BMW Swirl Flaps Upgrade / Replacement & How i did it | E90 320D M47 engine (2.0 diesel)

BMW Swirl Flaps Upgrade | Replacement How i did it

Engines are complex constructions with hundreds or thousands of components working in perfect synchronisation, each component working within parameters carefully measured and imposed by the manufacturers. Even if we consider some parts more important than others, this myth is as wrong as it is bad for the engine. Each part was put there for a purpose, having a role as important as the rest of the component parts.

The same is true of the famous swirl flaps, one of the most controversial components of diesel engines since the early 2000s. And today's article is all about these flaps, today's article separates the myth from the reality.

What is the role of swirl flaps?

The swirl flaps, or "swirl flaps" in the international name, are located in front of the intake valves and have the role of creating a swirl effect in the cylinder. By creating these turbulences, the fuel is burned in an efficient manner. How is this vortex effect achieved? – The channel of an upstream valve is closed, the intake is realised only through a single valve, the admitted air will have a higher speed due to the halving of the passage section.

What are the advantages of swirl flaps?

These flaps were thought of in the early 2000s, when the auto industry began to take timid but firm steps toward reducing pollution. The transition from Euro 2 to Euro 3 was made slowly, and the swirl flaps helped by significantly reducing NOX and Hydrocarbon emissions.

But the more efficient burning of the fuel not only reduced the emissions of harmful substances, but also reduced the fuel consumption, especially for light loads encountered predominantly in urban travel. This is one of the main advantages, contrary to the common myth that these flaps have no significant utility.

Why are swirl flaps so contested?

Because they had the same problem as any new technology, namely reliability. Today's swirl flaps are much more robust, being adopted not only by BMW but also by other manufacturers such as Audi, Ford or Opel (etc). However, the swirl flaps fitted to BMW's M47 or M57 engines had a few problems that tarnished their reputation beyond repair.

The swirl flaps are held to the shaft by means of screws, which have a flattened end to take the shape of a rivet. However, as time passes and wear sets in, the bolts can break and the valves end up directly in the cylinder.
Breakage of the tabs is also caused by the weakened area near the bolt hole aided by the milling of the shaft.
Carbon deposits are another cause for concern, this clogs the intake port and puts pressure on the whole assembly. Swirl flaps are affected and can fail, coming off and ending up in the cylinder.
Both scenarios are fatal to the engine, and valve wear cannot be checked electronically, the only solution being preventive change. Many drivers, unfortunately, have chosen to completely eliminate these flaps, considering them to be a kind of appendage to the engine, a component without which the car functions the same. On the contrary, the physical removal of the flaps leads to increased fuel consumption and a higher level of noxious emissions.
Which BMW models had these fragile flaps installed?

Models with M47 engine (2.0 diesel):

Series 3 E46 318d and 320d
Series 3 E90 318d
Series 1 E87 118d and 120d
5 Series E39 and E60 520d (models up to 2006)
BMW X3 2.0d until 2006
Non-BMW models with this engine:
Land Rover Freelander from 2001 – 2006
Rover 75 from the period 1999 – 2004.

Models with M57 engine (2.5 or 3.0 diesel)

Series 3 E46 330d/330xd and E90 325d, 330d and 335d.
Series 5 E39 525d and 530d and E60 525d and 530d
Series 6 E63 635d
Series 7 E38 and E65 730d
BMW X5 E53 and E70 with the 3.0d engine
BMW X3 E83 with the 3.0d engine
BMW X6 E71 xDrive35d
Other non-BMW models with the M57 engine:
Land Rover Range Rover LR322 (2002-2006) with the 3.0 diesel engine.

Having said that, we hope we have been able to explain the importance of these swirl flaps. It is not just about our passion for BMW, as these components have a wide application on a large number of vehicles. For this reason we dedicated time and energy to come up with a new and effective solution that eliminates any fear on the reliability side.