Air suction manifolds are easy to install in every kind of filter box or wherever more airflow is required. After customizing a motor or after increasing the turbine pressure one always has to face the problem of the filter box that cannot supply the air the motor needs. This happens because in the motor there is not much space and because the filter boxes are too small. Remember that for a good working of the motor during intake stroke the filter box should contain between 19 and 21 times the unitary displacement.

Example:
A motor with four cylinders and 2000 cc displacement has a unitary displacement of 500 cc. Then the filter box should contain 500x19=9500 cc, that is 9.5 litres. Measure the capacity of your box and you will see that you will never have the flow needed.

The manifold can in no way increase the volumetric capacity of the box, but it enables it not to depress when the motor reaches the peak of suction, that is to say in the peak of torque, by supplying a supplementary suction inlet.
Now someone could think that it would be sufficient to make a hole in the box without spending money on manifolds. This could be theoretically done, but a hole of 50 millimetres would react, because of the produced turbulences, like a hole of 20 millimetres that sucks air in a chaotic and whirling way worsening and not improving the motor breathing. The manifolds are available in three standard measures:

• Short: H 3.3 cm, hole in the box side 40mm
• Medium: H 6.8 cm, hole in the box side 40mm
• Long: H 11.2 cm, hole in the box side 40mm