Laguna Seca db Meter
 

I will be running Laguna Seca for the first time in a couple of weeks and am concerned about being too loud and getting black flagged. It's a long haul up there and an expensive weekend. I wonder if any of you with experience could tell me if my setup sounds like it will be a problem.
I have a 914-6 with a 2.7 twin plug, 11.5:1 CR, Webbers, stainless headers and SuperTrapps with 18 disks. The car is pretty loud, I set off alarm systems when I drive on the street. I know I can remove disks to quiet it down but I'm not sure that will be enough. I ran it with 6 disks once and it didn't seem that much quieter. Anyone have any advise?

My guess would be -- whether it's a 92 db or a 90 db day -- you are not going to pass with Supertrapps. On 90 db days, I've heard of factory exhaust setups getting black-flagged.

But hopefully someone here with your exhaust will sound in.

quieter is not good enough, Jack is right, silent is basically what you need, I am running this for laguna

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are you coming to this event? if so 92Db is the limit, and that is still very quiet

Jim

90-92 db?

Whats up with THAT? You can't run a moped at 90db!

That's just wrong on soooo many levels...

I heard the sound hurts the ears of a rare species of bird which inhibits them during mating season and it is effecting the population....or something like that.....http://www.pelicanparts.com/support/.../FFflower2.gif


note that ehaust system is 1.5 inch tubing, so it really restricts the flow and the sound, so plan on doing everything you can, and if possible vent the sound out to the drivers side, the sound booth in on the passangerside going up the hill to turn 6

Yeah, my old Flowmaster would pass 92 but fail 90. It was on par with a stock 993, in terms of noise. On 90 db days, I would have to let up on the hill to 6, which costs time.

Like Jim says, L-shaped tubes pointing to the driver's side will help. But I don't know that I've ever seen anyone running supertrapps at Laguna.

Why is there a sound limit? Well, Laguna Seca is a facility with a unique history. "The track's been in existence since 1957, and since that time non-profit association SCRAMP (the Sports Car Racing Association of the Monterey Peninsula) has been responsible for maintaining the track. Laguna Seca was a part of the Fort Ord military base until 1974, when it was handed over to the County of Monterey. From the year of its founding up through 1985, the track was only 1.9 miles long. In 1986 the track was lengthened to to 2.21 miles, and a decade later in 1996 became 2.23 miles."

The problem is, it's not privately run, so it's got to make the locals happy (in spite of the fact that SCRAMP "has utilized the raceway as a means to benefit local charitable and non-profit organizations while promoting economic vitality of the surrounding area, distributing almost $10 million to some 90 Monterey Peninsula charitable and service groups over four decades. SCRAMP and Laguna Seca have established themselves as the most important economic and charitable organization in Monterey County.")

Thanks for the advise guys, although it's got me kind of depressed. I was really looking forward to running Laguna Seca but I'm not going to waste that much money and get black flagged. I have a pair of MagnaFlow mufflers like they use on V8's but again the car isn't much quieter with them on either.

Just out of curiousity, what do the vintage racers do that run at the Monterey Historics? Hard to believe that they quiet those cars down that much.

The track gets a certain number of 'free pass' days per year. They don't waste those on our DE's

In my last DE at Laguna, I only saw 1 vehicle get black-flagged for noise, and that was a newer Corvette that had pretty much straight pipes coming out the back. Lots or interesting muffler add-ons were run for that event, with all kinds of plumbing directing the exhaust tone to the car's left, away from the sound booth. And then there are always the rebels...

Tom
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It isnt just the Exhuast that makes noise its intake noises too, The Earlier Engines with the thinner cooling fins always have the most trouble passing sound at Laguna. The GGR event there is always fun Becuase of all the Expressos looking contraptions that show up . Im Glad my car passes at 83 db

The top ends of the pipes look like they are covered. Are you sure they aren't acting like a bass trap, collecting sound from the intake and muffleing it?

On the carb'ed 914 in particular, you also need to pay attention to the intake side as well as the exhaust. You'd want to run a stock engine lid (if you have a GT mesh type) and also a stock "closed" airbox. I know my car has ITG foam filters with a GT lid, and the Webers seem louder than the Dansk 2-out sport muffler. Only with open megaphones can I even hear the exhaust above the induction sound.

I think a 914-6 or early 911 would have great difficulty making 90-92dBA even with a stock induction & exhaust. In original factory form, the cars are already surprisingly loud compared to modern water pumpers.

It's a true shame as I would love to drive Laguna one day but it would probably have to be in a rented Ford Focus or the like!

We have a strict 92db @ 50' policy at Qualcomm and I have never seen an early 911 or 914 with stock induction and exhaust fail sound checks. Sport exhaust and "open element" induction systems are on the edge-- some days they make it, others they don't. It depends on atmospheric conditions and meter position, etc. So far, I have always been able to pass with my early 911 w/ a 3.4 and PMO 50s w/ K&Ns and rainshields, if I run the JWE/Pete Weber Phase 9 headers with the cross-chamber silencer on the car. It is much louder than a stock muffler, but still under 92db.

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It's a true shame as I would love to drive Laguna one day but it would probably have to be in a rented Ford Focus or the like!

Don't give up on driving your Porsche there. Get a day w/ a 92db limit and you can make it pass. The key issue is to ask for a sound check in your first session. If you ask for a measurement, they will give you a chance to modify your car and try again. Some of the tricks mentioned here should be enough to get you thru if you fail the first time, but most importantly, you won't get thrown out and lose your entry fee!

TT

"Don't give up on driving your Porsche there. Get a day w/ a 92db limit and you can make it pass. The key issue is to ask for a sound check in your first session. If you ask for a measurement, they will give you a chance to modify your car and try again. Some of the tricks mentioned here should be enough to get you thru if you fail the first time, but most importantly, you won't get thrown out and lose your entry fee! "

So that I understand, if you ask for a measurement they let you make adjustments. If you don't they don't let you back on the track even if you make changes? I'm having different mufflers installed but am still a little paranoid about wasting my weekend.

Yeah, but you're also not going WFO uphill on a straightaway in 3rd or 4th gear. Those conditions push an engine as hard as it can be pushed, which makes it develop max hp.

Not sure what you mean by this. Max hp = max noise? OK. I'll buy that. But WOT at redline in any gear is the same. I have been at the top of 3rd gear in the parking lot at Qualcomm many times, and there is more elevation change there than you might expect. Not as much as Laguna Seca, but the sound shack is also farther away than 50' there.

I had no problem passing 92 db sound limits at Laguna Seca even running flat out up the hill from 5 to 6.

TT