Project E39 M5, Installing the Dinan Cold Air Intake

The separators are boxes behind the bumper inlet, as air enters through the bumper, most of the cold air blows around the separators but water continues into the separator.  The water drains out of these holes and flows out of the bottom of the car, the cold air diffuses around the box and lowers the temperature of the air around the filters.

Here is the water-air separator riveted in place.

We are pretty puzzled about the complication these parts add to the intake and wonder if they are really needed but Dinan is known for thorough testing and OEM-like attention to detail.  This installation is repeated on the other side of the car.

Now we can install the beautiful carbon inlet tubes.

The tubes connect to the mass airflow meters with the supplied couplers and clamps.


  1. Schrick cams and a lightweight flywheel, please. VAC Motorsports has both. They really transform the car.

    1. My experience with rwd & light flywheel, it’s most nticeable in only 1st gear, when revs build up quickly .. it’s less rotary inertia at engine speed accelleration. I found I would spin the tires more easily at take off. It may improve heal-toe shifting, depends on several other things like throttle response. Good cam up grades are winners, have done a few.

  2. Great install write up.

    It looks to be very well made, but based on the Dinan site, not sure it’s worth the trouble and expense.

    “More Power: + 5 HP @ 7000 RPM, + 4 LB-FT @ 7000 RPM (coupled w/ engine software).”

    A BMW M5 is likely to have a good intake already.

    1. We noted that the stock intake was a pretty good design. The biggest part of the equation could be relocating the intake air temp sensor as power drop due to the sensor getting hot is a pretty big deal on these cars.

      1. Out of curiosity, I would measure the air temp entering the manifold , vs at the MAF sensor, after heat soak. If the same, the hot retarded timing may be justifed for engine health?

  3. Did we ever compare these to the stock intakes
    On the dyno? I have the same set up with headers debating adding these.

Leave a Reply

Your email address will not be published. Required fields are marked *