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Rolling Anti-Lag: What It Is & How It Works (Explained)

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Last Updated on: 7th September 2023, 12:47 am

Rolling anti-lag is a system used to reduce a phenomenon known as of turbo lag.

In an effort to increase power output of engines and improve efficiency, turbochargers are used. However, turbocharged engines have a drawback of “turbo lag”.

But what is rolling anti-lag, how does it work and why is it used?

What Are Turbochargers

Turbochargers are a type of forced induction system that increases an internal combustion engine’s efficiency and power output by forcing extra compressed air into the combustion chamber.

A turbo allows smaller engines to produce much more power than their naturally aspirated counterparts.

a diagram of how a turbocharger system works

What Is Turbo Lag

One downside to turbochargers is something called “turbo lag”, which is the delay between the moment the throttle is applied and when the turbocharger produces significant boost, providing power output.

This is primarily due to the time it takes for the turbine to reach its full speed and begin compressing air.

What Is Rolling Anti-Lag

Rolling anti-lag is a technology/system developed to reduce the effect turbo lag.

By keeping the turbocharger spooled up, maintaining boost pressure, even when not on full throttle, it significantly reduces the delay between throttle input and power output, enhancing engine response.

Rolling anti-lag is a system that allows a turbocharged engine to build boost while the car is in motion but without full throttle, such as during cornering, slowing down, etc.

This keeps the turbocharger ready to deliver maximum power without waiting for the turbine to spool up.

Difference Between Normal Anti-Lag and Rolling Anti-Lag

Traditional anti-lag systems are designed to reduce turbo lag when the vehicle is stationary, while rolling anti-lag is designed to work when the car is in motion.

This distinction makes rolling anti-lag more versatile and effective during dynamic driving conditions.

Although these two anti lag systems are different, they typically work via the same mechanisms.

History of Anti-Lag Systems

Anti-lag systems (ALS) were first introduced in the 1980s in rally racing to minimise turbo lag. These early systems were fairly rudimentary and involved a variety of mechanical and electronic components.

Over the years, anti-lag systems evolved with advancements in electronics and materials. Rolling anti-lag emerged as an offshoot, focusing on maintaining turbocharger speed while driving.

Initially, rolling anti-lag was adopted in motorsports, especially in rally and circuit racing. Gradually, car manufacturers began incorporating this technology in high-performance production cars.

YouTube video

How Rolling Anti-Lag Works

Rolling anti-lag uses the engine’s revolutions to keep the turbocharger spooled.

  1. By delaying ignition, more energy is sent to the turbocharger instead of being used for propulsion.
  2. The system adjusts the throttle position to control the air entering the engine.
  3. Controlling exhaust gas flow helps in maintaining the desired turbocharger speed.
  4. The system works in conjunction with other engine management systems to optimize performance.

Rolling anti-lag works by keeping the turbocharger in a state of readiness when the car is in motion, even when the driver is not pressing the throttle.

Normally, when the throttle is not engaged, the turbocharger slows down, causing a lag when power is suddenly needed.

This combination of processes keeps the turbocharger ready to deliver maximum power when the throttle is applied again.

Advantages of Rolling Anti-Lag

The advantages of a rolling anti lag system relies on its ability to reduce turbocharger lag.

  • Significantly reduces turbo lag, making the throttle response faster.
  • The engine is ready to deliver maximum power when back on throttle.
  • Essential in motorsports for improved lap times and competitive edge.
  • Allows the driver to fine-tune performance settings.

Drawbacks and Limitations of Rolling Anti Lag

There are several drawbacks to an anti-lag system, whether its rolling anti-lag or traditional, such as the following.

  • The system can put additional stress on the turbocharger (possibly causing damage and requiring repair on the turbo) and other engine components.
  • Keeping the turbocharger spooled can lead to increased fuel consumption.
  • The system can be noisy and increase exhaust emissions.
  • In some regions, rolling anti-lag systems may not comply with local noise and emissions regulations.

Applications and Examples

Rolling anti-lag is predominantly applied in high-performance and racing vehicles where instantaneous throttle response is critical for optimal performance.

In motorsports such as rally racing and circuit racing, anti-lag systems helps drivers maintain turbo boost during shifting, braking, and navigating through complex sections of the track, ensuring that the car is always ready to deliver maximum power.

Besides motorsports, anti-lag has also found its way into production cars, particularly in high-performance models. Some manufacturers offer it as a standard feature in their sports car models.

Though these are usually much less aggressive systems and are safer for the engine than the type of anti-lag that’s used in motorsport vehicles.

Additionally, car enthusiasts and tuners use aftermarket anti lag systems to retrofit cars that didn’t come with the technology from the factory.


Rolling anti-lag is an advanced technology that significantly enhances the performance of turbocharged engines by reducing turbo lag.

Though it has some drawbacks such as increased stress on engine components and potential environmental issues, its benefits in performance applications are undeniable.

As the automotive industry continues to evolve, rolling anti-lag will likely continue to play a significant role in the performance sector.

  • Andy Lewin

    Andy Lewin is a senior mechanic, ASE qualified master technician, and an experienced automotive engineer.He's passionate about serving the automotive community with the highest-quality and trustworthy information on all things automotive. He loves to write about car repairs, maintenance, car modifications and tuning, faults, and much more.

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