Exhaust Silencers?

[Chris91GT]

Well, yesterday's Mosport DDT lapping day proved one thing... I have 3 weeks to come up with a way of silencing the exhaust or I am going to get "busted" for sure. The car was just a "little" too loud for Solo 1 rules (unless 95dB is a lot louder than I think it is).

Does anyone have any quick and dirty solutions? I want to retain the straight-pipe exhaust setup for lapping days and open track work on the big Mosport track, but make it easily adaptable for Solo 1. I'm thinking of trying out some cheasy baffled Canadian Tire bolt-on, or perhaps a direct bolt-up replacement for the current straight-pipe (~4') that can easily be replaced at the track, perhaps with a long, thin resonator in each pipe.

Any ideas?

Other than the Solo 1 problem... the car sounds and runs great now! :D

[TYSON]

Make some exhaust tips that point away from the tester. This will make a huge difference, at least as far as the sound meter thinks;)

What size of piping do you have? You know a single 4" tube isn't really needed unless you are looking at 700 - 800 hp, right? It may actually be detrimental to your N/A torque curve to use too large of piping.

[Chris91GT]

It's nothing radical... just 2.5" right off each h-pipe discharge. I will probably just have new bolt-on pipes bent with large resonators in them.

[TYSON]

I see you said 4' (length) not 4" (dia).

Was there a db meter, or are you just guesstimating? It'll also make a big difference if the meter is at an off vs on throttle location. (huge difference for me!) I'm hoping driver side, mid-corner for all cases.

95 db is pretty loud, especially if the meter is any distance at all from the track.

[LateApex]

Do you have mufflers and/or cats on the car?

While it sounds amazing when you pull them off a 5.0, you will not realize any meaningful performance benefit by deleting them.
The exception is if you are pushing serious power (say 350+ rwhp).

I drove a 5.0 that made over 330 ft/lbs of torque to the pavement, and did so through stock cats and Borla mufflers.

Messing around on a dyno might show one or two ponies' difference here and there, but seat-of-the-pants feel will not change dramatically on a typical (meaning off-the-shelf parts), lightly worked Mustang 5.0.

Why not just buy yourself some nice Magnaflows, Dynomax Ultra-Flo's, or something similar?

Seems like this is a headache that you could easily avoid while maintaining performance levels.

Jordan

[Chris91GT]

Tyson, there was no metre... just a guestimate. But there isn't another car running in S1 that is as loud, so I'm guessing that it's illegal. I could be completely wrong though. Perhaps the sound simply carries and doesn't actually hit the high dBs. There's no way of finding out before the first events.

Jordan, running straight-pipe over the rear axle probably doesn't show the gains that a short side-pipe setup does. With no other changes, I picked up 7kph down the Fabi-straight at SMP last summer just by cutting the mufflers out and scrapping the back-half of the exhaust. It only pegged 78dB with that setup. But it is considerably louder now with a similar setup to yo--- uh, Greg's car.

Perhaps a cheap interim solution would be to buy some bolt-on turn-down tips from CT for the first weekend to see if that helps (if it's needed). Out of curiousity, does anyone know what the dB limits are at Portland Raceway? All of the ALMS cars are forced to run turn-downs there.

[John Hannaford]

Chris,

I'll be using a set of Lobaks from RCM to replace my blown out glasspaks on the Cobra. Variety of sizes available, and they do slip ons which would be perfect for your application.

This place has some info. I don't have a Canadian source yet.

http://www.secureperformanceorder.com/onlinestore/getsubclasses.cfm?ClassID=284&CategoryID=30

[Chris91GT]

Interesting... looks like a Cherry Bomb in black. I think I'll risk it for the first weekend and do some jerry-rigging if it is too loud for the remainder of the weekend.