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  • my plenum

    all i need to do now is have tubes and a lid welded on, and shape the holes.





    this one is not as un even as it looks

  • #2
    :shock:
    Definately not milled.
    *Ground out by a drunken monkey with a hand grinder? :twisted:
    I am here to help...

    Comment


    • #3

      That's a little closer to what you should have at the entry to each port... try and bell the mouth as much as possible as long as the radius of the bell mouth is less than half that of the radius of the port itself. Btw -- that picture is of a plenum i'm building for the toyota supra i'm working on.
      8.5 custom arias pistons (.020 over)
      eagle rods
      t70 turbo (man was that a squeeze)
      38 mm external wastegate
      mild port/polish
      3 angle valve job
      custom intercooler piping
      twin external intakes with z32 maf
      rad moved back
      3" exhaust with only a resonator
      romulator
      420cc injectors
      custom body work, homemade oil lines and fittings..
      walbro 255lph in-line fuel pump.... and lots of headaches... lol

      Comment


      • #4
        t70 wrote:
        That's a little closer to what you should have at the entry to each port... try and bell the mouth as much as possible as long as the radius of the bell mouth is less than half that of the radius of the port itself. Btw -- that picture is of a plenum i'm building for the toyota supra i'm working on.
        yea i know. it will all be smoothed out and shaped. it wasnt to hard, just time consuming

        Comment


        • #5
          hehe.. what you see in the picture is actually a steel design that i did with a drill before i got my die grinder... THAT was time consuming...
          8.5 custom arias pistons (.020 over)
          eagle rods
          t70 turbo (man was that a squeeze)
          38 mm external wastegate
          mild port/polish
          3 angle valve job
          custom intercooler piping
          twin external intakes with z32 maf
          rad moved back
          3" exhaust with only a resonator
          romulator
          420cc injectors
          custom body work, homemade oil lines and fittings..
          walbro 255lph in-line fuel pump.... and lots of headaches... lol

          Comment


          • #6
            ur job is gonna turn out better than mine, i had to leave some lifted meat around the ports and maybe a wall were the 1st hole after the elbow is

            I am hoping to get a grinder and lop it off and then do the radius's with dremel....again.



            *side note- I was talking to a local machinest whole acutally cncs heads from cast blocks of aluminum. I was gettting tips on how to go about with the raduis's and getting a top on it. And he says that you do not need to make the curves perfectly round. On a flow bench on most heads he has seen, a more multiple angle sharp edge flowed better than a nice rounded one. He pointed out that airplane wings are not perfectly smooth, the have little dowel type things that help the air stay to the wing. His advice for those was to start with a 45' and then add two more slight angles on either side. He is a pretty cool guy, kinda old school, and told me to glue sand paper to a popcycle stick. So, i am just passing it on as some potential information.

            Terrible idea putting those wheels on...

            Comment


            • #7
              we appear to disagree slightly -- i got my information from a fluid dynamics physics site. They show how the best and least turbulent flow is created by a flat surface with bellmouth intakes mounted to it and not through raised velocity stack types as seen in a magnus intake. I realize however, that turbulence is necessary and that should be acquired, in my opinion, by the sanding of the journals. I tried to find the sights again but the best flow was discovered to be at a point where the radius of the bell was exactly 1/2 of the radius of the intake tube itself using fluid dynamics software.
              8.5 custom arias pistons (.020 over)
              eagle rods
              t70 turbo (man was that a squeeze)
              38 mm external wastegate
              mild port/polish
              3 angle valve job
              custom intercooler piping
              twin external intakes with z32 maf
              rad moved back
              3" exhaust with only a resonator
              romulator
              420cc injectors
              custom body work, homemade oil lines and fittings..
              walbro 255lph in-line fuel pump.... and lots of headaches... lol

              Comment


              • #8
                Sweet, i was just passing on what chief told me.

                Terrible idea putting those wheels on...

