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Sound level readings at NCM Motorsports Park 2021


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These are the official readings from the Friday morning practice.  Taken by the official sound meter dude at NCM.

 

9.14. NOISE LIMIT
9.14.1. ChampCar’s basic noise limit for FOR ALL EVENTS is 96 dB at 50 feet from the track. Certain events may impose a tighter noise restriction – check all event supplemental rules. Excessive noise will result in a black-flag and require repair prior to being re-admitted to the race. A second offense will result in disqualification and removal from the event.


516 -91.5

902 -90.1

49 -84.7

152 -81.1

630 -101.2

556 -80.2

86 -98.4

112 -89.1

605 -91.3

959 -90.7

339 -83.8

666 -92.3

528 -78.3

606 -77.2

55 -101.7

341 -86.1

266 -94.8

117 -87.2

668 -100.7

900 -87.2

160 - 83.0

172 -98.3

253 -92.3

970 -91.0

105 -82.2

300 -86.4

352 -95.9

383 -93.9

793 -91.6

640 -92.4

901 -75.2

798 -88.3

670 -89.7

918 - below 90-... way below

717 -88.7

252 -88.1

959 - reading not taken

429 -reading not taken

983 -95.3

600 -86.6

545 -92.6

700 -80.2

511 -103.1

797 -88.7

107 -87.7

1 - 96.4

527 -100.7

 

 

All cars testing in the morning that were over the 96 dba limit were told what they needed to do. All cars over the tracks 106103 limit were called into and told to fix before they returned to practice.
 

 

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Remember. Just because you are racing at Daytona does not mean that you show up with open exhaust. You will fail, and be black flagged until you quiet the car down.

I will be on the Daytona pit lane with my amazon purchased Chinese made and assembled sound meter. It will have fresh batteries.
 

some helpful links
https://daytonaconverter.com/

https://www.autozone.com/

 

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Which side of the track will they be metering from for the tracks?

Our car is quieter with a side exhaust than it is with a spec miata exhaust, but it points directly at the sound station.   We use a muffler that is advertised as a moderate tone street muffler and we registered 101.2 before the silencer.  

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58 minutes ago, Bill Strong said:

Remember. Just because you are racing at Daytona does not mean that you show up with open exhaust. You will fail, and be black flagged until you quiet the car down.

I will be on the Daytona pit lane with my amazon purchased Chinese made and assembled sound meter. It will have fresh batteries.
 

some helpful links
https://daytonaconverter.com/

https://www.autozone.com/

 

If you are going to actually try and get accurate readings of individual cars, New Chicane

Instead of pit lane, set up between turn 2/4/6 50ft from the track...  Pit lane does not allow for any isolation of other factors that should be considered when measuring sound.  FYI, this is part of my real world job...I'm sure @55mini could give a lot of advice as he has 45+ years in the field of acoustics and acoustical measurements....

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17 minutes ago, hotchkis23 said:

 

If you are going to actually try and get accurate readings of individual cars, New Chicane

Instead of pit lane, set up between turn 2/4/6 50ft from the track...  Pit lane does not allow for any isolation of other factors that should be considered when measuring sound.  FYI, this is part of my real world job...I'm sure @55mini could give a lot of advice as he has 45+ years in the field of acoustics and acoustical measurements....

Why not the outside of T3 exit going to T4? I say that assuming you want to be far from cars that you aren’t intending to measure to cut down on background noise, and you want to be in a full throttle zone. In the 2/4/6 area wouldn’t you hear cars from all those sections and it may be hard to isolate a single car?

What kind of sound blocking should you employ to cut down on hearing cars behind you?

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Just out of curiosity, I have run quite a few tracks and been in the series for 5+ yrs. Don’t ever remember sound being that big of an issue.  Is the sound issues being questioned enforced by the tracks or is this champcar enforcing it? Where’s Bill?😂 

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1 hour ago, enginerd said:

Why not the outside of T3 exit going to T4? I say that assuming you want to be far from cars that you aren’t intending to measure to cut down on background noise, and you want to be in a full throttle zone. In the 2/4/6 area wouldn’t you hear cars from all those sections and it may be hard to isolate a single car?

What kind of sound blocking should you employ to cut down on hearing cars behind you?

T3 could work too, but being in the sweet spot that I pointed out, you would have 3 separate opportunities to really get a good reading on a car that might be borderline.  Think of it more as a range of motion that you could move between to get the best readings.  Basically anywhere in that area that you want to choose should work and give an accurate reading.  Another spot would be on the inside of nascar 3 and 4, but you would want a mic on a boom about 10-15ft. in the air, 50 ft. from the wall to measure the sound.  Or just put Bill in a scissor lift...😉

Edited by hotchkis23
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  • Technical Advisory Committee

Nothing to see here, just another thing thats "not changing"

 

NCM's sound limit is 106, but for some reason champcar decided to enforce 96?

