I had a 351 in a 90 F250, and I got marginal improvements from a dual exhaust sytem. I would spend the money on that though, unless your existing system was shot. Other than that, I didn't find any mileage hiding anywhere. Tried an aftermarked msd ignition, fancy filters, nothing really helped. All the power of a 302 and the fuel consumption of a 460 was my consensus. Maybe someone out there has had better luck?

 

Yeah the 351 to me is the most pointless motor ever made just like the 360. No power and sucks gas like crazy. I think it only has like 10-15 more HP than the 302, and I'm sure its got a bit more torque too. Oh well, I guess its nothing like the straight 6 where it gets 15, then you give it a tune up and you get 23.

 

We have 2 351W you out lucky.

1 is Former 95 F250 with 60K miles plus 10K miles on new 351W. It was plow truck. Bought it was 9 mpg. Fix exhaust leak and change axle gear from 4.10 to 3.55. We got 14 mpg city but mostly 15 city/hwy


1 is 96 E350 passenger van 15 seats. 72K miles. City 11-12 mpg and highway 13 if you make LONG HWY trip then 16.

 

So I guess 12- 13 mpg is all I'm gonna see in the city then. Mine has an exhaust leak and the pos E4OD trans has issues shifting into overdrive so it revs up sometimes now.

 

Exhaust leak is BAD when I fix that my mpg from 9 went to 10 to 11 but most it 10.

Keep OVERDRIVE OFF until you around 50 mph. They lug engine. You should install vacuum gauge on it to tell how heavy you on gas.


tires I would put max psi what it say on sidewall. I bet it 45 or 50 psi for D load on F150.

 

First things first, maby yours is not running right, my 351 in my bronco halls freakin ass. And would get 14 or so drivn normall. Dual exhaust is a waste, go with a single 3inch exhaust and a nice drop in filter. Go to fullsizebronco and search 6litre tune up. Huge improvements, run motorcraft plugs never bosch. Change the fuel filter. The torque of the 351 is where its superior to a 302 had a few of both. I like 302s no doubt but they lack the torque of a 5.8 also what gears do you have? Honestly if its lower than a 3.55 that may be why mileage is shit unless you do alot of freeway. My 92 bronco had 3.08s and sucked in the city, i got beat by city buses.

 

run motorcraft plugs never bosch.

Is this proven? I always run Bosch pure platinums with a tuneup and it always got better mileage. My 302's loved em got 19 with my towncar and 22-23 with my cougar both times it was 3 mpg better. Along with fuel filter,air filter and wires/cap/rotor. My bronco only never liked those spitfires.

 

I highly disagree with max psi, honestly it doesnt help that much to offset longer brake distance. Great you get more mileage but its rainin and a kid runs in the street infront of you and you hit him, cool ur gettn better mileage right.

 

I have a crewcab 95 F350 4x4....gets about 15mpg's city

Basically stock with auto overdrive trans and 4.10's , but it's on 37's :thumb:
Has exhaust leak, recent cheap ass autozone tune up .....includeing fuel filter ...guess some people have all the luck ...:naughty:

 

I would say 12-13 mog is not bad.

lol...my built 351w in my old ford only got about 4-6 mpg.

 

I've been discussing this matter alot recently with my friends. I just did a tune up (fuel filter not included), and with the free flowing exhaust(2.5 inch, flowmaster 40 series, no cats), drop in K&N filter, emissions bypassed and eliminated, and 32-11.50-15's, i get about 9 in town, and 13ish on the highway in my '93 351 FSB. the mileage goes up when i take the top off (weight reduction i assume), but mostly just in town. I've never heard of anyone getting better than 17 in a 351 windsor powered truck, no matter what body style.

 

i run autolite plugs in the Brownco.

 

Whoever said its probably not running right your right, it misses when I get on the gas and you can tell its way past due for a tune up, yet if I drive like a grandpa I get about 13mpg. Gonna do a tune up most likely next week and get back to everyone. I don't know what gears it has but it still hauls ass even with a miss fire. I raced a small 318 dakota last weekend and left him in the dust. I was actually surprised it did that well for a full size truck. Never been a big fan of the 351.

 

My 351 rips and its stock, well considering what it is. My Bronco on 35's is just as fast as my buddies 06 Grand Prix up to 96 mph that is. I can get 15+ mpg on the highway if I do 65, be glad you dont have the 302.

 

I tried the Bosch Platinums in my car and after awhile it developed a miss, come to find out 2 of the electrodes were toasted off. Switched to motorcraft fine wires and have had zero issues in 2 years, not saying they're junk plugs but I prefer the Motorcrafts and Autolites.

 

Double check the timing.

 

I have a 302 and a 351. the 302 only gets about 15 mpg in city and the 351 gets about 12. they have about the same mpg but the 351 makes about 20 more hp but over an extra 100 pounds of torque. Nether of them can get many more mpg. But with a bronco or an f150 12 to 15 is pretty good. they are both bigger vehicles and are built for power not gas mileage.