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Thread: Plenum

  1. #1
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    Plenum

    Dusting off some cobwebs as I haven't been on here for years.

    What's the current thinking on after market plenums such as

    https://plazmaman.com/product/ca18-b...nlet-manifold/

    Has anyone ever tried this or another brand and posted up performance increases for aftermarket plenums?

    Thanks

  2. #2
    Guest speedingmofa's Avatar
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    I've heard great things about plazmaman, it's a piece of art! Don't have any experience myself, but judging from the really short runners, it's great for top end, not so much for low/mid end.

    Best plenum in my opinion is still a dual plenum, which I'm building at the moment. Better low/mid/top end and proper air distribution to all chambers
    Something like this...

  3. #3
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    That looks and sounds interesting.

  4. #4
    Guest jay1017's Avatar
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    Quote Originally Posted by GTSX View Post
    Dusting off some cobwebs as I haven't been on here for years.

    What's the current thinking on after market plenums such as

    https://plazmaman.com/product/ca18-b...nlet-manifold/

    Has anyone ever tried this or another brand and posted up performance increases for aftermarket plenums?

    Thanks
    Try the CA18DET Motor Enthusiasts group on facebook. Plenty of info there.


    Sent from my iPhone using Tapatalk

  5. #5
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    I haven't found much info on there to be honest.

  6. #6
    Guest jay1017's Avatar
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    Quote Originally Posted by GTSX View Post
    I haven't found much info on there to be honest.
    Did you make a post asking?


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  7. #7
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    It's very unlikely that anyone would fit a plenum with no other mods, doing before and after dyno tests.

    Lots of pretty pictures of bling on E-bay but few of the important bits like the intake trumpets.

    Tuned length inlets use resonance to give a +ve pressure at valve opening this starts the flow moving quicker. Then the momentum of the gas flow keeps the air moving when the valve is closing to push maximum charge into the cylinder. Once the boost is high then length can be short. If you want to drive on street or cruise on M-way you need a longer inlet.

    Firing order 1-3-4-2(-1..).

    It isn't just the exhaust of a 4 that needs a twin "scroll" system. No 4 inlet opens and piston descends as 3 piston is rising and valve closes 60 degrees later. Flow into 4 is easier as it's sucking while 3 is dependent on velocity and boost to keep flow going into cylinder, so 4 robs 3 of the last bit of air. This results in an uneven effective compression ratio. Similar thing happens at 2 and 1 even with a bigger volume in plenum at front. You might find pretty CFD flow pictures but if they didn't analyse the dynamics of the valve timing sequence it's rubbish. The large volume of a tapered plenum near 1 and 2 becomes an eddy that will impede flow. Most CFD just analyse at full valve lift for all 4 intakes as though they all suck at the same time.

    Basically the V6 type twin plenum are much better while all in-line plenum have ignored the flow robbing issue and taken the simple option.

    And 3's (twin scroll 6's) with more than 240 degrees of cam don't actually have complete pulse separation. Triple scroll turbo anyone?

  8. #8
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    I have found some interesting topics on CA18DET enthusiasts now.

  9. #9
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    Dp

  10. #10
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    The GTR boys love Plazmaman plenums

  11. #11
    Guest jay1017's Avatar
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    Quote Originally Posted by MEL View Post
    The GTR boys love Plazmaman plenums
    They also do them for CA18


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  12. #12
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    Yeah but they're around 800 quid and that's not even posted/shipped at that price.

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