07-09-2016, 07:23 AM
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#1
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Registered User
Join Date: Apr 2016
Location: Norway
Posts: 29
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Circuit werks exhaust. Resonance. Decided to DIY PSE
Hi.
I bought and installed the circuit werks exhaust from ebay.
The exhaust is fine over 3000 rpm but has wery loud resonance under 3000 rpm. Just the smalest step on the pedal and it's unberable.
Does anyone else have som experience with this exhaust or solutions to fix the resonance?
If not, I wil go back to stock or look for the PSE witch i think wil be a more comfortable balance betwen cruising and good sound over 3000 rpm
Carl
Last edited by RedBeauty; 07-12-2016 at 09:40 AM.
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07-09-2016, 08:07 AM
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#2
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Certified Boxster Addict
Join Date: Nov 2010
Location: Los Angeles
Posts: 7,669
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That is the same exhaust as the Top Speed and it is fairly common to get drone at 3K rpm.
Do a search on "Top Speed exhaust drone" (and/or similar terms) and you can read what others have done to fix it. I am sure that a lot of folks will jump in on this thread shortly...
__________________
1999 996 C2 - sold - bought back - sold for more
1997 Spec Boxster BSR #254
1979 911 SC
POC Licensed DE/TT Instructor
Last edited by thstone; 07-09-2016 at 08:11 AM.
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07-09-2016, 09:14 AM
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#3
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Registered User
Join Date: Apr 2016
Location: Norway
Posts: 29
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Thanks for answer. I dont have anny drone. Only deep rumbeling bass. Low frequense
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07-09-2016, 09:42 AM
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#4
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Certified Boxster Addict
Join Date: Nov 2010
Location: Los Angeles
Posts: 7,669
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Check it for exhaust leaks.
__________________
1999 996 C2 - sold - bought back - sold for more
1997 Spec Boxster BSR #254
1979 911 SC
POC Licensed DE/TT Instructor
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07-09-2016, 09:57 AM
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#5
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Registered User
Join Date: Oct 2015
Location: Austin
Posts: 395
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I believe that 2k - 3k resonance is what we call drone and it is annoying, I had 3 different exhausts and only one semi-drone-free is stock
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07-09-2016, 10:25 AM
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#6
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Registered User
Join Date: Apr 2016
Location: Norway
Posts: 29
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There is no leaks from the exhaust.
I've might missunderstood what drone is. I belived that was a more high frequent sound.
Unles there is a easy solution to fix this i wil put the Stock back on as i use the car evry day. too bad since the sound over 3k was Nice
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07-09-2016, 10:43 AM
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#7
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Registered User
Join Date: Nov 2015
Location: ontario
Posts: 377
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Many people have had the same issue with that exhaust and reported that it went away with the addition of secondary cat bypass pipes. However, if you have an earlier car (2.5L) that only has two cats this will give you a check engine light.
I have the bypass pipes right now and ordered that same exhaust based on the good reviews I have read about the combination.
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07-09-2016, 11:17 AM
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#8
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Registered User
Join Date: Apr 2016
Location: Norway
Posts: 29
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I have the 1999 2.5L, so i cant remove the cats
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07-10-2016, 08:22 AM
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#9
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Registered User
Join Date: Oct 2015
Location: Pittsburgh
Posts: 99
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Give it time to coke up, I put the circuit works exhaust on mine, but also had the cat bypass pipes and c pipes too, drone was very loud for the first few hundred miles, but, it will get better with use.
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07-10-2016, 03:48 PM
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#10
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Certified Boxster Addict
Join Date: Nov 2010
Location: Los Angeles
Posts: 7,669
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Quote:
Originally Posted by Carl.O
There is no leaks from the exhaust.
I've might missunderstood what drone is. I belived that was a more high frequent sound.
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Drone is a when the exhaust exhibits a particularly louder sound at an annoying frequency in a fairly narrow rpm range.
The Top Speed/Circuit Werks/etc cat back exhaust is pretty well known to exhibit this behavior around 3000 rpm and it is typically heard while cruising on the freeway at near constant speed/rpm. The constant din of extra loudness/unique frequency can be fairly annoying.
Let us know if this is what you're experiencing or if its something different.
__________________
1999 996 C2 - sold - bought back - sold for more
1997 Spec Boxster BSR #254
1979 911 SC
POC Licensed DE/TT Instructor
Last edited by thstone; 07-10-2016 at 03:51 PM.
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07-10-2016, 04:48 PM
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#11
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Registered User
Join Date: Dec 2014
Location: Pacific Grove, CA
Posts: 494
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Quote:
Originally Posted by Carl.O
There is no leaks from the exhaust.
