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Thread: 906 valve and port size

  1. #1

    906 valve and port size

    I am looking for confirmation of the 906/911R valve size(s) and port size(s). I have NOS 2.0L heads that need adjustment and I want to make sure I got the numbers right before having the work done.

    Of course I have found some 'internet sources' but I'd appreciate a more 'definitive' answer/source - i can only have them re-worked once

    Many thanks for you help

  2. #2

    906

    Hello V-8

    From memory:

    Valves: 45i and 39e (same as 69S)

    Ports: 38i and 38e (really big for a 2L, lets the 906 cam do its job)

    Some 906 heads had injector ports (901/21 for the 906E with mfi) but most did not (901/20 with tall manis and 46s).

    But, do the ports 36i and 35e if you anticipate street use as you will have insufficient port velocity for any low end response with a 2L breathing through 906 sized ports.
    Early 911S Registry
    Looking for engine 960 168
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  3. #3
    Quote Originally Posted by Flunder View Post
    Hello V-8

    From memory:

    Valves: 45i and 39e (same as 69S)

    Ports: 38i and 38e (really big for a 2L, lets the 906 cam do its job)

    Some 906 heads had injector ports (901/21 for the 906E with mfi) but most did not (901/20 with tall manis and 46s).

    But, do the ports 36i and 35e if you anticipate street use as you will have insufficient port velocity for any low end response with a 2L breathing through 906 sized ports.
    Your memory is correct on the specs, but you CAN get 38mm ports with better intake velocity than the stock 36/35 ports. Modern CNC port jobs can brerathe big and create amazing velocity. My '69S heads went to Steve Weiner and got opened up to 39mm for a 2.3L motor. Look up "extreme hardcore head porn" in Search to see pics of my port job to see what I mean.
    Kenik
    - 1969 911S
    - 1965/66 911
    - S Reg #760
    - RGruppe #389

  4. #4

    906 Ports

    D shaped ports seem to be recommended for early 2.0 litre engines and I would be interested in opinions about how worthwhile this would be.

  5. #5
    Thanks guys - so far my 'sources' are confirmed. I am thinking of using the 69S valves as they fit the job - any experience to share is welcome.

    The engine (901/03) will be running with 46 Webers, 906 cams and 81.5mm PMO manifolds (RP's recommendation and furthermore, the 98mm does not fit with K&N's). Obvious potential concern is the low end response so that makes any suggestions on the 'port job' very welcome !

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