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

 

Put a seperate muffler on the WG, or plumb it back into the DP.

 

I didn't get that he was running an open wastegate.

I am interested in the answer to this problem since I would like to go to Laguna Seca for a track day next year.

 

Cheap solution might be to install an orifice somewhere in the exhaust between a couple of flanges. Won't help performance but it may cut out some noise.

 

I've been black flagged with the stock turbos there several times. The WWW events were full of interesting devices designed to get past the sound police. The nicest setup was the "Laguna Pipes", which consisted of two upturned pipes that bolted over the back of the RB dual-tip cat-back to direct the sound away from the sound meter side of the track. From there, it quickly went downhill. Tin cans, dryer vents (nice for roasting license plates), etc. all were seen on the backs of cars. Some even fell off or just plain didn't work. I just resorted to driving slow by the sound booth.

You might try something like the Laguna Pipes setup. I think that getting the downpipe ceramic coated and wrapped might help keep the sound levels down, too. My RX6 downpipe is very thin, and I can't help but think that increasing its weight would quiet the car down.

You might try selling your current midpipe and making a new one with a Borla ProXS muffler. They flowed about the same (on a 370 RWHP NA Mustang) as the XR-1 but it was a good bit quieter. One of the Mustang magazines did a big muffler test recently and they all flowed very similarly, but there was a big difference in noise. I don't think they have a 3" center/center ProXS, but I think I did see a 3" center/offset one that would probably work.

-Max

 

The cheapest and easiest way to tackle this problem is to take off your midpipe, and weld a plate (much like a throttle plate at WOT) inside the exhaust pipe. Splitting the exhaust stream should really quiet it down.

Fred

 

wastegate is already plumbed into the downpipe. a restrictor is not an option.

the "throttle plate" concept i've never heard of. how long does this plate have to be? seems like it would be difficult to run it the length of the midpipe.

i'll have to look into that other borla muffler though, that may be the most satisfactory solution.

are there any downsides to wrapping the downpipe with insulation? the obvious upside is lower underhood temps and maybe some sound insulation.

i'm gonna try the laguna pipes too. actually one spec miata there was also black flagged for noise and subsequently appeared with laguna pipes. i suspect it worked enough for him since he continued to run all day.....although i'm not sure if he was lifting at the sound booth after the pipes went on.

thanks for the thoughts.....keep em coming.

fabian

 

Why are there noise limits at a race track? I'm sure they dont impose them on F1 cars when they race there.

 

F1 cars race Seca?


Oh yeah they do historics...


They usually have noise restrictions on "sportsman" days, not crowd drawing events / pro race series.

I cant imagine theres any restrictions at Pomona during NHRA weekend, yet you go there other days and you get booted for farting too loud..

 

Because the dumbasses who have houses there complain about the noise coming from the cars near the racetrack. So stupid. It's like moving near an airport and complaining about the sounds of planes taking off.

By the way, where can I get a set of Laguna pipes? Anyone have any pictures? I'm planning to head to laguna for a trackday myself sometime in the near future, and it would really suck if I had to slow down...

 

The exhaust splitter doesn't have to be long at all, just a couple of inches long would work. Get a piece of steel that's 1/8" thick, 3" long, and 2" wide, I think that'll be fine. Try that and if it doesn't work, it's easy to take off. But if should work wonders, in theory.

Fred

 

somehow being quiet at a race track makes no sense to me. Soon we'll have to pass emissions too.

 

I second that...

 

i would run a flow master race series muffler where the main cat used to be. I has chambers and really helps. i run it in my race car. its about 94db with a straight through 12'' dynomax at the back

 

Could you explain the theory?

 

baffling of the exhaust stream is nothing new, lot of motorcycle/marine/sandrail racers have tried it, in fact even the NA FC rx7's have them in the exhaust sleeves. It works by resonate/alter the frequency of the exhaust.

here's a good product to try and will be even better than the solution I proposed earlier (even though it'll cost at least $100 more, I really think this will solve the problem):

http://www.mccordcg.com/mpp/mpp.htm

Also check out the testing results of the Powertip Silencer (mainly just a tip with a baffle and some proforation) here:

http://www.cpperformance.com/Dealers...xhaust/023.asp

 

As far as wrapping your downpipe, I've heard reports that it caused the heat to build so excessively that the downpipe actually melted. I can't verify that, but the source was a guy that's been racing rotaries for at least 10 years, and he's not the type to make something up. Something to consider.....

 

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

Check this thread out for some help.