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 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 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 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 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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