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  • emodspitfire

    Dec. 8, 2008 11:01 a.m. emodspitfire New Reader

    Folks,

    Can anyone direct me to a design handbook or GRM/SCCA/etc. articles on quieting down racecars?

    The racecar blew out the Db meter 3x in CO springs and I DO want to be a good citizen going forward. (Grin)

    The car is currently using glasspacks (Not old) and I added steel wool, 2x to try and pass the sound test.

    TIA,

    Rog Smith

  • Autolex

    Dec. 8, 2008 11:14 a.m. Autolex Reader

    Try the supertrapp muffler/plates. (I think Keith used these on the seven?)

    Try Summit Racing

    or

    Something like this maybe?

    maybe someone else can chime in and help out on this one?

  • P71

    Dec. 8, 2008 11:18 a.m. P71 HalfDork

    The Dynomax Welded Bullet mufflers are pretty quiet for straight-through racing mufflers. Us rotary guys love them!

    http://store.summitracing.com/partdetail.asp?autofilter=1&part=WLK-24215&N...

    I just bought that one for my 7 and I had the 3" version on my Turbo Coupe.

  • John Brown

    Dec. 8, 2008 11:35 a.m. John Brown SuperDork

    I have used multiple inline diffusers on a car with an "open" exhaust and it has wirked well. Go to Summit or Jegs and search their race mufflers. It is a little screen device that rivets into the pipe. It will cause a small amount of backpressure but will reward you with a small amount of torque.

  • Keith

    Dec. 8, 2008 12:44 p.m. Keith SuperDork

    Do you have dyno charts of a torque improvement from improved backpressure? Because I have just the opposite :)

    I used a "SuperTipp" (my own nomenclature, Google will probably fail you) on the Seven to cut the sound levels when required. It's simply a "disc only muffler" that I slip over the end of the exhaust pipe, and a bit of testing with the local track's sound meter let me figure the perfect number of diffusion plates.

  • Autolex

    Dec. 8, 2008 12:55 p.m. Autolex Reader

    Keith wrote: I used a "SuperTipp" (my own nomenclature, Google will probably fail you) on the Seven to cut the sound levels when required. It's simply a "disc only muffler" that I slip over the end of the exhaust pipe, and a bit of testing with the local track's sound meter let me figure the perfect number of diffusion plates.

    Something like this?

  • walterj

    Dec. 8, 2008 1:04 p.m. walterj HalfDork

    It helps also to point the exhaust into the road away from the meter - leave the elbow loose so it can swivel....

  • SoloSonett

    Dec. 8, 2008 1:08 p.m. SoloSonett Reader

    I'm using a pair of these on the SoloSonett ( L98 powered)

    http://store.summitracing.com/egnsearch.asp?N=700+115+302989&D=302989

    very adjustable for different tracks or AutoX sites

  • Keith

    Dec. 8, 2008 1:18 p.m. Keith SuperDork

    Autolex wrote:

    Keith wrote: I used a "SuperTipp" (my own nomenclature, Google will probably fail you) on the Seven to cut the sound levels when required. It's simply a "disc only muffler" that I slip over the end of the exhaust pipe, and a bit of testing with the local track's sound meter let me figure the perfect number of diffusion plates.

    Something like this?

    Yeah, that's basically it.

 
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