 

I assume this was taken away from all walls and buildings, with the cars by themselves on that section of track?

 

Damn, lots of teams racing this weekend with no mufflers.  Just put a muffler on the car.

Oh wait, Belittling customers might be a bad thing.

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11 hours ago, Chris Huggins said:

Nothing to see here, just another thing thats "not changing"

 

NCM's sound limit is 106, but for some reason champcar decided to enforce 96?

 

I assume this was taken away from all walls and buildings, with the cars by themselves on that section of track?

 

Damn, lots of teams racing this weekend with no mufflers.  Just put a muffler on the car.

Oh wait, Belittling customers might be a bad thing.

I saw a team that had a sound violation on Friday, got told, put a baffle in it before their muffler, I helped weld it in and were fine with being below when they went out again. They had a muffler and a baffle. The track sound limit is 106db. For some reason during the race when measured again it was above the 96db limit. They got black flagged, cut up the tip some to try to fix it, but ended up changing the driving strategy to not hit the db meter there in that turn.

 

I wonder what happens here and why? The team did what they were supposed to do and tested and passed, then in the race got black flagged. As Bill says, they have a muffler, and with a baffle they had two. I am dumbfounded as to why this happened and why Champcar did not know about it to work with the team on a solution instead of potentially ruining their entire weekend. I think there should have been a better solution here and hopefully we can learn from it. Maybe have an official come down and talk with the team, have the team go up to race control and explain what was happening and what transpired before they basically ended the race for the team. It just does not sit well with me.

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I am glad that I posted the actual rule in the BCCR so that Chris Huggins could read that and know that ChampCar is enforcing the 96db limit. Here, let me post it again.

 

Quote

9.14. NOISE LIMIT
9.14.1. ChampCar’s basic noise limit for FOR ALL EVENTS is 96 dB at 50 feet from the track. Certain events may impose a tighter noise restriction – check all event supplemental rules. Excessive noise will result in a black-flag and require repair prior to being re-admitted to the race. A second offense will result in disqualification and removal from the event.

 

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46 minutes ago, DEE DEE said:

The sound limit used to be 103 db at 50 ft,  and the average limit was 55db per hour at NCM.  So they graciously increased it for this event to 106?

 

 

yes. sorry, that was a typo. 103db was the track limit. and 55db at the fence line if I remember correctly.

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13 minutes ago, Bill Strong said:

I am glad that I posted the actual rule in the BCCR so that Chris Huggins could read that and know that ChampCar is enforcing the 96db limit. Here, let me post it again.

 

 

Nothing wrong with posting the rule, but you must have good measurements to support your enforcement or you will certainly have trouble from members like me.

Sorry but that rule is just like many others with no real procedure to make a measurement. Once I see that outlined then I can either agree or not. Science HaHaHa, it is not funny if you send a team off that has done their best to meet the rule.

 

I do agree teams need to make a solid effort and it is not too hard to meet the numbers needed.

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15 hours ago, LuckyKid said:

Which side of the track will they be metering from for the tracks?

Our car is quieter with a side exhaust than it is with a spec miata exhaust, but it points directly at the sound station.   We use a muffler that is advertised as a moderate tone street muffler and we registered 101.2 before the silencer.  

 

Ditto with the direction it points really changing reading. 

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1 hour ago, MR2 Biohazard said:

I saw a team that had a sound violation on Friday, got told, put a baffle in it before their muffler, I helped weld it in and were fine with being below when they went out again. They had a muffler and a baffle. The track sound limit is 106db. For some reason during the race when measured again it was above the 96db limit. They got black flagged, cut up the tip some to try to fix it, but ended up changing the driving strategy to not hit the db meter there in that turn.

 

I wonder what happens here and why? The team did what they were supposed to do and tested and passed, then in the race got black flagged. As Bill says, they have a muffler, and with a baffle they had two. I am dumbfounded as to why this happened and why Champcar did not know about it to work with the team on a solution instead of potentially ruining their entire weekend. I think there should have been a better solution here and hopefully we can learn from it. Maybe have an official come down and talk with the team, have the team go up to race control and explain what was happening and what transpired before they basically ended the race for the team. It just does not sit well with me.

 

 

We had a team that had the same issues at Laguna Seca. The team was 100% certain we were wrong. They called me a few names too. Questioned my education. He was some sort of sound engineer. There was no way he was over the limit. After basically telling him he was on his last strike at Laguna, I questioned his exhaust flange joints as he had raised the car with a jack and rev'ed the engine. I isolated it to just after the header. It was an incomplete weld on a mismatched pipe adapter that allowed the sound to bypass the rest of the exhaust. Like hardly any exhaust pressure at the exhaust tip.

