Swirl Flap Removal

swirl flap removal angus scotland brand autos

Modern diesel and petrol engines contain small butterfly valves known as swirl flaps, which are situated within the inlet manifold. These flaps aid in regulating the fuel to air ratio, improving emissions, and generating better torque at low engine speeds. During light engine loads, the flaps close, causing air to swirl into the combustion chamber, enhancing combustion and helping to improve emissions and generate more torque. Once the engine reaches 2000 rpm, the flaps are typically fully opened, having minimal impact on engine performance and emissions.


What are the problems?

Major Mechanical Failure:
Certain vehicles, especially early BMW models, were equipped with metal flaps that were susceptible to failure. The screws securing the flap to the spindle would loosen and enter the combustion chamber, leading to severe engine damage.

Leaking Manifolds
Over time, the seals surrounding the flap spindle can break down, causing pressurized air from the inlet manifold to leak into the atmosphere. This loss in boost pressure can cause the vehicle to run rich and damage other components such as DPF and EGR.

Carbon build up:
The EGR system’s carbon and oil from the breather system can cause carbon to accumulate on the flaps, reducing the intake manifold size and potentially impeding performance.

Electronic actuators:
Modern manifold designs employ an electronic actuator to open and close the flaps. These actuators and position sensors may malfunction, resulting in the flaps staying closed and impairing performance. This can trigger an engine management light and, in some cases, activate limp mode.

How do we remove them?

The approach for removing the flaps varies based on the design. In some instances, the manifold must be unbolted to physically remove the flaps. Alternatively, if the flaps are in good mechanical condition, and the problem is with the electronic actuator, the actuator function can be deactivated, and the flaps can remain in place.

What are the negatives?

We believe that removing the flaps has little impact, as the reduction in emissions and performance at low engine speeds is barely noticeable, and only relevant if there is no carbon buildup. Carbon buildup starts as soon as the vehicle is manufactured, so removing the flaps would likely enhance performance and efficiency.

What does it cost?

The cost of removal depends on the design of the manifold and flaps, contact us with your vehicle registration and we will be more than happy to offer a quotation.

Scroll to Top