stujelly

So I was at thunder hill last week running with track masters. Anyway I got the meatball flag and when I came in they said I ran a 106.7 on their sound meter. I turned off sport mode and came back in a ran a 106.3 db.

I have the sharkwerks bypass but I can't believe they are that loud. Is that accurate?

Does that mean I have run the laguna set up now at thunder hill. The only problem is my car feels down on power with that set up.

Now what??

Suggestions?

Doublej

Sport mode will not change anything in terms of db level since the flaps open regardless of whether sport mode is on, they just open 1000rpm sooner in sport mode (3000rpm instead of 4000rpm)

I think I've hit 102 with SW bypass. Weather can play a part in your readings also...wind speed and direction for example.





JJ

Doc GTO

Maybe add some 90 degree bends on the tips (for track use only) and aim them opposite side of the sound booth. That helps at other tracks. Then, depending on which side of the track they record sound, you aim the other side!

LVDell

Makes me glad we don't have Db requirements out here at VIR.

P.J.S.

+1 for ORP

no way I pass sound at any sound restricted track... if a SW bypass is 103db, then I do not even want to hazard a guess where I am at

adrial

https://rennlist.com/forums/997-gt2-...2-seconds.html

gstahl

I have (had) sharkwerks bypass with a switch to control the exhaust valves on the 2010 GT3. Once I got popped for sound right at the limit (second lap of TT and last of the weekend so they gave me a pass). I have never run as high as 106 and never had a problem before or since. This is standard headers, cat, exhaust except for bypass and running with valves open all the time. 106 sound high but it is condition dependent.

drl

At Laguna don't they sometimes do "mobile" monitoring? Lil' bastards sneak around the track and you never know where they're going to get you?

NJ-GT

Stock 997.1 GT3 does 98 dB. With Sharky bypass pipes, it goes to 101db.

The 997.2 3.8 might be a little louder, but not much more louder, I would say 1 dB at most.

Weather, proximity to the track play a larger factor, and sound police have no idea of proper measurement. Overcast, fog increase the readings drastically. Measuring at 25ft and 50ft creates vastly different readings.

Running with valves closed can damage the engine by overheating the heads, and it will surely crack the side mufflers due to overheat.

Larry Cable

996FLT6

106 is like super cup exhaust territory. Damn that's loud. Was it foggy that day? Mike

savyboy

That is a fact not a speculation if you are running an Akrapovic. Side muffs on an Ak are not designed for WOT full flow. You'll damage an Ak by forcing valves shut. It happened to me and caused $5000k of damage.

Blocking exhaust flow builds heat and kills power. How is that good for fun or engines?

I don't miss LS or TH a bit after multiple encounters with the "Angels of Death" (sound guys) running in a stock car. Let's see...risk damaging my engine and exhaust system from the excessive backpressure, and my tires and body work from fallen off rigged crap from the back of cars just to appease sound ****'s? You can play that if you want to with your $100,000+ cars but I've had my fill.

Why would anyone support a track that does not support you?

Larry Cable

^ well said!

NJ-GT

I went into this same issue with Capristo. My idea was to keep the valves closed, so I could pass sound for SCCA events (now set at 100dB). My bone stock Fiat does 104dB.

The Capristo guys explained that containing the back pressure by having the valves closed would cause excessive back pressure at high RPM, overheat the engine heads, valves, headers, cats and mufflers. The end results are burned valves (requires a $$$ valve job), deformation on the aluminum heads (requires new heads), cracked headers, cracked mufflers and mounts. So I did not even try it.

This is the reason why my Scuderia even on the softest exhaust setting (rain mode), opens the valves at 3,200 RPM on WOT, 6,000 rpm at any throttle position, and varies from 3,200 rpm - 6,000 rpm depending on throttle position. The Porsche GT3 also opens the valves whether in Sport mode or not at 4,000 rpm.

The guys at Kreissieg (they make the best sound Scuderia exhaust), told me that their system could not be used at racetracks, it overheats and gets damaged.

The guys at Tubi Style told me their Titanium muffler cannot take racetrack use either, same for their Steel version. They have started making an inconel version that is track capable, but the other two systems overheating means they are not releasing enough back pressure. By taking a look at the systems that work the best in the Fiat, all of them bypass the muffler, so it is a straight shot from the cats and out.

Overheating the mufflers is bad, but that excessive heat is also going in the engine heades, valvetrain, headers, with more expensive consequences.

I'm now switching to a new system that offers similar back pressure to my stock system with the valves open, but it runs more quiet. The system has valve control which I'm going to wire to a dashboard switch, and with the valves open it produces very low back pressure (bad for mid-range, good for high RPM which is what I need for track days).

I Agree, I don't support tracks with sound police. They can vanish, I don't care about their history. There is common sense, Motorsports is a loud Sport whether it is with bikes, boats, snow mobiles, trucks or cars. People building houses around a racetrack complaining about sound have their place in Evolution per Darwin. People building racetracks in urban areas have their place in the Theory of Evolution as well.

Florida's Official Sport: Auto Racing. No sound Police. Racetracks in urban areas have great attendance, people love their racing here.

Lawn Mowers are louder in any neighborhood, and I haven't seen complains and regulations applied to these annoying devices. Airplanes are loud too, and I haven't seen airlines banned from International Airports.

drl

Seriously. Good point. Airplanes are not banned from approaching over surrounding neighborhoods, likely cause those folks don't have money to support such efforts. Not so in Monterey.

What are opinions of the mikymu mod in regard to what has been posted above? I have spoken with 3 mechanics from 3 reputable shops who suggest there should be no damage running this for an occasional event.