Tech Tidbit: BMW N54 Stock Air Box vs. DCI

During AccessPORT development on the dyno with a 2008 BMW 135i, we had the opportunity to do some back-to-back intake testing on a dual-cone intake (DCI) vs. the stock BMW airbox. The only other modification to the car was a catback exhaust.

I used an AccessPORT Off-The-Shelf Stage1 93 Octane v202 calibration for the testing to maintain a consistent tune with the only variable being the intakes. All runs were completed within 30 minutes of each other with the car being run until the power became consistent run-to-run. Charge Air Temps were started at 115F degrees for each run.

The DCI intake was tested first, as it was already installed on the car. The DCI was then quickly swapped out for the stock intake and tested again. The dyno graph shows the stock intake made the same peak HP as the DCI, and made slightly more torque in the low-end and at peak.

As a final test, the top of the stock airbox was removed. The dyno graph shows appreciable gains in HP and torque across the entire power band over the stock intake and the DCI. This shows that there is power to be gained over the stock intake when restrictions are removed.

I will try to post more interesting info as I continue to play on the dyno and these opportunities come up. At the moment I’m neck deep in BMW AccessPORT development!

– Rob Irish
COBB Tuning BMW Engineering Team


  1. Brian Peterson says


    The big problem I see with dynamometer testing intakes is that the hood is always open whereas on the street it never is.

    Multiple pass two way timed runs are much more indicative of actual road performance.

  2. Irish says

    Hi Brian,

    We do all our testing on the dyno with the hood closed as if we were on the road.


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