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Thread: 7 Port Heads

  1. #1
    Founding Member ClassikFan's Avatar
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    7 Port Heads

    My son has been reading about Mini engine conversions featuring 7 port cylinder heads and asked me to explain.

    I am presuming that a standard Mini has 5 ports, 2 inlet & 3 exhaust, so the7 port one has 4 inlet?

    Can any experts confirm or deny please?
    Just coz you got the power... that don't mean you got the right.

  2. #2
    Lord Coco of Wigwam i_should_coco's Avatar
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    Wtf?

    Old mini or new mini? Old ones have 2 valves/cyl. New ones will be 4 valves/cyl. Only Audi / VW / etc. use 3 inlet/2 exhaust configuration AFAIK.
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  3. #3
    Moderator gjm's Avatar
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    Stuart - yes.
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  4. #4
    Founding Member ClassikFan's Avatar
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    Quote Originally Posted by i_should_coco View Post
    Wtf?

    Old mini or new mini? Old ones have 2 valves/cyl. New ones will be 4 valves/cyl. Only Audi / VW / etc. use 3 inlet/2 exhaust configuration AFAIK.
    Not talking valves, ports are the thing old chap.
    Just coz you got the power... that don't mean you got the right.

  5. #5
    Founding Member ClassikFan's Avatar
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    Quote Originally Posted by gjm View Post
    Stuart - yes.
    Thanks gjm
    Just coz you got the power... that don't mean you got the right.

  6. #6
    Lord Coco of Wigwam i_should_coco's Avatar
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    Ah... gotcha. Yeah, I remember from messing around with old minis that they had siamesed ports for some cylinders (i.e. where the firing order meant they were a cycle apart, so didn't interfere). IIRC the inlets were, and also the exhaust between 2&3 (or maybe it was the other way round?) Having separate ports would be better, but cost more.
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  7. #7
    Moderator gjm's Avatar
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    Quote Originally Posted by i_should_coco View Post
    Having separate ports would be better, but cost more.
    About 1600+VAT for a built 7-port head. Good power though - 100bhp from a 1275 is possible.
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  8. #8
    HiFi Dealer Wammer BD Audio's Avatar
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    Arden 7 port heads were the classic conversion, in reality a well worked 11 stud head is much more cost effective, there are people manufacturing 16v heads for A-series blocks these days.

  9. #9
    Moderator gjm's Avatar
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    I think there was a guy grafted the head from a BMW K100 motorbike onto an A-series block, too.
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  10. #10
    Super Dooper Wammer
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    K100 head has been done a few times now and is a nice upgrade to get 16 valves :-)

    The other benefit of the 7 port head is it turns it in to a cross-flow design whereby the inlet is one side of the head and the exhaust the other side (as opposed to all on the same side as per the original 5 port head).
    Benefit 1 is that it is meant to encourage better swirl and mixing in the combustion chamber.
    Benefit 2 is that you don't have a hot exhaust manifold stuck right next to your inlet manifold/carb.

    Buy him the David Vizard A series book - lots of info there.

  11. #11
    In the trade Wammer Samantha's Avatar
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    B16a2 conversion. Even seen it done with TBs as well (although that requires bulk head modification to fit). Lots of fun (old Mini obviously)
    How can you expect to be 'old and wise', if you were never 'young and crazy'.

  12. #12
    purplepleaser
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    Well the 7 port has the advantages of using a normal manifold and other bits so make it cheaper than the 8 port heads. Been awhile since I looked in to this as I was going to do the engine in the 60's pickup thats in the garage. Another good way for good reliability is to use a superchareger from a new mini. CArelfull of the gearboxes though, stick a twin pin diff in and it might be okay.

  13. #13
    purplepleaser
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    The best way is a bike engine in the back, supercar money for the price of a frame, engine and welding.

  14. #14
    Founding Member ClassikFan's Avatar
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    Quote Originally Posted by diceman View Post
    K100 head has been done a few times now and is a nice upgrade to get 16 valves :-)

    The other benefit of the 7 port head is it turns it in to a cross-flow design whereby the inlet is one side of the head and the exhaust the other side (as opposed to all on the same side as per the original 5 port head).
    Benefit 1 is that it is meant to encourage better swirl and mixing in the combustion chamber.
    Benefit 2 is that you don't have a hot exhaust manifold stuck right next to your inlet manifold/carb.

    Buy him the David Vizard A series book
    - lots of info there.
    Might just do that, thanks Diceman
    Just coz you got the power... that don't mean you got the right.

  15. #15
    >Insert something witty< freefallrob's Avatar
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    Vizards books are great

    I miss my old minis (cry). I always used the A series myself, didn't seem to be a mini without one!

  16. #16
    Super Dooper Wammer
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    A few friends have commented that the swap to mid engine buggers with the handling. Short wheel base, mid engined and no weight at the front makes it a "very fast rotating understeering whirly-gig" I think was the phrase. Comments were also made about sticking in lightweight engines at the front making the buggers understeer. A friend who used to race them indicated that you had to load up the front wheels under braking to get the front turned in on a std car - reducing the engine weight therefore didn't help.

    I have no experience of driving these funny engined machines myself - main comments from a guy who ran an 8 port turbo a-series

    I have had a few minis and loved tinkering with the a-series.

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