Gas mileage 460 vs 351m

Rico · Sep 28, 2010

I have a 1979 F-150 4x4 and I wanted to make up my mind on swapping in a 460 or keeping the good ole 351m in it. But my question is why do these two engines with about 109 cubic inches apart have the same gas mileage? This is really stumping me. :icon_confused:

If any of you guys can help me confirm this I think I'm gonna go with a 460 in my truck especially since I plan on bigger tires and off-roading a lot with it.

adsm08 · Sep 28, 2010

More available power means that the engine has to do a lower % of its maximum work to do the same job. Less work means less fuel.

The 351M is kinda nerfed by emissions crap and a less than wonderful design. It has a long stroke and low compression (for emissions) which means it needs more fuel to give the same power. The 460 doesn't have that issue.

GoodOld85BlueBalls · Sep 28, 2010

You want a 460 and your worring about fuel mileage???
:icon_rofl:

Just shoehorn it in, this I gotta see in a Ranger!!!!
Im thinking..........BUILD THREAD!!

Rico · Sep 28, 2010

I'm thinking about the power advantage not the gas mileage crazy. :annoyed:

If the gas milage is the same then why not go for the bigger motor?

country0001 · Sep 28, 2010

should be bout the same

02RangerXLT · Sep 28, 2010

460 and gas mileage shouldn't be in the same sentence... our F250 probably got 8mpg empty... 5 or 6mpg pulling a trailer... yeah, I don't care what you put it in, the 460 is a gas hog.

The purple one · Sep 28, 2010

I had a 1978 F150 4X4 super cab with the granny 4 speed way back when. It had the 351 M and I could get 15 MPG on a very good day empty. That truck would pull down a house too.

adsm08 · Sep 28, 2010

The purple one said:
I had a 1978 F150 4X4 super cab with the granny 4 speed way back when. It had the 351 M and I could get 15 MPG on a very good day empty. That truck would pull down a house too.

The 351M isn't a bad engine, but it doesn't hold a candle to the Cleveland, the Windsor, or the 460

COPPERHEAD85 · Sep 28, 2010

460 with a after market timing chain and gears.
Parts are pretty cheap believe it or not,in the process of building one myself,still in the collecting parts and research phase.

2.9XLT · Sep 28, 2010

460 definitely, it'll get the same gas mileage as a 351m, and make more power. Plus performance parts are a lot easier to find.

feellnfroggy · Sep 28, 2010

Same as the expeditions with the 5.4l and the 4.6l the 5.4 gets better mileage. Just like running too high of a gear, 5th when 3rd will do. Your dumping a bunch of extra fuel to get the work done, and its being wasted. but seriously your talking about a 351m (which is basically a small block 400) and a 460. Why the hell has gas mileage even crossed your mind? Think of shuttle launching into space when you think gas mileage.

adsm08 · Sep 28, 2010

COPPERHEAD85 said:
460 with a after market timing chain and gears.
Parts are pretty cheap believe it or not,in the process of building one myself,still in the collecting parts and research phase.

Talk to 7.5_STX. He's managed to cram a 460 into his 91.

Boggin · Sep 28, 2010

if i were you id keep the 351M. it will be just as good on gas or better, and unless your looking for a shit load of hp your wasting your time and effort. alot of people bash the 351m but i love mine and would not trade it for a 460 for the world

adsm08 said:
The 351M isn't a bad engine, but it doesn't hold a candle to the Cleveland, the Windsor, or the 460

your kidding right? my 351m will tear up a 351w like a freakin 2.9 lol

Boggin · Sep 28, 2010

adsm08 said:
Talk to 7.5_STX. He's managed to cram a 460 into his 91.

i have a buddy who is currently cramming a built 429 in his 2nd gen, hes t120r on here but i dont think he posted yet

85_Ranger4x4 · Sep 28, 2010

2.9XLT said:
460 definitely, it'll get the same gas mileage as a 351m, and make more power. Plus performance parts are a lot easier to find.

Dunno about that, stroker kits are pretty common for a 351M... all you need is a crank and pistons out of a 400. That is a heck of an engine.

feellnfroggy said:
Same as the expeditions with the 5.4l and the 4.6l the 5.4 gets better mileage. Just like running too high of a gear, 5th when 3rd will do. Your dumping a bunch of extra fuel to get the work done, and its being wasted. but seriously your talking about a 351m (which is basically a small block 400) and a 460. Why the hell has gas mileage even crossed your mind? Think of shuttle launching into space when you think gas mileage.

Same with the 4.2, 4.6, and 5.4 in the F-150, they all get about the same :icon_confused:

Even a 302 in a fullsize doesn't get much better milage than a 460, mid teens vs low teens.

Gas mileage 460 vs 351m

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