Decible levels..??

[Kinjirra]

So will finally be doing an HPDE event this year(FINALLY!!!) my only concern is my exhaust. Currently running a corsa sport and will be adding longtubes without cats in the next month or so. Wondering if anyone knows if this will be fine or how I need to test the exhaust to make sure I pass. Thanks!

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[BmacIL]

It depends on the track. Each has their own limits. I would recommend adding resonators in place of the cats. That exhaust will be similarly loud to the Corsa Xtreme with cats. At some tracks, that exhaust is fine, but many it's too loud.

 

[Kinjirra]

It will be NCM in bowling green is where im looking into going. Thanks for the info.

 

[BmacIL]

It will be NCM in bowling green is where im looking into going. Thanks for the info.

Found this:

• With the exception of special manufacturers vehicle testing, track participant vehicles are limited to 103 dBA measured 50 feet from the edge of the track. This sound limit is strictly enforced. Any vehicles exceeding this sound limit will be ordered to leave the track until appropriate corrective measures are taken to bring the vehicle into compliance.
• Track event based sound levels in the community are limited to a one hour equivalent sound level of 55.5 dBA measured at the top of every hour at a semi-permanent location in the Clark Circle neighborhood.

You may have trouble. Xtreme-equipped cars would usually flag that limit. Adding resonators will definitely help, and it'll tone down the rasp from removing the cats. The Vibrant 1794 just ahead of the muffler is a popular choice, or if you can squeeze them into the pipes ahead of the double X, that would work too.

 

[ddozier]

So will finally be doing an HPDE event this year(FINALLY!!!) my only concern is my exhaust. Currently running a corsa sport and will be adding longtubes without cats in the next month or so. Wondering if anyone knows if this will be fine or how I need to test the exhaust to make sure I pass. Thanks!

Its all about the cats, if you leave high flow cats in the system you will likely be OK, take them out and you will likely be too loud, NCM is 103db but many other tracks are regulating even lower. My target would be 99db under WOT in 3rd gear at 5000 rpm or higher measured at 50 feet behind the car using a db app on a smartphone or using a real db meter. Measuring is not easy under street conditions but are very easy to do on a dyno or at the track. NCM will give you a db reading while you are on track if you talk to the track steward before your session, but unless you are 100% sure you are under 103db I would not ask for them to give you a number. The other thing is db levels are heavily influenced by the environmental conditions of the day you are on track and are accumulative. So if you are out on track with 2 or 3 loud cars running close together that will meter out at a higher db than just the single car running on track. Air temperature and humidity have an impact on db levels measured so expect some variation in the numbers as the day goes on.

NCM has a one and done policy so if you trigger the meter you are done until you make a significant change to the exhaust system. They sell exhaust baffles in the track store at NCM but that does not always work and may not be an easy track side repair. Some of these baffles require a permanent mod to your exhaust and can damage the exhaust tips.

Good luck and let us know what you end up as an exhaust and what it measures at the track.

Dave

 

[Kinjirra]

I'll most likely have some resonators put in when I put in the long tubes. Long as they don't ruin the sound of my corsa… I don't want super loud anyway.

 

[BmacIL]

I'll most likely have some resonators put in when I put in the long tubes. Long as they don't ruin the sound of my corsa… I don't want super loud anyway.

IMO I prefer the sound of Corsa's exhausts on stock headers (or rather, header lengths). With LTs they get very trumpety. Many like that, I'm not a big fan. You could do MAK/Lethal cat deletes and have some bullet resonators put in to tame the rasp.

This is it with cat deletes:

 

[Kinjirra]

Thanks for the video...sadly most of it was the dude talking lol. I already have LT's with catless connection pipes sitting in my garage so not too keen on changing setups. I will for sure look into resonators where the cats should be to calm it down.

 

[lizardman]

After you get the long tubes installed you can go do an autoX and test the system. The http://kyscca.com/ runs sound at every event in Louisville and at NCM. The http://www.trscca.org/ might as well and are local to you.

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