All else being equal - 360/440

[orangecrush]

I have either to put in my Duster. If both are built about the same with regards to bolt-ons and pistons/compression - is there a significant difference in gas mileage (thinking about if/when gas goes back up).

 

[rumblefish360]

LOL, OK, if there stock.....

I did get 20 mpg's out of my 360 in my '79 Dodge Magnum. (3800 lbs.)

It was stock except the following;

340 air cleaner. trap door model.
625 emisions AFB Carter model.
MSD 6 box and coil.
Viscous fan.
Dual exhaust of the exhaust manifolds @ 2-1/4, H piped and twin cats.
(Legal purposes)

904 tranny and 2.76 gears with 235/60/15's.

There was more mileage in it, never got to finish tinkering with it. Headers would have helped and of course, no cats would have helped. A mileage cam could have been installed. A nice split duration cam would have been helpful in mileage and power.

Once you start bolting on parts for power, the 360 will have to work harder since it's cubicly challanged to make the same power as the 440, so gas mileage becomes a wash.

 

[moper]

Yes. The 440 takes about 23% more fuel than an identically built 360. Regardless of build up, the engine is 20% larger, and 15% heavier.

 

[orangecrush]

What I needed to know - thanks. Just thinking about those cruises or shows that are 100 miles round trip or so - if we see 4.50 again, it'd make a difference at the pump - still plan on healthy build with either but mpg adds up quick at those prices. If I thought we were going to stay at >2.00 for premium, that'd be another story.

 

[rumblefish360]

gas prices aside, ethier engine can be made to sound good and still get a decent amount of mileage. Though an overdrive will help among other things like lock up converter or a very efficient converter for the regular tranny, tall tires and gear ratio will help.

A nice sound also comes from a tight centerlined cam and a quick lifter rise. Headers will amp up the sound through the tone & volume setters, the muffers.
2-1/2 pipe is a good speaker size for this.

 

[MopaR&D]

That would be interesting to see someone do a similar build to the high-compression 360 Magnum applied to a big block with an eye on gas mileage. Fast-ramp cam, well-flowing closed-chamber heads, flat-top pistons, etc.