Updated: Dec 11, 2022
Anti-lag and two-step are two commonly confused systems. They have a similar mechanism and work in a similar way, but they are different in function.
Two-step is a secondary rev-limiter that increases turbo boost pressure at a standstill and allows for the best possible launch, while anti-lag maintains turbo boost pressure while off the throttle, such as during a gear shift, reducing turbo lag.
In this article, I will explain how two-step and anti-lag systems differ.
Table of Contents:
What Is Anti-Lag?
The anti-lag system (ALS) is a technology and method intended to minimise turbo lag on turbocharged engines, reducing time to boost, improving throttle response, and improving performance in tuner and racing cars.
Anti-lag is a technology intended to minimise the delay between throttle input and turbo boost pressure, often known as turbo lag.
Turbo lag is caused by a variety of factors, including the following; a larger turbocharger, charge pipework with a large diameter, or exhaust pipework with large diameters.
There are other causes for turbo lag, but that is the majority of causes.
Below is a video explaining more about anti-lag.
Some anti-lag systems may provide turbo boost pressure even at low rpms, when the turbo would normally be unable to spool.
Most anti-lag systems alter the ignition or fuel timing/injection volume, causing excess fuel to leave the combustion chamber to then combust in the exhaust, causing popping and banging, and sometimes flames to exit from the exhaust.
This is the process that helps create pressure in the turbine of the turbocharger, increasing boost pressure while the throttle is lifted, during a gear change, or while launching, etc.
There are a multitude of anti-lag systems, as shown in this article. Most of these systems work in a similar way, though.
What Is Two-Step?
Two step is sometimes called 2-step. It is essentially a secondary rev limiter that can work in a similar way to anti-lag and provides similar results.
At a particular RPM, ignition or fuel is stopped when a specific speed is reached, a switch is switched on, or a combination of the two. This keeps the engine running at the specified RPM, which is ideally the optimum RPM for launching the vehicle.
An ignition cut is used by the majority of aftermarket systems. Two-step systems are sometimes used by manufacturers as part of launch control systems.
Fuel cuts are often used by manufacturers because they maintain the engine running at a constant RPM without any popping or banging.
Manufacturers also have a tendency to just design it such that the ECU maintains an RPM when launch control is enabled.
Two-step is an extra rev-limiter that aids in the development of turbo boost pressure and is often employed as a form of launch control.
What’s the Difference Between Them?
Anti-lag is a technology that keeps a turbocharger spooled and maintains or increases boost pressures while you let off of the throttle, change gears, etc.
Using anti-lag reduces latency between throttle input, turbo boost pressure, and therefore acceleration. Only turbocharged engines can utilise an anti-lag system.
Two-step is a supplementary rev-limiter that maintains a constant RPM, providing boost pressure which provides the greatest possible launch.
A two-step launch control system may be accomplished via the use of an ignition cut, a fuel cut, or a similar process.
Sometimes, naturally aspirated and supercharged vehicles may use a form of two-step.
You can also have both anti-lag and two-step on the same vehicle as they have different purposes, usually they will both result in popping and banging from the exhaust.
Although many people confuse the terms, anti-lag and a two-step are not the same thing; nevertheless, they do function in a similar manner.