                Comment


                • #9
                  i know.. i was also just passing on what i had learned.. i'm sure they are just 2 different schools of thought. As we all know... what works in theory doesn't necessarily work in reality all the time.
                  8.5 custom arias pistons (.020 over)
                  eagle rods
                  t70 turbo (man was that a squeeze)
                  38 mm external wastegate
                  mild port/polish
                  3 angle valve job
                  custom intercooler piping
                  twin external intakes with z32 maf
                  rad moved back
                  3" exhaust with only a resonator
                  romulator
                  420cc injectors
                  custom body work, homemade oil lines and fittings..
                  walbro 255lph in-line fuel pump.... and lots of headaches... lol

                  Comment


                  • #10
                    WaZZ300 wrote: side note- I was talking to a local machinest whole acutally cncs heads from cast blocks of aluminum. I was gettting tips on how to go about with the raduis's and getting a top on it. And he says that you do not need to make the curves perfectly round. On a flow bench on most heads he has seen, a more multiple angle sharp edge flowed better than a nice rounded one. He pointed out that airplane wings are not perfectly smooth, the have little dowel type things that help the air stay to the wing. His advice for those was to start with a 45' and then add two more slight angles on either side. He is a pretty cool guy, kinda old school, and told me to glue sand paper to a popcycle stick. So, i am just passing it on as some potential information.
                    I have also read this in different books. It is why valves are not a smooth curve and are cut at flat angles. It has been flowbench proven with valves but idk about plenum stacks.
                    KILL HADJI

                    Comment


                    • #11
                      the airplane wings have things on the trailing edge to smooth the merging of the flows, like controlled turbulence, a level of randomness without being entirely random

                      the bumpy things on a wing are called rivets, they don't weld the wings because that would be more prone to stress and fatigue, and rivets installed properly are really really strong

                      so old school bumpkins can theorize however they like... but a bellmouth will still win

                      Comment


                      • #12
                        Alex86na2t wrote: I have also read this in different books. It is why valves are not a smooth curve and are cut at flat angles. It has been flowbench proven with valves but idk about plenum stacks.
                        That's funny. A 5 angle valve job will generally outflow a 3 angle, and a radial blended 5 angle will usually outflow them both at low lifts in my experience so I'm having trouble figuring how having those flat surfaces would be better for airflow. From a fluid dynamics standpoint a bell-mouthed opening is best for flow around any radius that is shaped and sized correctly for the port..

                        Comment


                        • #13
                          sharp angles cause air to detach from a surface, so in effect a X-angled cut would actually decrease flow at certain velocities, obviously the air has to be travelling with sufficient speed and density and will behave differently at any variation

                          *add* also by detaching you have the possibility of impacting other air and causing pressure pulses in the wrong direction slowing air further, you can test this by using a funnel of the same diameter as a dispensing hose and at off angles the liquid will begin to backup

                          but in the simplest physics, a smooth curve will allow the air to plane and not create pockets of vacuum, this is why a droplet is more aerodynamic than a bullet, the trailing edge carrying the air wants to be a smooth and gentle radius

                          a water will flow faster down a ramp than it will over an equivalent height of steps (like waterfalls), assuming the same width

                          Comment


                          • #14
                            Jason84NA2T wrote: That's funny. A 5 angle valve job will generally outflow a 3 angle, and a radial blended 5 angle will usually outflow them both at low lifts in my experience so I'm having trouble figuring how having those flat surfaces would be better for airflow. From a fluid dynamics standpoint a bell-mouthed opening is best for flow around any radius that is shaped and sized correctly for the port..
                            It doesn't make any sense to me either but it is what i have read a couple times in different books.
                            KILL HADJI

                            Comment


                            • #15
                              this is out of my league and i might be totally wrong.. but i suspect that there is a possibility that the radial lengths of the valve cuts could cause a mild resonance and if the flowbench was resonant to that, then the 3 angle valve job would flow faster than a perfectly radiused valve because you could exceed 100% efficiency. Am i wrong?
                              8.5 custom arias pistons (.020 over)
                              eagle rods
                              t70 turbo (man was that a squeeze)
                              38 mm external wastegate
                              mild port/polish
                              3 angle valve job
                              custom intercooler piping
                              twin external intakes with z32 maf
                              rad moved back
                              3" exhaust with only a resonator
                              romulator
                              420cc injectors
                              custom body work, homemade oil lines and fittings..
                              walbro 255lph in-line fuel pump.... and lots of headaches... lol

                              Comment

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