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Discussion Starter · #1 ·
I've been slowly gathering parts for a 460 build that will go into a (daily driver) truck. I knew going in that gas mileage would not be good, which is fine. However I've been doing some additional research lately and some are claiming to be getting as low as 4 to 5 MPG in the city with a mild to moderately built, carbureted, non-stroker 460. That, along with rising gas prices, is kind of bumming me out.

I was building this motor to have around 550 HP/TQ. 5 speed Tremec transmission. Maybe 9.25 compression. I was wondering if anyone had some real-world 460 truck MPG numbers they could throw out there. I don't mind low MPGs; I've driven trucks my whole life, but I imagine 5 MPG city and 10 or so highway would get old pretty quick.

I was also looking at a 351W stroked to 408. I would shoot for 525-550 HP/TQ, and hopefully streetable. Same manual transmission, also carbureted, etc. In theory a 408 should get better MPG than a 460, but by how much?

I know power takes fuel, I would just rather not have to go broke feeding this beast!

I appreciate anyone's input!

-Ian, TX
 

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I can tell you that the way it is driven is the deciding factor in MPG.

I once had a 1979 Bronco with the stock 351M engine. It was a total dog. You had to have your foot 3/4 of the way down on the accelerator just to run 70 mph on the highway and it got 9 to 10 mpg. Then one day I dropped in a 550 HP 514 big block ford. If you didn't drive it like an idiot it would get 13 to 14 mpg when going down the highway. It did this with my foot barely on the accelerator pedal. The bigger horsepower and more efficient motor will get better mileage when driven easy....provided you didn't build it for all out racing to begin with.
 

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Need info on the truck. weight, mods, tire size ect.

I get 5-6 in town with EFI. 8-9 highway. Big lifted 4x4 on 40s, 6000#, c6 non-lockup converter. I drive fast.

if 2wd/manual should be much better.
 

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Discussion Starter · #6 ·
I don't have the truck yet (lol), but it will be a 70s or 80s F150 or F250. 2WD.

Probably 33 inch tires, if I lift it it won't be over 4".

I don't drive like a crackhead evading the police, but not like a grandma either.

Thanks for the replies so far!
 

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Anyone else have anything to add?
Use ten to one compression and do not go crazy on the cam profile. Use five degrees advance on the cam timing for a little bit more power at lower rpm's. It will also help greatly if you have an overdrive, also, do not go crazy on the cylinder head porting. Ports that are too large for street driving will be like attempting to blow out a candle with your mouth wide open, air speed, (or velocity) at a given rpm is very important to fuel economy.
Remember, everything in moderation, nothing in excess.
 

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Depending on what year 460 you start with you’re goals are very attainable with a lot of stock parts. Early factory head castings with some mild cleanup work, a good aftermarket intake and a properly spec’d cam will be a great combo.
 

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Depending on what year 460 you start with you’re goals are very attainable with a lot of stock parts. Early factory head castings with some mild cleanup work, a good aftermarket intake and a properly spec’d cam will be a great combo.
I would strongly recommend a set of aluminum heads. I bought a new set of them for $1200 off of the internet. There is less chance of detonation with alum. heads.
 

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Discussion Starter · #11 ·
Well I’ve got some D3 heads. Was planning on some AFRs but not sure. Never ported anything before but not out of the question. I can’t seem to find dove heads anywhere for less than the cost of aluminum heads.
 

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I would strongly recommend a set of aluminum heads. I bought a new set of them for $1200 off of the internet. There is less chance of detonation with alum. heads.
What you bought are basically a set of stock iron heads that were cast in aluminum. Lots of info on these forums show that the castings are fine it’s the components that leave a lot be desired and so it’s recommended to buy them bare and add quality components.
 

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What you bought are basically a set of stock iron heads that were cast in aluminum. Lots of info on these forums show that the castings are fine it’s the components that leave a lot be desired and so it’s recommended to buy them bare and add quality components.
I kind of figured that might be the case however it does have valves that are not magnetic. Could be monel steel or it could be stainless, I am not sure. I had decided to change all that stuff anyway, and do some porting on the areas most needed.
 
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