Paulyy

I know many race tracks have DB limits and well theres a road db limit for countries/states...

So if you've measured, how loud is your car (in db) & what exhaust system (pipe size, muffler brand/type & size, glass packs? resonators? catalytic converters?

thanks!

Willard Bridgham 3

Accurate sound meters are waaayyyyy expensive.

Van

With my turbo, I used to just pass Lime Rock's noise limit of 88 db with two pass through mufflers. One at the cat position and one at the muffler position. Pipe was 3" to first muffler, 3.5" to second muffler, 4" tail pipe.

Open pipe would not pass.

Paulyy

interesting, what size mufflers do you have?

reno808

I'll measure tonight

Paulyy

What you using to measure it with?

reno808

Iphone has a pretty good DB Meter app that matches well with track db meters

911-32

It depends how you measure it as much as anything else.

In the UK the basic test is static at 3/4 max revs, measured 1 metre from the exhaust at a 45 degree angle - and the max permitted is commonly 105db but some are 102db and some even lower. For reference, a std 3.2 911 will test at about 101-102db under these conditions at ~4500rpm. The front engine cars tend to test a lot lower on a static test as you would expect. Some tracks have drive by tests as well and those limits vary from track to track. Drive-bys are a "fairer" test that isn't biased against the rear engine cars but measurements depend on how wide the track is, what the line is, what gear cars are in, are there any walls etc.

Basically, you have to compare apples to apples, so what is tested at one track is only a rough guide.

The iphone meter is in my experience pretty good. We can also buy db meters for around GBP25 that are quite accurate and compare pretty well to what our tracks use. I have never had my 944 on the track, so I can't tell you much about actual experience for 944s. If you wanted to know about 911s on the other hand...

gruhsy

My i-phone reads 80 DB in the cab with windows down and sunroof open lugging along.

90-92 when I stomp on it...the phone is right by the gearshift.

Voith

Do you have any pictures of your complete setup? Sounds interesting. I think I will have to use two mufflers too since they are quite **** with sound levels here..

Zeff

I have no idea what my 951 does, it is loudish, but nothing compared to my old RX7. I had that car metered with one of the Radioshack db meters. 95db at idle and 128db on a flyby with the meter about 15 feet from the road.

alxdgr8

+1
I am going to guess that most standards are A-weighted also.
Sound/noise is what I do for a living, so it always bugs me when people ask how loud something is and expect a simple answer. It depends on a lot!

odb812

102 is the lowest limit I've had to comply with in the 951 and I had no problems with a 3" turbo back with SFR's quiettone muffler(2-chamber). I'd imagine most of us are below 92. It's really NA cars without mufflers that run into problems. The turbo effectively muffles a good bit of engine noise.

If you think you're going to be close, then find out where the limit is being measured and put a 90 degree elbow on your tailpipe pointed away from the side of the track where they measure. If you still have problems, upshift or lift when you pass the meter.

FRporscheman

So if the sound levels are measured from behind, intake mods and induction sound has much less bearing on the measurement? There's a guy that lives up the street from me who drives an Acura with a really loud intake. Every time I hear it I think it's something awesome coming, but it's just an Integra...

reno808

94-95 DB while warming up