sb difference fuel consumption

Generally speaking less cubes = more MPGs.

But other things play into this......

Often peoples driving stile changes as power goes down....

For example you may have a tendency to push a 318 harder than a 340..... Resulting in the 318 getting worse MPGs simply because driving style.

So part of this is mindset..... Do you have the mindset that will allow good MPGs?

You really need to decide what you will be happy with... Pick a 1/4 ET for example...


If you build a 318 that gets 25 MPGs but only runs 16.5 1/4 mile times would you be happy?

If not you will have your foot in it all the time trying to make up for the missing power and bleeding off its MPG ability....

Really.... It's impossible to answer your question without more info.

Give us some numbers.... Yet another example...........

Guys.... I'm doing a 65 dart 4 speed build (rear gears are... ). What would be my best choice/build of small block if I'm looking for at least mid 14s in the 1/4 while returning at least low 20 MPGs on the highway........