Quote: And just to be clear, when I say I think a boosted engine can be more fuel efficient than the same engine NA I'm talking single digit % increase.
With your version explained you're "cheating" by not having the same tailpipe air/fuel ratio.
It would only potentially make a difference at higher loads, it would definitely not be true from an overall perspective. You could run a speed/load map of an n/a engine and the same engine with a turbo added, and there may be a small number of points where the turbo engine is more efficient because it could make a higher torque value at a given engine speed, but it would most likely be at higher loads, if any at all. Adding the turbo alone is going to decrease fuel economy, between the weight added to the vehicle and the increased pumping losses with the turbo in the exhaust stream.
I would not be adding a turbo to a motor thinking fuel economy would improve. Fun factor, yes. Fuel consumption, no.
'18 Ford Raptor, random motorcycles, 1968 Plymouth Fury III - 11.37 @ 118
