🚩What you will read in this article:

  • What Is Swirl Flap?
  • How Swirl Flap Functions?
  • What is swirl flap delete and Why?
  • Swirl flap symptoms
  • Swirl flap delete pros and cons 
  • Which Vehicles Have Swirl Flap?
  • Swirl Flap removal software 
  • Swirl Flap delete remap cost ?
  • Swirl Flap Removal/Delete software Training 

🚩What is Swirl flap?

how swirl flaps work
Swirl flaps design

Swirl flaps are small metal valves knitted before the cylinder head intake in many modern engines. For the first time, they were installed on most BMW diesels in 2000, and ever since, they have been knitted to the engines of many vehicles, from Audi and Mazda to Mercedes and Vauxhall and other manufacturers. Engines equipped with swirl flaps have one flap per cylinder.

Swirl flaps function - swirl flap
Swirl flaps function

These flaps are made to enhance the combustion of fuel and air and to reduce emissions. Swirl flaps are made of stainless steel and are tightened into a spindle by two small TORX screws. You can easily see the O-ring and external actuating lever below the flap.

But how does the swirl flap work? We answer this very question in the following lines.

💬How does swirl flap work?

Swirl flaps were designed to reduce emissions at low RPMs and improve the combustion of air and fuel.

What we know of fluid mechanics indicates when the intake air entering the cylinder is turbulent with a high Reynolds number, the air and fuel are combined more efficiently, resulting in enhanced combustion, which, in turn, leads to reduced emissions. For this to happen, the speed of intake air should be increased. To do this, closing these valves causes the inlet air to pass through a cylinder head port and loses its speed to the decreased cross-section.

Swirl flaps location
Swirl flaps location

At higher RPMs, the flaps open to supply more air needed for that specific engine RPM. In fact, at 2000 RPMs and higher, when the flaps are complexly open, the airflow faces no resistance and is normal.

In more modern vehicles and manifolds, a vacuum-actuated electrical servo mechanism controls the opening and closing of swirl flaps, keeping the flaps closed at the lower speeds and RPMs and opening them at higher RPMs (up to around 2000 RPMs), as mentioned above.

💬 What is swirl flap delete and Why?

Despite the modifications and modernizations on the first-generation swirl flaps, for instance, the one made by BMW in 2006, the design and functioning of swirl flaps stills faces many challenges: we mention some Swirl flaps symptoms below:

Swirl flap delete pros and cons
Swirl flap delete pros and cons -swirl flaps symptoms

 1) Deposits: Given the carbon in the EGR system and the oil in the vehicle's air intake system, carbon accumulation and sedimentation can reduce the size of the intake manifold and, even in some cases, cause the flaps to stick and get jammed at different positions and RPMs, which will turn on the check lights.

2) Mechanical problems: Swirl flaps, especially metal models, have many built-in mechanical flaws, such as the loosening of the metal screws holding the flap to the spindle. Failure and breakage of these screws can cause them to fall into the combustion chamber, which will cause very severe damage to your engine, causing you significant repair costs.

swirl flap delete kit-Swirl flap delete benefits
swirl flap delete kit

3) Manifolds leak: Sometimes, long-time intense use causes the swirls flaps' spindles to fail, leading to leaking. In fact, the leak is the compressed air exiting the inlet manifold, contradicting the design philosophy of swirl flaps in the first place. Besides, this failure disrupts the fuel-to-air ratio and the failure of components, such as DPF and EGR.

swirl flaps symptoms-swirl flap removal pros and cons
swirl flap removal installation

The reasons mentioned thus far, and other reasons might make some owners think of removing the swirl of flaps. Swirl flaps can be removed manually, which will have some differences in the procedure depending on the vehicle type.

💬 Swirl flap delete pros and cons :

One of the so-called commonly known advantages of swirl flaps is increased torque at low RPMs and reduced emissions. However, if you want the truth and the whole truth, you better know that reduced emissions can be, at a large scale (let us say, across the planet), an advantage. Still, you cannot see much of a performance boost with that tiny increase in torque at low RPMs to consider it an advantage! Based on this logic, the failures that occur to the swirl flaps, as stated above, cause EGR and DPF failure and increase emissions!

The disadvantages of swirl flaps, which we addressed above, include deposits, leaks, and mechanical problems.

Given what we discussed so far, you cannot really make a fuss about those drivers and repairmen's decision to remove swirl flaps.

🚨Which Vehicles Have Swirl Flap?

swirl flaps removal software-swirl flaps delete software
swirl flaps removal software

There is a general list of engine models and vehicles with swirl flaps, such as these engines: M57, M47TU, 525d, E83, and BMWs. However, if you want to check if your car has swirl flaps, contact us so we can help. Moreover, depending on the vehicle, more specifically manifold and flap type, swirl flaps removal charges can vary.


As explained, swirl flaps are removed physically because these flaps have a direct and physical effect on the engine. But some owners prefer to remap their car after removing the flap, which although having nothing to do with removing swirl flaps, can boost your car's performance. You can also share this with our experts so they can guide you.

🚩SWIRL FLAP delete remap cost ?

swirl flap removal price differs from cars and in CaracalTech we can do it for you with the lowest price and we do our best with guarantee and support

🏁SWIRL FLAP DELETE Training Tutorial:

Here, you can learn once, fully and for good, the adjustments or removal of SWIRL FLAP  in gasoline and diesel engines. Below is a link to SWIRL FLAP training video in various software's and ECUs.

1-If you want to learn how to removal of swirl flap in gasoline and diesel engines in WinOLS and Swiftec software, you can enter to our ECU training course.

2-if you need only swirl flap OFF file, upload original ECU file in Tuning File Service, after short time our experts send you remapped file.

3-if you know remapping software like WINOLS or Swiftec, for ease and accuracy of work you can use CaracalTech Mappack in the following link.

For more information and probable problems feel free to contact us:support@caracaltech.com