Turbocharged engines live and die by boost. The more boost, the more power — but when you lift off the throttle, that pressure drops, and your turbo slows down. Anti-lag systems (ALS) were developed to solve exactly that problem: keeping the turbo spinning even when you’re off the gas.
Originally a secret weapon in rally and circuit racing, anti-lag has now evolved into a controllable, reliable technology available to serious enthusiasts. Let’s explore how it works, the difference between throttle-jacking and fresh-air anti-lag, and how the Turbosmart ALV40 has made professional-grade anti-lag more affordable than ever — with Walton Motorsport manifolds built to support it.
How Anti-Lag Works
When you close the throttle, exhaust gas flow slows and the turbo begins to decelerate. This creates the infamous “turbo lag” when you get back on the throttle. Anti-lag systems keep the turbine spinning by maintaining energy flow — either by manipulating combustion events (throttle-jacking) or by feeding compressed air directly into the turbine (fresh-air).
In both cases, the goal is simple: maintain boost pressure between throttle transitions.
Throttle-Jacking Anti-Lag
How It Works
Throttle-jacking anti-lag — also known as ignition-retard anti-lag — keeps airflow moving through the turbo even when the driver lifts off. The ECU holds the throttle slightly open or bypasses it through an auxiliary circuit, while ignition timing is retarded so that combustion occurs late, sometimes even in the exhaust manifold.
The unburnt fuel ignites in the manifold or turbine housing, creating the signature “bang-bang” sound and a burst of energy that keeps the turbo spinning.
Pros
- Simple to implement with ECU control only
- Works with standard turbo hardware
- Highly effective for aggressive rally-style response
Cons
- Extreme exhaust heat: Turbine inlet temps can exceed 1,000°C
- Component stress: Causes cracking and warping in mild steel or cast manifolds
- Turbo life: Reduces bearing and seal longevity
- Noise: Illegal or impractical for street use
Throttle-jacking anti-lag is cheap and dramatic — but it’s brutal. It’s best reserved for purpose-built race engines and high-end materials like Inconel or thick-wall 304 stainless steel, as used in Walton Motorsport turbo manifolds.
Fresh Air (ALV) Anti-Lag
How It Works
A fresh-air anti-lag system introduces compressed air from the intercooler or charge pipe into the exhaust manifold via a dedicated anti-lag valve (ALV). When the throttle closes, the ECU opens the ALV to keep airflow moving through the turbine without injecting raw fuel or relying on post-combustion explosions.
This system is much cleaner and easier on hardware. The turbo keeps spinning because the ALV supplies fresh, oxygen-rich air directly into the hot side — maintaining spool without generating destructive heat spikes.
Pros
- Reduced heat stress: No combustion in the manifold
- Longer turbo and manifold life
- Smoother boost control
- Compatible with modern ECUs (Motec, Haltech, Link, etc.)
Cons
- More complex setup (requires ALV plumbing and control)
- Higher initial cost than throttle-jacking
- Requires a properly designed manifold
Until recently, these systems were exclusive to top-tier race teams using custom Inconel manifolds and expensive ALV hardware.
The History of Anti-Lag in Motorsport
The earliest versions of anti-lag appeared in Group A rally cars of the 1980s and 1990s. Teams like Subaru, Mitsubishi, and Ford experimented with ignition retard systems to keep their turbos lit between corners. The result? Crackling, fire-spitting beasts that defined an era.
As the technology evolved, WRC teams began refining the process — integrating bypass valves and compressed air feeds to manage turbo speed more precisely. Circuit racing followed, with endurance and touring cars adapting the concept for reliability rather than drama.
By the 2000s, full fresh-air systems became the standard for professional motorsport, using high-temperature materials like Inconel and controlled pneumatic valves.
The Rise of Affordable ALV Systems – The Turbosmart ALV40
For years, anti-lag valves were prohibitively expensive and custom-only. The introduction of the Turbosmart ALV40 changed that completely.
This 40mm pneumatic valve brought professional anti-lag control to privateers and advanced enthusiasts. Compact, durable, and built for motorsport use, the ALV40 offers:
- Direct compatibility with popular ECUs and boost controllers
- Lightweight billet construction
- Easy integration into custom or bolt-on manifolds
- Affordable pricing compared to previous ALV systems
The ALV40 effectively democratized anti-lag technology, allowing club racers, drift teams, and time-attack builds to experience true fresh-air anti-lag control.
Walton Motorsport and ALV Integration
Walton Motorsport has supported anti-lag technology since its earliest adoption in the UK motorsport scene. Our engineering team has developed bespoke Inconel and stainless manifolds configured for DSP Engineering anti-lag valves, long before ALV became mainstream.
Now, with the Turbosmart ALV40, we’re seeing a new wave of demand from customers upgrading existing setups or requesting ALV plumbing on our bolt-on stainless manifolds.
Each Walton Motorsport manifold is:
- Hand-fabricated in the UK from 304-grade stainless steel
- CFD-optimised for wastegate and turbo flow priority
- Backed by a lifetime warranty
- Available with optional ALV integration or modification
Our goal has always been to make world-class manifold technology accessible — whether you’re running a classic Mitsubishi 4G63, BMW B58, or a Toyota 2JZ-GTE.
Frequently Asked Questions
Does Anti-Lag Damage the Turbo?
Traditional anti-lag systems can shorten turbo lifespan due to extreme heat and stress. Fresh-air ALV systems dramatically reduce this risk, allowing sustained boost without combustion inside the manifold.
Can I Use Anti-Lag on the Street?
While technically possible, anti-lag produces excessive noise and heat, making it unsuitable for road use. It’s a motorsport-only feature.
What ECU Do I Need for Anti-Lag?
Most advanced ECUs like Motec, Haltech, Link, and Syvecs support programmable outputs for anti-lag control, including pneumatic ALV actuation.
What’s the Difference Between Launch Control and Anti-Lag?
Launch control helps build boost before take-off, while anti-lag maintains turbo speed between throttle transitions during driving. They often work together in competitive setups.
Do I Need a Special Manifold for Anti-Lag?
Yes. Manifolds must be designed for thermal load and gas flow. Walton Motorsport manifolds use 304 stainless steel or Inconel, designed to withstand the stress of both throttle-jacking and fresh-air anti-lag systems.
Can I Add a Turbosmart ALV40 to My Existing Walton Manifold?
Yes. Many of our existing manifolds can be retrofitted with ALV plumbing, and we offer custom fabrication options for your build.
In Anti-Lag we Trust.
Anti-lag technology has evolved from wild rally explosions to refined, engineered boost management. Thanks to products like the Turbosmart ALV40 and Walton Motorsport’s ALV-ready manifolds, genuine motorsport performance is now within reach of enthusiasts around the world.
Whether you’re chasing lap times, throttle response, or just the satisfaction of keeping boost alive between shifts — Walton Motorsport provides the hardware built to handle it.
Piqued your interest?
Watch on as Head Manifold Man Mike Walks through the implimentation of the Turbosmart ALV40 onto his Toyota 2J powerd Nissan S13!