If larger injectors are installed—that is, injectors with a greater flow rate—an engine tuning shop is usually required to re-tune the map—the fuel curve—to achieve the correct air-fuel ratio. To acquire a safer tune in a supercharged engine, where cylinder heat increases with boost, tuning shops will often adjust the air-fuel ratio to 12.0:1 at full throttle as opposed to around 12.8:1 on a naturally aspirated engine. In cruising conditions, air-fuel ratios will remain at 14.7:1. Read More.