Gas Mileage

[Brando32]

I know that broncos are really a good investment for saving on gas, but i want the best gas mialge io can find. SO what has everyone else got for gas with their 351m or 400... stock, modified, whatever... because if headers, exhaust, camming, and intake and carbs actaully help i might go that direction, or i have been thinking o swapping in a straight 6 and than getting the intake and carb for that. Probably about the same for horsepower and torque and the straight 6 might do better gas mileage... Any suggestions?

 

[Rons beast]

I think you ment to say that Broncos are NOT a good investment for gas mileage. These trucks are around 7000 Lbs. There is no way to get good gas milage out of a vehicle that is that heavy. Swapping in a six will probably not save much. The lack of cubic inches will make the motor work more to get the vehicle moving. Cams, headers, carbs...etc. will add some power, but the power comes from burning the fuel, ( albeit more efficient).

I feel I'm doing pretty good getting about 15mpg, on average. I have a stock 96 5.0, that is kept in good tune.

Good Luck

 

[Brando32]

Yeah, i forogt to put the "not" for a investment. Yeah i know vehicles of those years weren't really made for saving no gas, but it would just be nice to figure out something that will make it move without issues, and get decent mileage.

 

[Krafty]

Ron one point is that if you compare a 351W to a 351M or 400m, there is a noticeable difference in fuel mileage. I believe this is because of different bore/ stroke that achieves the same displacement.

If you are set on a swap because of mechanical issues then I would find a late model efi 302 or 300 engine and trans combo and swap away. if you stick with the carb your mileage will suffer and you will loose about 30 to 40 hp depending on which engine you pick.

the 300 302 and 351W ( and I think C) use the same small block bellhousing bolt pattern, the 351M 400M 370 429 460 and 512 have the same big block bellhousing bolt pattern. so if you drop to a smallblock then you'll have to change transmissions

oh and ron you're stock late model efi 302 has about 60 more Hp than a 1978 351M and much better mileage

 

[Brando32]

If i was doing a swap, i would swap in the 300 and 4-speed tranny from a 77, so it would all pretty much be a easy swap since they're the same space in the hood compartment... I just donm't want to throw too much money into the 400 and than want a 300 still... because i am a loud kind of person, but i want soem better gas milage the 400 can't offer...

 

[Bully Bob]

IMHO,

Invest in a used Toyota, etc. as a daily driver. >-

If swapping engines gives 2-3 MPG gain (or changes nothing) it will take 5-10 yrs. to make up the diff. (expense of the eng. & swap) $-)

A "puddle-jumper" 4 banger will tripple your mileage & make up for the (purchase) exp. in a couple yrs.

Also., saves wear & tear on your rig.