emodspitfire
emodspitfire New Reader
12/8/08 11:01 a.m.

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
Autolex Reader
12/8/08 11:14 a.m.

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
P71 GRM+ Memberand HalfDork
12/8/08 11:18 a.m.

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=700+4294923429+400358+4294922711+4294922710+115&autoview=sku

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

John Brown
John Brown GRM+ Memberand SuperDork
12/8/08 11:35 a.m.

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
Keith GRM+ Memberand SuperDork
12/8/08 12:44 p.m.

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
Autolex Reader
12/8/08 12:55 p.m.
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
walterj HalfDork
12/8/08 1:04 p.m.

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

SoloSonett
SoloSonett Reader
12/8/08 1:08 p.m.

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
Keith GRM+ Memberand SuperDork
12/8/08 1:18 p.m.
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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