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Cyclone prefilters


We have all seen or heard about Cyclone Prefilters, but in many cases we are completely unaware of this great ally to our snorkel. In SNORKEL4X4 we present this article to answer every question you may have and to find out how beneficial it can be for your 4x4 engine.




The Cyclone Prefilter takes its name from the effect that air produces while flowing inside it, creating a truly centrifugal cyclone force to separate air and dust, so obtaining optimal filtration. The dust will be decanted to the side of the transparent bowl or will be directly evacuated outside depending on the Cyclone filter type.

It is because of the prefilter’s base and the fixed blades' design that air will enter, spinning in the bowl, where impurities will be centrifuged and then evacuated or drained to the lateral through the space between the bowl’s top and the upper cover.

Air and dust enter the prefilter from its lower base, spinning around thanks to the design of its leaning fixed blades which causes this circular motion.

Due to the huge centrifugal force of air spinning at high speed, dust decants and is separated from the air from the far sides to the top side.

Dust decants to the bowl’s lateral container, going through the tiny space between it and the top cover.

Once it is clean, air vertically descends through the freeway which remains inside the cyclone without affecting its motion.

The prefiltered airflow enters the snorkel through the connection between both elements, ready to suitably feed our engine.



So, when do we need to fix a cyclone prefilter? It should be considered that standard heads are the ones that offer a higher on-road performance for normal use due to their frontal airflow design, which provides a very beneficial overpressure for engine intake.

Now, from the very first moment we drive in dusty or very dusty environments such as forest trails, or in several vehicles, desert, works and construction projects of any kind, etc., these are the conditions which make the cyclone head an essential element.

If we don’t use the prefilter, the dust suspended in the air will get into the vehicle’s filter filling it and raising the fuel consumption, lowering the engine performance or may even break it. It is under these circumstances that we will change the standard head for a cyclone one if we hadn’t anticipated them before.

Usabilidad Cyclones





Decantation prefilters are the most popular cyclones among users due to their good performance, different sizes and capacities and economic prices. Filtered dust is decanted to the bowl’s lateral space for its later emptying.

Donaldson is the best known brand thanks to its quality and for being the creators of the current design, which has later been emulated by different producers.


PARTICLE PREFILTER: 75% (Donaldson) - 60% (Chinese)



WEIGHT: 700-1.600 g

CAPACITY: 5-9 m³/min



These feature automatic emptying which doesn’t need any kind of maintenance.

It has a similar interior to decantation models but includes some opening shaped slots to evacuate dust to the outside. Some models also have an additional external case to lower the turbulences which could interfere with their proper functioning. They are less popular due to their low flow.



EMPTYING: Automatic

MAINTENANCE: Not required

WEIGHT: 700-1.800 g

CAPACITY: 5-6 m³/min



Stands out for its full capacity on prefiltration to increase performance.

By far the most capable and effective model. The inertia turbine in its interior increases and empowers the centrifugal force, improving prefiltration and vehicle performance due to air overpressure. It is the patented Donaldson’s TopSpin system.


PARTICLE PREFILTER: 85-99% (Test ISO 5011/SAE J726)

EMPTYING: Automatic

MAINTENANCE: Not required

WEIGHT: 600-1.300 g

CAPACITY: 6-13 m³/min



The most important thing to take into account when choosing a Cyclone prefilter to not restrict engine performance is the maximum airflow level capacity (m³/ min.), depending on our 4x4 engine’s cubic capacity and the maximum revolutions per minute which should operate under.

As an example, a vehicle with a 3 l. engine with a maximum RPM of 3.500, will need an airflow volume of 10.5 m³ (3x3.500) / 1000. At a maximum of 3.500 it will need of 9 m³ / min. Moreover, an appropriate capacity will make centrifuge forces inside it optimal to air filter.

The following table shows the air volume your engine needs, just enter the cubic capacity and its maximum RPM. It is important to remember that under normal use the engine spins at low turns, but we will need more at key moments such as overtaking on road, high power needs while off-roading (sand dunes, deep mud, etc.) so we recommend you to think twice before introducing maximum RPM:

Tipo de Motor

Cubic Capacity (cm³)

Max. RPM

Flow m³/min

We were surprised to see the spectacular preparations for big 4x4 vehicles with cyclone prefilters that don't even get half the needed capacity for their engines, an unfortunately common fact for many users given their lack of awareness.

We hope this information will be useful for you in order to take a good choice for keeping enjoying dust with the best performances.