foko

Hi all.....
I was running at Laguna Seca today and was black flagged for noise.
They have a 90db limit....with a check station on the uphill straight between turn 5 and 6.

The rest of the day I had to just cruise that straight to avoid getting thrown out. Plus, they claim that on some days, they move the sound check around so that "lifting" won't save you.

I run a single turbo fd with,racing beat cat back and borla race muffler in the mid pipe. That ain't enough. The borla really quieted down cruising and idle noise, but doesn't do much for WOT

Would a high flow cat be more quiet? How about a "turndown"? Any other options?

I'm going back in 10 days and need a solution quick.

TIA
Fabian

Silkworm

Turndown at minimum, but probably more like a different muffler combination.. Also look at intake noise, that can be almost as loud as the exhaust.. Most of the race RX-7s have trouble at Laguna..

Did they say how much over you were?

PaulC

HWO

get a clamp on 90 degree bend on the end of your exhuast, turn it in the opposite direction from where the noise metering device is - thats what all the 2 litre super touring car teams in the UK do. it works too

Bake

Bummer............what group are you running with?

I've been wanting to run at Laguna for some time.
I am getting tired of Thunderhill.

Thanks,
Bake

tims

look to the intake side. I think the exhaust is fine with the addition of a turn down pointed down and to the center of the car. last time I was there the turbo cars were having problems with wastegate and BOV noise. a guy with the same setup you seem to have had a problem with the BOV because the sound meter was located close to an upshift point for him. you may need to muffle the intake and the BOV to keep the noise down. Also one of the turbo Porsche's was having problems with the wastegate chirping setting of the meter. just don't concentrate on the exhaust as the intake noise can also set you over the limit, as happens to some of the big bore V8 cars. that 90db is street car quiet or sometimes quieter so be sure you have it covered. good luck

foko

interesting thoughts. from inside the car it certainly seems to be all exhaust noise. however, i realize that what the db meter "hears" may be a combination of all the noise from the car.

having said that, how does one quiet the intake without adversely affecting flow? i've seen and heard BOV's with all sorts of mufflers on them and they sounded different, but still loud. does anyone have a specific recommendation on that?

my wastegate is already plumbed into the downpipe, not sure what else to do there.

thanks for the thoughts, keep em coming.

fabian

1FooknTiteFD

Foko, your best best is to switch back to your stock cat back next time you go to Laguna seca. I know it sucks, but that's just about hte only thing you can do. I know someone who has a straight piped FD (with no borla) and he didn't get flagged if he puts back his stock exhaust.

It's kinda stupid how they have noise regulations at laguna seca because of the stupid people living nearby the track complaining about the sound. That's like moving near an airport and telling some airplanes not to take off because it's too loud.

tims

all the things you mentioned will adversely effect HP but this happens to everyone so don't be to concerned about a little less power. routing the BOV into the intake and adding some type of enclosure to the air filter will help.

mbviper

use a turn down with an adjustable fitting so that you could direct the sound down and away from the meter.
i had the same problem at a scca event and cut nearly
10 dbs off with this and never had to lift again.

DomFD3S

http://vca1.viperclub.org/ubb/Forum14/HTML/014566.html

foko

Here's and update:
With a Borla XR1 race muffler in the midpipe and a MazdaComp muffler at the back, the noise level was still 94.8 db at WOT going up the hill between 5 and 6 at Laguna Seca.

The final fix was the turnaway.....ugly but effective.

Thanks for all the replies.

foko

Here's and update:
With a Borla XR1 race muffler in the midpipe and a MazdaComp muffler at the back, the noise level was still 94.8 db at WOT going up the hill between 5 and 6 at Laguna Seca.

The final fix was the turnaway.....ugly but effective.

Thanks for all the replies.

Samps

I can't believe they have not ruled against the use of such a thing yet. Does it actually direct the noise away from the people who are complaining about the noise or is it just pointing it away from the meter? I guess if it makes the grumpy locals happy then why not!

maxpesce

Use a TURN DOWN pointed away from the meter & down 45deg, insted of straight out to the side. Aimed down like that is better b/k the Asphalt of the track will absorb a lot of the sound energy. If they place the Sound Meter opposite a Conc. Wall (like they do a lot at LAGUNA) then just turning the exhaust to the opposite SIDE won't help much b/k the sound will just reflect off the Conc. and back to the meter.

Silkworm

Samps,

At laguna, yeah, the sound meter sits at the closest point to the houses that are bitching, so the turndown gets the noise pointed away from them.. The houses are well over a mile away, don't get us started on the whiners in Monterey.

PaulC

Samps

I bet if you strapped ol' granny into a race prepped 7 and took her around the track a few times she might forget about the noise.

And how bad will an exhaust tip like that hurt performance? In the past I thought about using a turn down on the steet just to quiet down the noise but was told it would make no noticable difference. Are we talking about noise levels that cannot be determined by the human ear?

Silkworm

Well, a turn down doesn't really hurt performance much, it just directs the sound at a different angle. So overall, the sound doesn't change volume, it just is focused away from the microphone measuring the sound levels.

Now, I'm looking at having to add a supertrapp and a 90* turndown to my car to run laguna, the supertrapp is going to significantly affect powerlevels, but it's easier than trying to splice into the exhaust to add another muffler inline when I don't need it for the other tracks I run here.. Laguna is a great track, but NASA almost never runs there anymore.

PaulC

foko

Not sure if the turn "away"should be a turn "down "instead. I was told by several to point it up and left, and others said down and left. I've seen both at Laguna. I assumed the asphalt would reflect rather than absorb the exhaust noise, however, thats just my speculation. Any acoustic engineers out there? The track officials claim that the sound check is moved around, but no one I asked could ever remember the sound check anywhere but at the rise between 5 and 6 on the right side of the track.

Having said all that, Laguna is a great track and my opinion is that its worth the trouble to run there. Not much point in complaining about it at this point....just got to work around it.

Good Luck
Fabian

maxcooper

I thought we had some funny setups at WWW, but those Porsche systems are a riot! Someone should go around and black flag lawn mowers in that area.

-Max

Ni5mo180SX

I think some of the sound waves would be absorbed by the asphalt with the majority reflecting off depending on the angle it hits the asphalt. Have you seen the exhaust used on RE Amemiya's FC2000, turns down towards the ground at the tip.