[serialk11r]

I mean I guess you're technically correct, make an engine that runs slightly lean, 30:1 static compression ratio with a super long stroke, Atkinson cycle cam that closes 130 degrees after BDC, tuned headers and intake for VE below 2000rpm, and you'll have super high efficiency. If you need 15hp to cruise, then such an engine would only be capable of producing maybe like 25hp peak, and you wouldn't be able to accelerate.

An engine producing more power used at peak VE would be equally efficient possibly more, but it would also be sitting there wasting fuel more of the time.

VE and efficiency are very different anyhow, VE is a function of all the breathing on the engine, header, exhaust, valves, combustion chamber/piston, rod/stroke, and most importantly cams. Peak VE is very rarely where peak efficiency is, because peak VE on mild cams tends to be achieved where the intake and exhaust resonant frequency matches the engine speed, but that number is quite arbitrary.

The higher VE=higher efficiency argument only works when the whole system is designed for peak efficiency, because usually more VE doesn't increase efficiency downstream. For example past 60% load more VE means more energy wasted on the exhaust stroke. People who think higher VE means higher thermal efficiency are just practicing wishful thinking, BSFC is way harder to figure out and measure.