Our VIP Package gets you every single course at 80% off the individual price. For a limited time, save an additional $100 with coupon code 100VIP. Learn more

Understanding AFR: What is AFR?

Watch This Course

$89 USD

-OR-
Or 8 weekly payments of only $11.13 Instant access. Easy checkout. No fees. Learn more
Course Access for Life
60 day money back guarantee

What is AFR?

01.10

00:00 Air fuel ratio or AFR is the way we as tuners most often refer to the fuel mixture the engine is running at.
00:08 As it’s name implies, AFR describes the ratio of air to fuel.
00:13 This is one of the primary indicators we are watching and adjusting when we tune an engine.
00:18 Since the airflow through the engine is a function of engine capacity, RPM, and volumetric efficiency, with the exception of aspects like continuously variable cam control, we can’t influence the airflow from the laptop key board.
00:33 We can however adjust the fuel delivery and this is how we can adjust the mixture the engine is running at.
00:40 One important aspect to understand here is that when we talk about AFR, what we are interested in is air mass, not volume.
00:49 This is because air fuel ratio describes the ratio between molecules of oxygen and molecules of fuel.
00:56 Mass can be effected by both temperature and pressure.