HomeForumsTechnical – GeneralEngineEcotec super6 concept

This topic contains 6 replies, has 3 voices, and was last updated by Profile photo of klampykixx klampykixx 2 years, 7 months ago.

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  • #20243
    Profile photo of klampykixx
    klampykixx
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    Member since: May 16, 2015
    Posts: 164

    Hi guys I’ve been thinking.

     

    Would an L67 or even a basic ecotec in supercharged form (specifically a positive displacement blower) benefit from longer intake runners at all?

     

    What I’m thinking is to use the stock eco plenum but make up a new lid for a charger to sit on top of.

     

    Obviously this wouldn’t fit under a bonnet but I’d be using it on a drift car so poking out could be a cool feature.

     

    Basically trying to establish Wether long runners are of any benefit on a boosted motor as opposed to super short like a stock L67 manifold.

    #20253
    Profile photo of [TUFFVQ]
    [TUFFVQ]
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    Member since: March 2, 2015
    Posts: 171

    No.

    #20254
    Profile photo of [TUFFVQ]
    [TUFFVQ]
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    Member since: March 2, 2015
    Posts: 171

    Ok I’ll elaborate.
    The reason for longer runners is due to resonance within the pipe during airflow. In naturally aspirated form, when the airflow hits a harmonic the resistance to flow is mildly reduced, which assists the charge air making its way into the cylinder.

    For example, on my manifold I have a 10″ runner from bellmouth to valve head. This should give a 2nd order harmonic at about 5000rpm. This is longer than the 8″ runner on a VN Group A manifold (of which I replicated the plenum and general layout) which has the same harmonic a bit over 6000rpm. For a street engine the longer runner works better for my application. The longer the runner, the lower rpm the 2nd order harmonic occurs at. The higher the order the harmonic, the less impact it has (1st order is stronger than 2nd etc.)

    Boosted engines have no need for these effects as the air is being forced in so the gain from a harmonic is negligible. The only reason to run a some length of ‘runner’ is to try and reduce the turbulence in the runner for more effective cylinder fill.

    For more reading, look up ‘Standing Waves’ or ‘Harmonics’.

    #20255
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    sands vs
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    Member since: March 1, 2015
    Posts: 575

    L67s are making 300rwkw plus on e85 now so I think your time and money could be better spent

    #20266
    Profile photo of klampykixx
    klampykixx
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    Member since: May 16, 2015
    Posts: 164

    Was asking purely to do away with having to buy a manifold and heads.

    Wondering if there would be a measurable difference or not

    And then to add to the first post, how it would behave once a turbo is included in the setup, like compound boost.

    And would having a larger plenum under the blower affect intake temps at all? Or would a cooler still be required?

    #20323
    Profile photo of [TUFFVQ]
    [TUFFVQ]
    Participant
    Member since: March 2, 2015
    Posts: 171

    Was asking purely to do away with having to buy a manifold and heads. Wondering if there would be a measurable difference or not And then to add to the first post, how it would behave once a turbo is included in the setup, like compound boost. And would having a larger plenum under the blower affect intake temps at all? Or would a cooler still be required?

    Have a solid think about the questions you’re asking first before I start typing out more information….

    #20336
    Profile photo of klampykixx
    klampykixx
    Participant
    Member since: May 16, 2015
    Posts: 164

    So the main Q was answered,  which is longer runners are of no specific benefit to power production/response opposed to short runners.

    Second Q.Does a larger plenum still require intercooling compared to a smaller one.

    Third Q. If a turbo was feeding a blower via a fmic,  would the blower still also need to be intercooled therefore making the fmic redundant but still needing a cooler to then be post blower, ie: intake>turbo>blower>intercooler>Tb>plenum.

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