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Thread: Endcap swap on Screamin eaglre Fatshot

  1. #1
    roadglide man Guest

    Default Endcap swap on Screamin eaglre Fatshot

    I have had tuning issues on these mufflers. Talked to my tech who also does dyno tuning and has knowledge with superttapps says it is hard to make a noticeable change to the performace of the bike when running open end caps and removing only a few dics either way. So I ordered 24 new discs 12 per side. I think I may have compressed them from over tightening. Just a precaution. And also order solid endcaps. I will start at 12 like they come from supertrapp. I noticed that you guys also recommened 10 if the motor is stock. Does that mean bone stock. No high flow air cleaner or down load. Because I have the air cleaner and stage 1 download. Should I try 12 at first or will that be to lean. I hope the capping off will cause more back pressure and give me the preformace that I am looking for. Please advise.

  2. #2
    bschultz Guest

    Default

    Yes, 8-10 discs "bone" stock. Traditionally (history) tells us most OEM exhaust are restrictive and an after market exhaust will usually allow the engine to breathe better. A higher flowing air filter, means more air flow and a "staged download" should mean more fuel, which should complement each other AND the initial logic is you will need more exhaust flow; however if the exhaust flow was initially MORE than adequate the additional flow needed may already be there.

  3. #3
    roadglide man Guest

    Default

    I was following ya and ya lost me. I am changing to a closed end cap so I can create a better back pressure. A little more silent running. I guess what I need to know from you is this going to be a better set up closed with 12 or open like they came with 10. I know that with the open end it will deliver more horsepower and closed more torque. I like bottom end power. Pull is what I like. Top end is not my thing. I own a diesel truck. I like torque. Although I am not pulling or hauling anthing on my bike I like to pull away at low speeds or up steep grades with power to spare. I dont really like to rev it very high. I dont mean to lose ya. What do ya mean by more that adequate. I am a little comfused. Thx.

  4. #4
    bschultz Guest

    Default

    The flow should be adequate with 12 discs and the "closed" end cap, if you find it flat on top start adding discs. I would even try experimenting with 10 or even 8 per muffler. Make sure you use anti-seize EACH and EVERY time you swap out discs.

  5. #5
    roadglide man Guest

    Default

    Thx. I assume you mean 12 discs per muffler. When you say flat on the top do ya mean when I take it to redline? I aasume adding disc would be like adding small amounts of horsepower. I worry about it being lean with so many discs at top end speed. Although I dont ride that way. On occasion I may roll it on hard but never through the gears. I will use anti-seize each and everytime. Also I will torque them to spec 15 to 25 inch lbs. As soon as I recieve them and the weather gets better I will begin tests. Thx for the advice.

  6. #6
    bschultz Guest

    Default

    Correct, per muffler. Flat - no longer pulling or falls off on power, can be an indication of not enough exhaust flow and can be remedied by adding discs. Keep us posted.

  7. #7
    ccraig Guest

    Default

    Hi, I'm still trying to understand the use of disc's and disc count wheh using an open ended cap.

  8. #8
    bschultz Guest

    Default

    Example; You have a bike that has one of our pipes on it (w/4" discs) and it's running great but you are looking for more sound. It's currently running 20 discs with the "closed" end-cap. Remove 10-12 discs and the closed end cap and replace them with an "open" end-cap and the flow/performance/tune will remain the same; however the results will be more sound.

  9. #9
    ccraig Guest

    Default

    Right, I understand about the sound but with the open end cap the exhaust gases are going straight out the open end cap, what makes the gases want to make a 90 degree turn and go out between the discs? When using the open end cap what need is there for the discs?
    Thanks

  10. #10
    bschultz Guest

    Default

    The size of the hole in the open end cap is smaller than the disc hole and core diameter. The exhaust gases exit the open end cap at a specific flow rate with the excess gases exiting the discs.
    Last edited by bschultz; 10-22-2009 at 07:12 AM. Reason: add

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