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Thread: Q. Flow rate (cfm) of 4" disks

  1. #1
    RCS Guest

    Default Q. Flow rate (cfm) of 4" disks

    Hello

    On another MC forum I found the following "supposedly" attributed to Supertrapp:

    "The flow rate of the SuperTrapp SuperMeg with 14 discs and closed cap is 190 cfm.
    Each disc added or subtracted is equal to about 10cfm.
    Muffler reaches max cfm with 25 disc and a closed cap-about 300. After that, you would have to go to 12 disc and an open cap, this is equivalent to about 290-300 cfm. With the open end cap in place the effect of each disc is lessened to about 5cfm per disc."

    Now my questions are;
    1) is the above accurate? If not, what are the accurate cfm flow rate values.

    2) are the above cfm values for both open & closed end cap disc use (5 and 10) also for Fatshotz's?

    3) If accurate then why does max cfm of 300 with 25 discs and a closed cap measure out to 12 cfm per disk ?

    4) If 12 disc and an open cap is equivalent to about 290-300 cfm, then subtracting the 5 cfm disc value for 12 open end cap discs (60), that means the open end cap itself flows the remaining 230-240 cfm. To match that open end cap flow value for use with a closed end cap, I would need need to add 23-24 discs not the 10-12 that is universally recommended.

    I am trying to accurately convert my Stage 1 103 RGU which was dyno tuned with a open end cap to the equivalent flow value in a closed end cap configuration.

    thank you,

  2. #2
    bschultz Guest

    Default

    The info you have obtained/provided was a response (see below) to a specific customer query regarding a 2:1 SuperTrapp SuperMeg system several years ago, and for the most part correct. Keep in mind however, the exhaust flow will follow the path of LEAST resistance, which the "open" end cap provides.

    THE FOLLOWING INFORMATION IS STATED IN AVERAGE FLOW. EACH MUFFLER ASSEMBLY/DISC COMBINATION IS SUBJECT TO PRODUCTION TOLERANCES, VARIATION IN DISC INSTALLATION, AND DIFFERENCES IN TEST EQUIPMENT AND TEST CONDITIONS. ALL OF THESE FACTORS CAN AFFECT FLOW RESULTS.
    Typically each 4" disc is worth about 10cfm when using a closed end cap. The flow rate of the SuperTrapp SuperMeg with 14 discs and a closed end cap is 190cfm. This rate would increase by 10cfm for each additional disc. (15 discs = 200cfm, 16 discs = 210cfm, etc..) This muffler reaches maximum flow with 25 discs at 300cfm. After 25 discs you will need to drop back to 12 discs and an OPEN end cap. This configuration will take you back to a flow of about 290cfm. With the open end cap the flow increase drops to about 5cfm per disc and total muffler flow is maximized with 18 discs at 325cfm.

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