318 or 360

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dave ellis said:
All else being equal, how does the mileage of a 318 compared to a 360?
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Equally in a truck pulling the same weight trailor, the 360 will get better MPG. In a Duster in 2bbl form, the 318 will get better MPG. Right now, I cannot tell any noticeable difference between my 360 Duster and my 318 Duster for MPG. I've not checked neither
 
Probably the 360 will consume more fuel. But compared to the 318 may not be all that considerable. 318 to a 440 that will be more noticeable for sure.
 
Own a dart sport that had a Slant 6. It sipped fuel but was very anemic power wise. Now has a hot 360 and fuel mpg is nowhere near the 6. But the power now makes up for mpg's!
 
in a mates 70 coronet we swapped a stock 318 (bar headers and v/s 600 4 barrel) for a 'built' 360 (with same headers and a 750 v/s) and mileage went from 25 ish to 15 ish (10 ish towing a caravan), no other changes. performance was vastly improved mind.......
 
Really impossible to say. Lots of factors to consider such as gearing, where each engine's sweet spot is, efficiency of the ports & intake. Etc.
 
The smaller engine can get great mileage IF it is in a light car. If the 318 is in a heavy truck with big tires, it will be overworked and not get much better mileage than a 360 that isn't working as hard to move the mass.
The longer stroke of the 360 generally means that it will have a lower torque peak, all else being equal to a 318. Less throttle opening to do the same job, though that narrow throttle opening is feeding 42 more cubes...
 
I completely am outta line here, but supposedly the 3.7 gets 2-3 mpg less than a 4.7. The 4.7 has way more juice, that being said , the 3.7 ain't bad on 275 or I-4, but swills fuel like a wino on the street...
 
ALL else equal, the 318 will knock down better mileage. 360s are hawgs.
 
dave ellis said:
All else being equal, how does the mileage of a 318 compared to a 360?
Click to expand...
All things being equal?
As in slide the 318 heads and cam onto the 360? Or
Slide the 318 under the 360 heads?
I mean just what does all things being equal mean.
The 360 cam is about two sizes bigger, so you better be more specific. The 360 heads have bigger ports and will be sluggish on the 318, plus the port mismatch is gonna be a lil issue.
Either engine can be tuned to the same steady state fuel consumption, all other things as to the cars, being equal. But getting up to speed, and how you get there, will make some difference.

But here's the fly in the ointment; The 360 is 13% bigger and has a lot more torque. You can easily take that 13% gear reduction away from the 360, and cruise at 13% less rpm, and then the 360 has a solid potential to use less fuel in steady-state than the 318, yet have about the same low-rpm performance. That is a win/win situation.
13% is a lot. That's ~2.76 compared to 3.23s
13% difference at 65Mph is about 340 rpm.
Furthermore;
You could install the 318 cam, into the 360 and pick up about 8 to 10psi cylinder pressure ............... Giving you the potential for even better fuel mileage and low-rpm power, at the expense of hi-rpm power.
 
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