BMW 3-series and 5-series AFM Adapter (M20/M42 engines)


Sold Out

SOLD OUT, but a lighter second generation adapter is in the works!

BMW 3-series, 5-series equipped with M20 and M42 engines have an air flow meter (AFM) with a square inlet. Our intake adapter provides a smooth transition from circular to square, so you can fit your own cone filter element or turbo plumbing. We have seen adapters that transition abruptly from a circular to square cross section, and while this is a cheaper solution, it creates turbulence and can end up flowing worse than the stock setup. You can read our in-depth article about why cheap intake adapters perform poorly here.

A bead on our adapter inlet allows for a hose or cone filter to be hose clamped on. TIG welds and a powder coat finish provide good looks and durability.

Note that replacing the stock air box with our adapter will require custom mounting to support the AFM and intake plumbing. If mounting a cone filter, a heat shield or air box is recommended. Gasket included.

Overall length: 2.75 inches

Inlet outer diameter: 2.5 inches

Applicable vehicles: BMW 318i/iS (E30 1989-1995), 318ti (E36 1992-1995), 318iC (E30 1991-1992; E36 1996-2000), 325e (E30 1985-1988), 325i/iS/iC (E30 1985-1991), 325iX (E30 1985-1990), 525i (E34 1989-1990), 528e (E28 1982-1988)