There are so many variables. 

 

The track took measurements at different locations with one main location track left. It's the same guy that does every event. It's his thing. 

ChampCar also does not like black flagging and keeping you from racing. We hate it. We really do. But there were also a vast majority of cars in the practice, and the race that had zero issues with sound.

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8 minutes ago, 55mini said:

Nothing wrong with posting the rule, but you must have good measurements to support your enforcement or you will certainly have trouble from members like me.

Sorry but that rule is just like many others with no real procedure to make a measurement. Once I see that outlined then I can either agree or not. Science HaHaHa, it is not funny if you send a team off that has done their best to meet the rule.

 

I do agree teams need to make a solid effort and it is not too hard to meet the numbers needed.

 

 

Thank you. And we try to work with them. It is hard when the majority of teams have no issue meeting the rule. Then we have a team or two that just can't because they made some racey side exhaust with a flow through silencer, with all sorts of custom mounting. I feel sorry for them. I do. I basically told him he would need to put a larger silencer on the car to get below the limit. His argument was that he would have to re-engineer his re-engineered exhaust. My only argument is that most of the other Miata had no issues meeting the sound requirements. The car that won the race was quiet too.

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54 minutes ago, Bill Strong said:

 

 

Thank you. And we try to work with them. It is hard when the majority of teams have no issue meeting the rule. Then we have a team or two that just can't because they made some racey side exhaust with a flow through silencer, with all sorts of custom mounting. I feel sorry for them. I do. I basically told him he would need to put a larger silencer on the car to get below the limit. His argument was that he would have to re-engineer his re-engineered exhaust. My only argument is that most of the other Miata had no issues meeting the sound requirements. The car that won the race was quiet too.

The car that won had a lower dB rating on your left hand station.  But it was not quieter than our car.  

You are not controlling sound, you are controlling for direction.  Since the track limit is 103(106?) this is a arbitrary CCES rule that is enforced in an arbitrary way.   Its my understanding that teams with exhaust exits on left side had the most issues (and tuttle).  Some were louder than others, but there were also ALOT of cars that were much louder but with rear exits.  

We have two exhausts, both street mufflers.  We ran the long (quieter one), welded in a silencer and turned down the pipe.  We asked the track for readings and were under the limit.  I had a conversation with you and you assured me I would not get black flagged, which stopped me from going to more extremes which would have included a trip to the autostore.   Its not like we weren't trying.   I even bought an extra 2.5" resonator off amazon before the race, but they sent a 3" and I didn't discover that until we were at the track.  

 

After the blackflag we riveted a bent piece of aluminum over the exhaust exit which we assume helped (we stopped short shifting then).  I don't think CCES was better off with us having a metal tire cutter mounted on the side of our car so that we knock off a couple dB.

You've been very helpful in offering advice and tips on how to help our situation, I was just shocked to get black flagged given the assurances we were given when it was known the effort we had made and the fact that our exit is directly at the sound station.  

An alternator terminal ended our chances that day, so the blackflag ended up being moot for us.  

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We run 2 mufflers on the old car and 1 on the new one (it’s getting the same 2nd muffler before RA).  Once we switched to 2 GOOD mufflers it was much friendlier on the senses and you could now hear all those fast cars coming up on you.  Also, because our car was quiet on Saturday morning Troy was actually able to hear the engine making a rod knock before it sent a rod through the block and oiled down the track.  Still needs an engine but saved the race from having a 30 minute FCY. 

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18 minutes ago, Ronh911 said:

 Still needs an engine but saved the race from having a 30 minute FCY. 

 

We in the trade like to call that "Quiet Time."

 

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For all those who are testing and sorting exhaust I might offer a thought that might help. In the past I was tasked with our local autocross club

to measure cars before the national's. Since we have a few fast guys and national champs in this group it was important to get them right.

 

Turning the exhaust tip down to the pavement helped in some cases but also amplified low frequency noise which is less offency then a whine of a rotary.

The best option found was to turn the tip or exit to the sky to allow it to dissipate in the air. I think I saw on the Reilly vette their side exhaust went up to the sky 

by the passenger door, might be wrong.

 

All side exits could have issues if that is the meter side. Both our cars are side exits but both have a turbo muffler and are fairly quite. I did a dyno test with one car with open down pipe and then with exhaust and we did loose 2-3 hp. Better to be in range of the rules then a couple hp.

 

Edited by 55mini
wording
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Reading this thread makes me want to weld a V-band to the tip of our car, and weld another to short bend that can be quickly installed and pointed in a direction to satisfy sound meters.

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