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Thread: 4" External Discs - how to calculate flow?

  1. #1
    FlipFlop Guest

    Default 4" External Discs - how to calculate flow?

    Hi,

    I'm new to the forum and already tried the Search-function, but the results were not exactly what I'm looking for. So here I go with my question:

    I run the 4" external discs + closed end cap together with a Looney Tuned Dual Exhaust on my CanAm Renegade 800 ATV, Now I'm not sure how many discs I have to use to get the same flow as with the open end cap of the Exhaust. The diameter of the stock outlet is 2.25". How can I calculate the provided flow for each disc? How many discs do I have to use to get the same flow as a 2.25" outlet?

    Thanks for your help!
    Andreas from Germany
    Last edited by FlipFlop; 05-06-2008 at 06:04 PM.

  2. #2
    bschultz Guest

    Default

    We do not have a quick "mathmatical formula" for figuring flow per disc. On a 4" system the "open endcap" flows for 10-12 discs. What model SuperTrapp mufflers are you running (part number)? Does the Looney Tuned Exhaust have a muffler?

  3. #3
    FlipFlop Guest

    Default

    Quote Originally Posted by bschultz View Post
    We do not have a quick "mathmatical formula" for figuring flow per disc. On a 4" system the "open endcap" flows for 10-12 discs. What model SuperTrapp mufflers are you running (part number)? Does the Looney Tuned Exhaust have a muffler?
    I'm running no SuperTrapp muffler at all, only the discs and closed end cap. The 4" discs fit the Looney Tuned mufflers (in exchange for the stock mounted open end caps). The mufflers have a core of 2.25" each and the outlet of the endcap has a 2.25" diameter (with an screen type spark arrestor) as well.

    Can you give me the diameter of the outlet of your open end cap? Starting with this I can calculate how many discs I have to add to get the approx. flow of a larger diameter outlet.

  4. #4
    bschultz Guest

    Default

    The 4" open end cap has a 1.5" opening.
    May I ask what your goal is, what you are trying to accomplish?

  5. #5
    FlipFlop Guest

    Default

    Quote Originally Posted by bschultz View Post
    The 4" open end cap has a 1.5" opening.
    May I ask what your goal is, what you are trying to accomplish?
    Thanks for the info...My goal is a very simple one: Here in Germany we have very restrictive sound regulations. With the standard open end cap (2.25") the exhaust comes out at 103-105db at half throttle. Now with 9 discs I'm at 97-98db, but I don't want to give up too much flow compared to the open cap and keep sound under 100db.

  6. #6
    bschultz Guest

    Default

    If you replace the "closed" end cap with an "open" end cap you wil gain more sound.

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