 is very doable.

 

get a vacuum gauge, and try to keep the needle as high as you can while cruising, because a lot of people get up to speed and keep their foot in it, but if you let off just enough to cut most of the fuel yet cruise at a constant speed, you can get decent mileage...

I had a 67 with a 302/auto and got 12mpg mostly, but when I drove gentle and paid attention to the vacuum gauge, well, a trip from OH to IN, fully loaded with everything I owned, with a flapping tarp over my bed, netted me 16mpg. It can be done if you're careful.

 

20 MPG is not out of reach with a 390 in a 2wd truck. My 7500 pound 1970 f250 4x4 with 7 inches of lift 35x12.50 tires dana 60 front axle and 600 pound 1/2" plate winch bumper holding a 10 ton garwood pto winch with 75 feet of 1/2" cable would not seam to a candidate for anything over 8 MPG. The truck gets an easy 16-17 MPG highway at 65 mph, drops to 12 in the city and about 10-12 with any trailer under 22K behind it on the freeway. When the truck gets over 30,000 GVW the mileage drops pretty drastically. Can't manage much over 8 mpg with a huge load, but I don't have a CDL or T-plates on the truck so I probably shouldn't haul over 26K GVW anyway.

The motor is a very mild 390 901 cam, 9.8:1 compression, C8AE truck heads with stainless valves, 428 CJ iron intake, HV oil pump, Dove rockers. Hyper pistons, balanced and blueprinted to dead nuts. Probably an easy 350 horse @ 4300 and 475++ lb/ft from 2200 to 3500 rpm. Tranny is an NV4500 5 speed and the gears are 4.10's. The O/D tranny was only goor for about 2 MPG. The best mileage upgrade I did was a brand new flexalite clutch fan. The fan alone was worth 3 MPG. I run 10W30 castrol GTX.

My gas mileage getter is a 1970 F100 2wd with a 300 six and international close ratio T-19 4 speed. 3.50 geared posi 9 inch. The truck is totally stock with original 16" super skinny wheels and 29X4.50X16 E rated radials. The engine is a 4.9L fuel injected six from a 1989 E150 van with roughly 200,000 miles on it and still running like the super champ it is. I used the stock van EEC, but eliminated the EGR, air injection and other emissions junk and TIG welded a custom downpipe off the factory headers into a single 2.5" pipe and turbo muffler. I'm not a six banger fan, but you definately do not know you're driving a six when you drive the truck. It's a fun 200+ horsepower and loads of torque. Moves the 4000 lb truck around great. The truck gets 22 city and 28 highway at 70 to 75 MPH. The worst mileage ever was 17 mpg that I got doing 85 mph over snoqualmie pass (20 miles straight up). I ran the 1970 carb and intake on the 4.9L for a few months and still got 23-25 mpg freeway. I've got less than a grand in the truck including the purchase price ($400 in all new front suspension) and it's dirt cheap to drive, looks decent and works perfect. The best part is how cheap 300 six parts are at the parts store. waterpump-$14, clutch-$70, starter-$32.

Dustin