CNC Machined alumimum inserts for 6-port sleeves found in all non-turbo 13B rotary engines from 1984 through 1991. These are also referred to as "Auxiliary Ports" or "5th & 6th Ports".

Inserts improve airflow to auxiliary ports, increasing top-end power. The difference is noticeable, even by the seat of the pants. Typical improvement is about 8hp, but results vary. Mazda implemented a similar solution for the RX-8 6-port sleeves, by casting a radiused shape into the end of the sleeves. We just beat them to it by several years.

We now include replacement cross pins. Our ultra hard, CNC machined pins are manufactured from A2 alloy steel, then hardened and nickel plated for extreme wear resistance.

Installation of the inserts to the 6-port sleeves only takes about 5 to 10 minutes, presuming the sleeves are clean. Carburettor cleaner does the best job at removing carbon-buildup from sleeves. Step-by-step written instructions with pictures are provided. You may also download the PDF instructions below.

Installation in engine requires removal of lower intake manifold. Does not require disassembly of engine block or removal of engine from engine bay. Typical installation takes about 2 hours. We recommend that you take the opportunity to replace your lower intake manifold gasket at the same time, since there is a risk of damaging it when removing the lower manifold and any vacuum leaks caused by a damaged gasket will require you to go back in there later to fix. It may also be a good time to replace your primary injector seals, as long as you are in there.

Additional Information

>> Click here to download instructions for installing 6-port inserts into sleeves