This is for car people, what’s the difference between Antilag and 2-Step?

1.03K views

This is for car people, what’s the difference between Antilag and 2-Step?

In: Engineering

Anonymous 0 Comments

Anti lag and 2-step rev limiting are have fundamentally different purposes on a vehicle (although sometimes have similar implementations).

Anti-lag is intended to keep the turbo spooling while engine power is low; whereas 2-step rev limiting is used to give a more efficient launch by reducing engine power to minimise wheelspin.

Anti-lag essentially works by making sure there is fuel and air available to burn in the exhaust manifold, which increases the temperature and pressure of the exhaust which keeps the turbo spooling.

There are different ways to achieve this, the most common is delaying the ignition timing so that the fuel-air mixture doesn’t have enough time to burn fully before it is exhausted. It can also use fuel injectors/throttle bypasses to achieve the same effect.

2-step rev limiters are simply a second rev limiter at a lower limit than the normal redline limit, to limit how much power goes to the wheels at launch to decrease the chance of wheelspin.

Rev limiters can work in lots of different ways. OEM limiters generally just lean out/switch off fuel injection to decrease the engine speed (usually switching the fuel on-off-on-off etc quickly while at the limit, which gives it the characteristic sound). Aftermarket limiters can do more complex things such as delaying ignition timing to burn less fuel and reduce engine speed (similar process to anti-lag but used in a different situation to achieve different results).