six barrel
What’s the fuel economy goal your trying to achieve? You must have a number considering you’ve already measured an actual 18mpg. You looking for 19 or 35mpg?
Keep in mind a lightweight Feather Duster/Dart Lite got over 30mpg but that was with a heavily tuned for fuel economy slant 6.
I wonder if salesmen at Ferrari/Bugatti/Lamborghi/Land Rover and other fuel thirsty vehicle brands hear clients complaining about how their vehicle has hefty fuel bills.