Exhaust baffles

[MonroeZ28]

Does anyone know if it’s possible to reinstall the exhaust baffle fuse and pass a noise decible test at the track? Or, is there a way to keep the baffles closed for the test?

[DasBaldDog]

If you mean the NPP or whatever the name is for the electronic baffle, yes there is a way to keep it closed.

In my case I wired a 3-way switch into the control wire in the trunk (based on some other threads on here). I extended the wires under the carpeting to the driver's seat. The switch is wired for 3 different modes
-Always closed (aka "Good Neighbor Mode")
-Always open (aka "I don't want to talk to my passenger" mode)
-Stock Performance

Cost me $5 for a pack of 3 way switches and about $15ish for 14awg wire to run it up to the driver's seat. If you didn't need it run that long and just wanted a quick adjustment from the trunk, you need a short amount of wire, a soldering gun (or connectors if you don't want to solder) and the switch.

Wish Radio Shack was still open (the physical stores).... great for stuff like this.

[joelster]

I cant see how it wont pass with the stock NPP setup. As loud as we think our cars are, they aren't loud at all compared to V-8 cars with aftermarket setups.

[DasBaldDog]

Originally Posted by joelster

I cant see how it wont pass with the stock NPP setup. As loud as we think our cars are, they aren't loud at all compared to V-8 cars with aftermarket setups.

Depends on the track, what levels they're using, how close the mic is, etc....

Some of the California guys used that exhaust loudness test after the whole debacle at the start of this year and our cars, GT350's, some 911's, etc are all over the 95db limit at 2500-3000 rpm (without load).

And I believe I read that GT350's routinely have problems passing Laguna on most days.

[MonroeZ28]

Originally Posted by joelster

I cant see how it wont pass with the stock NPP setup. As loud as we think our cars are, they aren't loud at all compared to V-8 cars with aftermarket setups.

Let me clarify: I have long tube headers, high flow cats, and a big cam so the car is alot louder than the stock setup.

I believe Lime Rock is a 90 db limit and they are strict about it from what I remember.

[Biergut]

Originally Posted by MonroeZ28

Let me clarify: I have long tube headers, high flow cats, and a big cam so the car is alot louder than the stock setup.

I believe Lime Rock is a 90 db limit and they are strict about it from what I remember.

I would be VERY surprised if you passed. (almost 100% certain it'll be a no go) Also -- if the event is early season they will be very diligent right out of the box coming off a long "quiet" off season. The natives get restless pretty quickly up there.

[MylesPH]

Originally Posted by DasBaldDog

Depends on the track, what levels they're using, how close the mic is, etc....

Some of the California guys used that exhaust loudness test after the whole debacle at the start of this year and our cars, GT350's, some 911's, etc are all over the 95db limit at 2500-3000 rpm (without load).

And I believe I read that GT350's routinely have problems passing Laguna on most days.

Both track days and a more aggressive policy towards loud exhausts on the street in California starting this year, have had most performance car guys looking to find a solution that’s more effective at keeping the noise down.

I might be biased, but I think its partly because of all the guys running base model four and six cylinder Camaros, Mustangs, and Challengers with the resonators cut out, and mistake being ridiculously loud with actually sounding good. But hey, If I were 22 and couldn’t swing the $ for the big motor I’d probably be guilty of the same thing...

[Supercup]

Originally Posted by MonroeZ28

Let me clarify: I have long tube headers, high flow cats, and a big cam so the car is alot louder than the stock setup.

I believe Lime Rock is a 90 db limit and they are strict about it from what I remember.

You won't be close without a lot of work - our cars are closer to 98 db stock at WOT and your set up may be as loud at 108 db.

Do they have a sound booth around the track or do they test in the pits? If a sound booth you can lift at that point, get pipes that direct the exhaust away from the sound booth - then add supertraps to the end of the pipes to further quiet it down.

If tested in the pits - you will need all of the above to pass at close quarters and even then 90 db is really low.

My GT4, stock, failed at 96 db at Laguna Seca - so I don't even bother to go to track days anymore with sound limits of less than that. I have not tested the Z for sound at any track to date.

Realistically with your set up you probably will just be frustrated going to track days with sound restrictiions at that level, as you will fail each day and be sent packing - which is no fun at all.

If your really want to make it work you will have to spend some money and when you start killing the sound with a supertrap it will start to impact how your car rev's out.

I spent a lot of time trying to meet sound at Laguna Seca over the years with turn pipes and supertraps etc. After awhile I just decided to focus on race weekends with higher limits.

Good luck finding the right balance!

[Racer56]

Originally Posted by Biergut

I would be VERY surprised if you passed. (almost 100% certain it'll be a no go) Also -- if the event is early season they will be very diligent right out of the box coming off a long "quiet" off season. The natives get restless pretty quickly up there.

I have a similar setup on my Z28 and must find a way to reduce to the Lime Rock 87db level required for muffled track days.

The shop installed a very load Borla exhaust system and I am looking for a way to reduce the noise. Borla said they can likely provide me with another muffler option.