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Thread: Supertrapp for Wastegate?

  1. #1
    jkstill Guest

    Default Supertrapp for Wastegate?

    I am looking for ways to quiet down my car to meet noise regulations for SCCA and other events.

    The car is a 93 Mazda RX-7 single turbo, HKS Wastegate and TO4S turbo with .82 AR.

    The exhaust system is fairly well muffled, with a Racing Beat Catback and and a Magnoflow muffler in the catback.

    The problem is the wastegate, which dumps to atmosphere. At WOT it is quite loud.

    I have been considering some options to reduce the noise. One option is to plumb the WG back into the down pipe in the exhaust. I'm not too keen on that idea as it seems overly complicated, and possibly robbing too much power.

    Some have suggested using the disc only Supertrapp on the wastegate pipe. The problem is I don't know just how much back pressure that will create, and if the HKS wastegate can handle it without incurring boost creep.

    Any experience or suggestions regarding this?
    Last edited by jkstill; 02-23-2010 at 05:17 PM. Reason: typo

  2. #2
    bschultz Guest


    We have not done any R&D or experimenting with wastegate muffling. Plumbing back to the exhaust is the most common solution.
    If you do consider experimenting, I would defiantly weld the unit on (rather than clamp it). I would purchase an extra 12 pack of discs (for more flow) and reduce from there if needed. I would also consider selecting a unit which the inside diameter of the disc (and/or muffler core) equals or exceeds the pipe diameter you'll be attaching it to (no unnessary restictions).

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