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Thread: Inlet Port Flow V's Port Wall Finish

  1. #41
    Bodger

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    Re: Inlet Port Flow V's Port Wall Finish

    i don't know what you're saying with the best carb for you1100Fiat is not 55DCO; but i have a 1640cc CVH Ford, i run and tune no larger carbs then 40mm DCOE, because its the stage of engine build in for road/track.
    45's are to large with 36mm chokes. May give a tad more top-end, but not as tracktable, as with 40's on 32 or 34 chokes. To be tested when ready.
    Flowbench can be made, but impossible for me now, there is simply no room left even a simple bench model. But maybe in near future when one car is finished. But i better hurry up, cause slowly i am becoming an old farth now

  2. #42
    Spanner Monkey

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    Re: Inlet Port Flow V's Port Wall Finish

    Gid, we’re all becoming old farts lol.

    In fact we are the lucky ones✅
    Are we there yet?

  3. #43
    Racer

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    Re: Inlet Port Flow V's Port Wall Finish

    Quote Originally Posted by gid View Post
    i don't know what you're saying with the best carb for you1100Fiat is not 55DCO; but i have a 1640cc CVH Ford, i run and tune no larger carbs then 40mm DCOE, because its the stage of engine build in for road/track.
    45's are to large with 36mm chokes. May give a tad more top-end, but not as tracktable, as with 40's on 32 or 34 chokes. To be tested when ready.
    Flowbench can be made, but impossible for me now, there is simply no room left even a simple bench model. But maybe in near future when one car is finished. But i better hurry up, cause slowly i am becoming an old farth now
    This is exact what I tried to explain. When you only test on flow bench and never compare in real world you can end up with incorrect parts. I feel a flow bench is only ok to test the flow over the last part of the port where the valve is. I can be wrong but when you add carbs or trumpets you don't take into account the pulse tuning.

    I'm sure you are right about your carb size, you won't need anything bigger as 40mm. And that's what I try explain for years. people use to big carbs and chokes.

  4. #44
    Tyre Kicker 3.5cologne's Avatar

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    Re: Inlet Port Flow V's Port Wall Finish

    Quote Originally Posted by onyd View Post
    When you only test on flow bench and never compare in real world you can end up with incorrect parts.
    Totally agree

    Quote Originally Posted by onyd View Post
    I feel a flow bench is only ok to test the flow over the last part of the port where the valve is.
    I don't quite agree with this. The flow bench is a tool that can be used to check, identify and improve problem areas in the whole inlet/exhaust tract not just the head port.
    But a flow bench is only one tool in the equation with which you can check cfm and velocity at all steps of the inlet tract. As you say there are other parts to the equation like pulsing and know doubt other factors that I know nothing about.

    I'm just a weekend enthusiast trying to make improvements to what is a standard inlet tract on my V6 and I have found my flow bench to be invaluable at identifying/improving in this area.
    Also making my flow bench was a great learning curve for me and a fun project.

  5. #45
    Racer

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    Re: Inlet Port Flow V's Port Wall Finish

    I do totally agree the flow bench can check the whole inlet track but people also start measuring improvements by fitting longer trumpets or larger carbs on the same setup and that's where I find you go the wrong way. Second point is, the flow bench does not take into account pulse tuning. A VERY important factor. And this pulse tuning is a LOT more active in smaller ports.

    I've just added 4 cm longer trumpets to the existing 45 DCOE setup. I improved the whole torque line with quit a lot of Nm. No single flow bench will ever show you this. The flow bench wil probably not react to this mod. And I can do the same by leaving the trumpets at the same length but making them smaller (40mm internal on a 45 DCOE !!!).For this add the flow bench may even show a lower CFM number. Increasing the choke to 38mm was a nice lost of torque up to +/- 4000 RPM. The flow bench would probably given you a gain with this mod but the power did dropped at low RPM. ZERO gain on top

    I only try to explain, port flow is not the only thing that makes power. One thing is for sure, if you want tp do read head work, a flow bench is needed.
    Last edited by Dyno; 13-04-2020 at 19:06.

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