Decibel Readings on my Side Pipes

[patrickt]

I usually put my car away around now and then pull her out in the spring. Since I picked up a new Windows Surface to play with, one of the free apps that you can download for it is a decibel meter. So, I thought for the last Cobra task of the year I'd check my side pipe loudness. Now these are "quiet type" pipes from ERA and sound very nice (clicking the link below lets you hear them). They don't hurt my ears like some FE Cobra's do. At idle, about a foot away from the pipes, the reading never went above 95. Here's a pic:

[kevins2]

Hi Patrick,

I went back and forth over the sidepipe issue and wound up ordering the quiet pipes. My Harley is loud and at first I loved it - makes the testosterone level peak. But...it got old after a while, so I installed quieter baffles. If your app is accurate, that's perfect.

Happy Thanksgiving.

Kevin

[Don]

Did a search on the Apple iPhone App Store for " decibel meter ", returned 73 apps, free and charge, a variety of displays and features.

[ERA Chas]

OK now test outdoors, 5' away and 20' away at 90 degrees to the side of the car. Test at idle and 3000 RPM.
Post here.
Oh wait-it will go 3000 RPM right??

[patrickt]

Originally Posted by ERA Chas

OK now test outdoors, 5' away and 20' away at 90 degrees to the side of the car. Test at idle and 3000 RPM.
Post here.
Oh wait-it will go 3000 RPM right??

Well, that was outside. And pretty much in the open too, so there was nothing to bounce off of. But I really don't know how accurate that little app is. The "Help" file says 95 is the equivalent to thunder, but I really don't think my pipes are that loud. But, then again, I've never put my ear a foot away from the pipe openings while it was idling. Maybe in the spring I'll do it again for you, but for now, she's gone to take her beauty sleep until Easter.

[ERA Chas]

Originally Posted by patrickt

...she's gone to take her beauty sleep until Easter.

OK so that means you'll give your post count a break and re-join us in the spring??

[patrickt]

Originally Posted by ERA Chas

OK so that means you'll give your post count a break and re-join us in the spring??

Uhhh, now would RGIII take a break like that?

[vatdevil]

Using an IPad app, 91 db idle at 1 ft. Small block with 3 inch pipes.

[patrickt]

Originally Posted by vatdevil

Using an IPad app, 91 db idle at 1 ft.

Using the 64Gig Surface is an absolute delight for surfing, reading books, and basic monkeying. However, it is absolutely abysmal for email with the only email app that is available for IMAP and POP3. These are the ARM processor Surfaces, the Intel processor Surfaces come out in January and will support all the regular Windows apps that you now run as well as Win8 stuff. Unless you make it a habit of just buying electronic gizmos when they come out, and then parking them in the corner a month or so later, hold your money until January.

[dcdoug]

Originally Posted by ERA Chas

Oh wait-it will go 3000 RPM right??

His engine builder told him it would.

[dcdoug]

Originally Posted by patrickt

Maybe in the spring I'll do it again for you, but for now, she's gone to take her beauty sleep until Easter.

Wait, it's 60 and sunny for the next three days and you put it away?

[madmaxx]

Sound is tricky. A popping a sound can be 90db or a deep throat rumble. When it comes to side pipes you really have to hear them side by side

[patrickt]

Originally Posted by dcdoug

Wait, it's 60 and sunny for the next three days and you put it away?

I took her out yesterday for the final run of the season and it was a bit chilly for me. It's 53 degrees as I'm typing this, and at the end of the driving season that's just too low. Now, at the beginning of the driving season mid-50's is OK. It may sound funny, but putting her away for five or six months each year really makes it more fun to drive. It's like getting a new toy every spring.

[patrickt]

Originally Posted by madmaxx

Sound is tricky. A popping a sound can be 90db or a deep throat rumble. When it comes to side pipes you really have to hear them side by side

You're right. I was able to snap my fingers a time or two and hit 94db with the Surface just sitting on my lap.

[rodneym]

Patrick,

What kind of weighting does that app have and which did you use?

[patrickt]

Originally Posted by rodneym

Patrick,

What kind of weighting does that app have and which did you use?

This is it: Decibel Meter app for Windows in the Windows Store

[itstock]

78.4 same position as you had it through my EVO phone (outside), sbf through the stock backdraft pipes. Idle is right below 900rpms. 95db is LOUD. Oh, and 38* is too cold for driving this damn car (and I have heated seats)!

ETA: I tried it on the Ipad in the garage, same thing. Initial startup is 91, but idle is roughly 78.

[madmaxx]

Patrickt,

I am shocked, have you turned over a new leaf? I thought you were into authencity. What is the deal with the surface? If you want the real thing, get an iPad! I am down $40k on my apple stock in last month, I have to try everything to get sales up.

[patrickt]

Originally Posted by madmaxx

Patrickt,

I am shocked, have you turned over a new leaf? I thought you were into authencity. What is the deal with the surface? If you want the real thing, get an iPad! I am down $40k on my apple stock in last month, I have to try everything to get sales up.

IF the WinPro8 Version with the Intel Processor, that comes out in January, runs as fast as this ARM processor model does, and if it works as well as this limited ARM model does, and IF it does indeed run legacy Windows apps without crashing, and IF it supports peripheral devices without rolling over and playing dead, it will be a killer, must-have combination. BUT, every year I buy these little notebook jobbies that run Windows, and each year they improve, but they've never been ready for prime time, much less be able to run anything that's processor or graphics intensive. Maybe January will be different....

[Mohuska]

Gentlemen,

I regularly conduct acoustical measurements throughout industry and design acoustical dampening controls and want to point out somethings about your measurements.

We have used professional calibrated noise measurement instruments and compared against a number of iPhone/ipad or android apps and found the computer apps in general to be between 8 and 33% off. Most of these apps read high by about 12-16%.

It also matters where you measure as sound pressure will decrease by 1/2 with a doubling of the distance.

It also matters that your app scale is A weighted. This scale most closely represents the human ear. If you are reading C scale or unweighted, you will be substantially off from the true readings.

Finally, increased rpm will increase sound pressure level up through about 5500 rpm. After that, not a whole lot.