Thunderhill, Noise limit of 103 dB Options

[slivel]

Has anyone run at Thunderhill who can comment on the noise limit of 103 dB. I have run at Laguna Seca at 93 dB limit and had to use mufflers to comply. Does 103 dB allow enough for an open exhaust?
Steve

[race914]

With my 4 I run a Phase 9 and Supertrapp at Laguna to meet the 93db. I got a sound reading at the SCCA Vintage with just the Phase 9 at 95db.

I don't think I'd even be close to 103db if I removed the Phase 9...

A few years ago at Laguna a 962 went above 103db but it was from the turbo, not the exhaust.

Another point of reference. A 914-6 ran headers straight to megaphones at Thunderhill and was not called in. It was loud however (could hear it all the way around the track from the pits) and I wouldn't recommend that.

[drew365]

My car is pretty loud with SuperTrapps and I had no problem at T-Hill. At the last POC event I was at, only one car got black flagged for sound. I think that Laguna is much more strict about enforcing.

[race914]

(IMG:http://www.914world.com/bbs2/html/emoticons/agree.gif)

Laguna has the roving sound meters so you can't just 'lift' at the sound station and expect to be ok...

TH isn't quite as bad (yet)


Funny story.

I did take the Supertrapp off at Laguna when I ran with the 'big bore' group which has the 103db limit.

I was in my pit next to a 66 Shelby GT-350 and couldn't even hear my car when he pulled up.

He even asked me "is that thing running?" He was joking though. He wasn't laughing as hard after our first run session. A new found respect for hp/weight v.s. just hp!

[drew365]

QUOTE (race914 @ Apr 7 2006, 07:43 AM)

I was in my pit next to a 66 Shelby GT-350 and couldn't even hear my car when he pulled up. He even asked me "is that thing running?" He was joking though. He wasn't laughing as hard after our first run session. A new found respect for hp/weight v.s. just hp!

I need to get out more! I only run with the POC and the taildraggers in my class are pretty tough to beat. I'd like to embarass a few pony cars. (IMG:http://www.914world.com/bbs2/html/emoticons/biggrin.gif)

[Trekkor]

I've been on track four times at Thill now.
I've not seen a single car get flagged for sound.

They mention the 103db during the driver's meeting.
103 is really loud compared to 92.
I run at 87.

The only time sound was enforced when I was there was during the 25 hour race that I watched.


KT

[Trekkor]

QUOTE

TH isn't quite as bad (yet)

Both Sears and Laguna were once in the middle of nowhere.
People start building closer and closer and then they complain louder and louder.

Many people would like to see the tracks close if they have it their way.

Thill is still out in the sticks.



KT

[nine14cats]

Hi Steve,

At THill with your 3.4 you should make it under the 103 no problem. I ran our 914-6 with Webers, headers and phase 9's and made it. At Laguna the carb induction noise was the big problem and I had to lift at the sound station, even with a banana muffler. I didn't get caught by the roving meter lady!

Our new car with a 3.6, FI and phase 9's is a tad quieter than the high strung 2.7 we had before.

What muffler system are you running?

Bill P.

[DanT]

After a little over 2 years working as the GGR Time trial track co-steward, working at the head of grid as well as in the tower, I have never been requested by the TH officials to black flag any of our cars for sound...period.
Never had any discussion on the headsets with any of the corner workers about any of our cars being too loud, or needing to be black flagged for sound.
At least with GGR there just has been no sound problems.

I think at TH most of the time they just make a suggestion of 103 and asume that most will adhere to it.

With our TT series we have cars running headers into megaphones at TH with no issues....not that that combination isn't loud

(IMG:http://www.914world.com/bbs2/html/emoticons/biggrin.gif)

[slivel]

QUOTE (Dan (Almaden Valley) @ Apr 7 2006, 08:43 AM)

After a little over 2 years working as the GGR Time trial track co-steward, working at the head of grid as well as in the tower, I have never been requested by the TH officials to black flag any of our cars for sound...period. Never had any discussion on the headsets with any of the corner workers about any of our cars being too loud, or needing to be black flagged for sound. At least with GGR there just has been no sound problems. I think at TH most of the time they just make a suggestion of 103 and asume that most will adhere to it. With our TT series we have cars running headers into megaphones at TH with no issues....not that that combination isn't loud (IMG:http://www.914world.com/bbs2/html/emoticons/biggrin.gif)

So you think that I can get away with open exhaust (megaphones)? I attached a photo of the mufflers that I have but would rather not install them if I can get away with open exhaust. When I last ran at Laguna Seca I had to layer foam around the carbs to muffle the intake noise to pass L/S 93 dB.

Steve

[DanT]

It is always hard to tell for sure. Depends on what group you are running with. They may not like the sound even though you do.

I would try the megaphones but possibly take the mufflers with you in case you need them. If you cant get the mufflers there, then I would install them...you would hate to go all the way there to be sent home due to sound. (IMG:http://www.914world.com/bbs2/html/emoticons/wink.gif)

[slivel]

QUOTE (Dan (Almaden Valley) @ Apr 7 2006, 02:52 PM)

It is always hard to tell for sure. Depends on what group you are running with. They may not like the sound even though you do. I would try the megaphones but possibly take the mufflers with you in case you need them. If you cant get the mufflers there, then I would install them...you would hate to go all the way there to be sent home due to sound. (IMG:http://www.914world.com/bbs2/html/emoticons/wink.gif)

Room is not a problem - I have an enclosed trailer. Guess that I will start out with the megaphones as you suggested and put the mufflers on if I get busted for sound. I'm running with HSR West. Last event at Willow I was in the big bore group with the Shelby Mustangs, Sunbeam Tiger, Corvettes etc. There was even a Rondeau in my group - what a car!!!! BTW, I was faster than all of the big bores except the Rondeau.

Another question about T-hill. My gearbox is AFMSX, am I going to be top end limited. At CMS I am at redline in 5th all the way around the oval portion. The ratios are great for Willow and Las Vegas though.

[DanT]

Depending on which direction they run the track in you may be out of RPMs on the main straight. The rest should be ok.

TH is a very wide open track for the most part. There are several areas the you will be up in the gears. turns 6-8, 9-10 (down the hill) , back straight and main straight. If you run CW then you most definitely will be RPM limited on the main straight.
In my 2.7RS 914-6 in CW direction I would redline in 5th before the braking zone on the main straight. Yes, I had a short 5th gear.

[slivel]

QUOTE (Dan (Almaden Valley) @ Apr 7 2006, 03:08 PM)

Depending on which direction they run the track in you may be out of RPMs on the main straight. The rest should be ok. TH is a very wide open track for the most part. There are several areas the you will be up in the gears. turns 6-8, 9-10 (down the hill) , back straight and main straight. If you run CW then you most definitely will be RPM limited on the main straight. In my 2.7RS 914-6 in CW direction I would redline in 5th before the braking zone on the main straight. Yes, I had a short 5th gear.

Dan, thanks for the info. My rear tires are 25.6 inches in diameter (275/45/16) for comparison to your car.

Guess I'll roll the dice and start out with these:

[Trekkor]

QUOTE

My gearbox is AFMSX

Mine, too (IMG:http://www.914world.com/bbs2/html/emoticons/boldblue.gif)

I have yet to run out of 5th gear.
( but I'm slow, and have only run ccw direction, so nevermind ).

CCW is considered "normal" at Thill.

When is your track day?


KT