Valiants with V8s

273 said
Mpg per unit of performance (e.t., 0-60, etc..) Eg. a NA 13s 170 vs 273 vs 440.
I bet the larger displacements might have the slight upper hand in mpg but overall be similar.

Too small an eng

273 said
Mpg per unit of performance (e.t., 0-60, etc..) Eg. a NA 13s 170 vs 273 vs 440.
I bet the larger displacements might have the slight upper hand in mpg but overall be similarengine

Too small an engine can be working hard requiring fuel enrichment and economy drops. Big blocks from the muscle car era tended to have a lot of gear which caused high cruising RPM, lik 3500. Not good for economy. With 2.75 to 3.08 gears, 20MPG on the highway was possible.
The small engines function with a bit more gear. The Mazda Miata Series 1 with the 1.6l engine all had 4.3 gears. Then the 1.8l engine brought in a 4.1 ratio, the 4.3, a 3.909 and in Europe a 3.63 gear. Different models and markets.