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Old 07-25-2011, 08:19 AM   #1
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Default Exhaust system for race only use

Hi,

Do you expect an MSM turbo with 3" exhaust and no cat, resonator or muffler would be stupid loud?

It's not for a street car and the helmet muffles a fair bit, so I guess as long as it doesn't exceed the track noise limitations it's fine.

I really have no idea what to expect, though...

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Old 07-25-2011, 11:09 AM   #2
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you will exceed the track noise limitations and I dont even know what they are.

remember also that the wastegate opens and means 100% unobstructed exhaust from valve to tip.
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Old 07-25-2011, 11:13 AM   #3
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I would say it's definitely going to be obnoxiously loud, but I don't think it will be unbearable. I ran my old miata with just a straight 2.5" exhaust for a little while before I added a resonator. Something like this is what I was running and it helped quiet the car immensely.

http://compare.ebay.com/like/1905422...=sbar&_lwgsi=y
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Old 07-25-2011, 11:17 AM   #4
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my 3" exhaust with cat, res, and 4x9x14" muffler was too loud.
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Old 07-25-2011, 11:38 AM   #5
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I think i might have a video on my youtube account of my One.Six with a straight pipe...

lemme see...
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Old 07-25-2011, 11:40 AM   #6
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Sorry for comments... but its loud as ****
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Old 07-25-2011, 11:49 AM   #7
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I had a 3.00" open exhaust with a resonator on my car when it was turbo. It was loud as hell, but it was a track car and at TWS they don't really have restrictions per say. That being said, it was much quieter than my current N/A setup with spec miata exhaust. It blew, a 117dB at HHR, but I still don't think it was read correctly. The lady was only 15 feet away, so it should be more like 105 if read correctly based on what I have seen in the past with other cars.
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Old 07-25-2011, 02:05 PM   #8
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Would a straight 4" pipe with a piece of foam stuffed in it be too loud? I am thinking of using the open cell eggcrate stuff, or an egg crate itself.
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Old 07-25-2011, 02:18 PM   #9
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You're proposing to stuff foam into a piece of pipe, and then run exhaust through it?
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Old 07-25-2011, 02:22 PM   #10
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Well I was thinking of something more like a pool noodle, with a hole in the middle.

Actually, why not something like this? With this, you wouldn't even need the pipe. It would just seal itself with that flap of tape. Also, I'm guessing it's flexible (like a pool noodle) so routing around the diff would be super easy.

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Old 07-25-2011, 02:47 PM   #11
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carry a fire extinguisher with you?

why not just buy a 4" OD resonator and shove that in your 4" pipe?
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Old 07-25-2011, 02:57 PM   #12
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Well that actually might be a good idea but how about this:

PVC pipe 4.5"
Spray expanding foam inside it
put 4" resonator inside foam
put pool noodle inside resonator
put an egg crate inside the noodle
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Old 07-25-2011, 02:58 PM   #13
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Quote:
Originally Posted by y8s View Post
you will exceed the track noise limitations and I dont even know what they are.

remember also that the wastegate opens and means 100% unobstructed exhaust from valve to tip.
I'm under 90db with no cat and the 3" "Silver Line" muffler.
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Old 07-25-2011, 03:08 PM   #14
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Just bolt on the biggest Magnaflow you can if you are worried about sound.
We run the black car with no muffler except for at Laguna Seca where we bolt up a Magnaflow and pass the 90dB sound limit (I believe the car does something low like 83dB)
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Old 07-25-2011, 03:08 PM   #15
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I know this is my first post and all, but I'm far from a newb at the track (just in the miata world)...
but noise restrictions, at a race track? I honestly didn't think that existed.
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Old 07-25-2011, 03:57 PM   #16
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Quote:
Originally Posted by MX5 GILL View Post
I know this is my first post and all, but I'm far from a newb at the track (just in the miata world)...
but noise restrictions, at a race track? I honestly didn't think that existed.
Yeah they definitely exist; especially in places where they aren't far from civilization. Harris Hill Road here in Texas has a 99dB limit at 50 ft. Laguna Seca Raceway has an even lower limit at 90dB from the sound station past corner 5 I believe because it's inside of a recreational park. A stock Porsche GT3 RS doesn't even pass the Laguna Seca noise restriction.
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Old 07-25-2011, 04:31 PM   #17
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Quote:
Originally Posted by y8s View Post
you will exceed the track noise limitations and I dont even know what they are.

remember also that the wastegate opens and means 100% unobstructed exhaust from valve to tip.
It's loud, but not that loud. The black car is ~97dB with nothing but 3" stainless from the turbo back. That's fine everywhere except Laguna (~91db limit), and I have a 22x11x5" magnaflow that knocks it down to ~84dB for that track.
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Old 07-25-2011, 04:38 PM   #18
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Quote:
Originally Posted by MX5 GILL View Post
I know this is my first post and all, but I'm far from a newb at the track (just in the miata world)...
but noise restrictions, at a race track? I honestly didn't think that existed.
Have you checked the restrictions at LRP lately? They only have like 4 unmuffled days, the rest are insanely low.
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Old 07-25-2011, 05:06 PM   #19
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Quote:
Originally Posted by Savington View Post
It's loud, but not that loud. The black car is ~97dB with nothing but 3" stainless from the turbo back. That's fine everywhere except Laguna (~91db limit), and I have a 22x11x5" magnaflow that knocks it down to ~84dB for that track.
I guess my comparison is to an open downpipe on a 2.0L turbo car.. that idled like a monster.
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Old 07-25-2011, 05:11 PM   #20
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Do you guys use ear plugs on track?
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