Laguna Seca 103db

[void_kp]

Hello folks,
I am planning to go to Laguna Seca this summer, as you know our cars are quite loud and won't pass the noise test.

I've heard about 2 options:
1/ exhaust valve controller (forza componenti B6)
2/ "laguna pipes"

but I've not found an option for the laguna pipes for the stock z/28 exhaust.
any recommendation from the hive mind?

reason I'd like to avoid the valve controller is: 1/ it will increase backpressure and temperatures, risking detonation and generally speaking harming the engine + 2/ I might still not pass the test, given my 2" headers

[Gouki]

I'll report back as I'm at Laguna on the 16th March whether temperatures increase or any issues with the Forza controller.

I might just ask the passenger to press the valves closed fob for approach to the sound station. J/k.

I monitor oil temperature throughout.

[void_kp]

online I've read that increase in backpressure at high RPM may cause knocking in addition to higher temps.
I honestly think that asking the passenger to close and open only on the climb with the sound check is probably the best bet

[ariZona28]

103 dB is pretty high. My LS3 powered C5Z has headers, no cats and a 3" LG exhaust system and I have no problems running at my local track with a 96 dB limit. You may want to download one of the many phone apps for sound measurement. Find out the distance from track to microphone and do your own "sound check". You may be trying to solve a problem you don't have.

[aris]

A stock Z/28 will pass at 103 dB, so you might not need as much mitigation as you think. I have a heavily modified one with no cats and can still pass at 105 dB, and if I’m careful with the throttle, I can get under 103 dB.


As for backpressure concerns, the minimal increase from a valve controller isn’t going to cause any engine issues. The risk of detonation or excessive heat isn’t significant in this case, especially compared to the gains in noise control. If you’re running 2” headers, you might at most need to lift slightly at T5, but it’s definitely possible to pass.

[void_kp]

Originally Posted by aris

A stock Z/28 will pass at 103 dB, so you might not need as much mitigation as you think. I have a heavily modified one with no cats and can still pass at 105 dB, and if I’m careful with the throttle, I can get under 103 dB.

hey folks, your messages fill me with hope but... I'm wondering about your car noise vs mine
Last time I measured the noise (using an iphone app) it was around 120db at cold start and that was 15ft away.

I've read online (google search) and read that stock z/28 doesn't pass 103db at Wide open throttle... I'm inclined to trust this forum more than some random comment on the internet tho.

[ariZona28]

FWIW stock Z/28s pass at AZ Motorsports Park (96dB). I've had mine in Auto X events and I've seen other folks on the road course.

[Gouki]

I was at Laguna for the last 103db HOD day with a stock Z28, no issues and never had an issue.

It's nice to know they pass a 96db.

If you're worried about knock, fill up with 96.

[void_kp]

In the end I've installed the Forza Componenti controller. Installation is quite easy... unfortunately it doesn't seem to make a significant difference. Car is noisy both with valves open and closed. Those 2" kooks headers are definitely making some (fantastic) noise. I'll try keeping valve closed and lift throttle a bit on the section with the mic.

[aris]

Originally Posted by void_kp

hey folks, your messages fill me with hope but... I'm wondering about your car noise vs mine
Last time I measured the noise (using an iphone app) it was around 120db at cold start and that was 15ft away.

I've read online (google search) and read that stock z/28 doesn't pass 103db at Wide open throttle... I'm inclined to trust this forum more than some random comment on the internet tho.

I obviously haven't heard your car, but would bet than mine is (unfortunately) louder. I have long tubes, no cats, heads, cam, and intake. If my car can pass at Laguna, I would assume that yours would.



If you're worried just lift a little at turn 5.

[void_kp]

Originally Posted by aris

I obviously haven't heard your car, but would bet than mine is (unfortunately) louder. I have long tubes, no cats, heads, cam, and intake. If my car can pass at Laguna, I would assume that yours would.



If you're worried just lift a little at turn 5.

this is VERY reassuring. yes, my car also has heads, cam but with high flow cats.

I don't have much to give an idea, but here's one:


but thank you, you have a similar setup as mine, so that gives me a lot more confidence.

[Gouki]

No issues at Laguna Seca 92 db yesterday using the Forza Controller and a willing dexterous passenger.

I'm now wondering whether the stock Z28 would pass Laguna 92db.

[King Nothing]

Originally Posted by ariZona28

FWIW stock Z/28s pass at AZ Motorsports Park (96dB). I've had mine in Auto X events and I've seen other folks on the road course.

An AutoX event with a decibel limit?!?! Wow that sucks lol jk but seriously every AutoX I’ve been to has some load AF cars, way over 120. But then again where I’ve been for AutoX is at old airports in the country. Thankfully all are fully sanctioned and scored. Fun events!

[aris]

Originally Posted by void_kp

this is VERY reassuring. yes, my car also has heads, cam but with high flow cats.

I don't have much to give an idea, but here's one:


but thank you, you have a similar setup as mine, so that gives me a lot more confidence.

Didn't realize you had a head and cam package as well!


Sounds rowdy - you will potentially need to be careful around turn 5 on a 103 event, but should be fine with that controller in place as well.