I've might missunderstood what drone is. I belived that was a more high frequent sound.
Unles there is a easy solution to fix this i wil put the Stock back on as i use the car evry day. too bad since the sound over 3k was Nice
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"Drone" is caused by exhaust valve harmonics. The thinner the metal on the headers the louder the drone. It's why your stock headers are so bulky and thick they help mask the drone and it happens the loudest in exactly the rpm range you are stating.
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07-10-2016, 06:51 PM
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#12
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Registered User
Join Date: Sep 2013
Location: Chandler, AZ
Posts: 1,796
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A number of other forum members have noted that installing the secondary cat delete eliminates the drone issue. Hopefully someone that has done this can chime in a validate.
__________________
03 Carrera
02 Boxster S Guards Red, black interior with matching hardtop
89 Carrera 4
89 944 S2
78 911SC
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07-10-2016, 07:00 PM
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#13
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Registered User
Join Date: Dec 2012
Location: FL
Posts: 4,144
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I just installed a Beluga racing exhaust on my 2000S today, (it looks exactly like the top speed/manzo/ebay ones) and I have top speed 2nd cat delete pipes already. First run, fart can city and terrible drone around 2500-3000 rpm. Chatted with Barchetta (thanks!) and went back underneath tightened/checked my connections, and low and behold I was able to get a little bit of turns on several fasteners. No more fart can and no drone. Louder than stock, nice deep rumbly sound especially when you get on the gas. I took a video but can't check it until Tuesday to see if it picked up the sound, will post it up if it came out good. Edit: I am using the 2" easyseal wrap style clamps to connect the Cat delete pipes to the short pipe that connects to the U pipe that goes to the muffler. Using the stock clamps on both ends of the U pipe.
Last edited by steved0x; 07-13-2016 at 07:58 AM.
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07-11-2016, 09:07 AM
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#14
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Registered User
Join Date: Jul 2004
Location: Houston, Texas
Posts: 7,243
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Another forum member with the same muffler (Top Speed) put a motorcycle baffle in one side of the muffler inlet and it changed the harmonics and solved the drone issue.
You might try this as it's cheap and worth a try. I have the same muffler and the cabin resonance/drone between 2-3k is awful and if I'm forced to keep it there my ears really start to hurt. Top down though it's glorious so I've chose to live with it.
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07-12-2016, 02:49 AM
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#15
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Registered User
Join Date: Apr 2016
Location: Norway
Posts: 29
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Ok. I think this thred has nested up, and collected some information from previus threds.
I have now put the original exhaust back on. When i did, i found out that that the pipes on the circuit werks connecting to the C pipe is alittlebit thiner than the original. Therfore the clamps (tried original, and new ones) did not get a 100% seal. It was pretty tight so i dont think it would be mouch of a differense and would make the drone go away. All in all, the exhaust did not give me the good feeling.
I have read up and down the forum and internet about exhaust for the car, so this is my new plan;
I want to try the DIY PSE. I've found out that there is two different back boxes made originaly from Porsche. And those who have done the DIY has made it in two different ways. This has something to do with where the valved pipes are entering / exiting the outer chamber of back box (nerest C pipes). Some that have done the DIY has also left out the outer chamber.
My question is what solution to go for? How loud is the different solutions, to have a scale on this lets say the original is a 2 and circuit werks was a 8 of 10.
Does anyone have pictures of an open original PSE to see exactly where the pipes go?
I realy hope this thred will collect a good part of information that is out there in different threds and plases on the internet. Also that this wil help others!
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07-12-2016, 08:22 PM
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#16
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Registered User
Join Date: Apr 2014
Location: Fresno, CA
Posts: 8
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Quote:
Originally Posted by Carl.O
Hi.
I bought and installed the circuit werks exhaust from ebay.
The exhaust is fine over 3000 rpm but has wery loud resonance under 3000 rpm. Just the smalest step on the pedal and it's unberable.
Does anyone else have som experience with this exhaust or solutions to fix the resonance?
If not, I wil go back to stock or look for the PSE witch i think wil be a more comfortable balance betwen cruising and good sound over 3000 rpm
Carl
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I have the same exhaust as you. To get rid of the drone I inserted a single motorcycle baffle in the "s" pipe before the muffler. It will eliminate the drone. If you want even more quieter you can wrap the baffle with fiberglass motorcycle wrap. Motorcycles have this problem all the time with aftermarket exhausts.
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01-31-2017, 12:50 PM
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#17
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Registered User
Join Date: May 2016
Posts: 3
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ANy updates or other solutions for drone-age, esp. from Circuit Werks exhausts?
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