With something hot rodded or even old school factory performance cam etc, the AFR load illustration from Larew provides a pretty good idea. I've reposted it here (FABO) but you can
also look at some of the other graphics Tuner posted (one is from Chrysler) here. https://www.tapatalk.com/groups/racingfuelsystems/viewtopic.php?p=16323#p16323