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Exhaust Drone!

Old 12-23-2017, 02:10 PM
  #21  
383vett
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One more suggestion. I run open ARH longtubes. The noise is not so bad after donning a helmet.
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Old 12-23-2017, 02:15 PM
  #22  
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Originally Posted by billschroeder5842 View Post
So, for zero/lo drone your choice is either Corsa Mufflers or a OEM/Walker solution. Frankly it dosen't matter what you do upstream.
I don't think this is strictly true at all. In practical terms, this advice may be helpful, but the reality is that it's the total system length and diameter that affect resonance (Helmholtz theory). The Corsa mufflers work with resonance tuning, too, so they are an easy way to address the issues. But as my car shows, they are neither the only way nor a sure-fire way to cancel every bit of drone.

Originally Posted by ddahlgren
I had often thought the drone or at least part of it comes from the rear window cargo area floor combination. Anyone with a vert and top down care to comment?
I think this is accurate. FWIW, I always run with the glass top on my car instead of the fiberglass one. It's actually louder inside with the glass top on than with no top on the car! It's clearly reflecting from the back hatch floor right onto the passenger's ears. Just putting a moving blanket or other soft blanket on the rear hatch floor makes the interior way quieter.

PS - Or just wear a helmet all the time, LOL!

Last edited by MatthewMiller; 12-23-2017 at 02:15 PM.
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Old 12-23-2017, 03:32 PM
  #23  
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I had the oem reproductions on mine for a while. It just ended up being too quiet for me. Then I ended up with mid america's muffler eliminators. Drone is more or less the same and with the top on and windows up you have no problem holding a conversation. Not as loud as straight up muffler eliminators but you hear me take off from the light half a mile down the road in my backyard. My drone occurs around 3000 rpms which is pretty much only while accelerating... I have never been in a c4 with corsa mufflers so I can not comment. Also the 84 oem mufflers point at the ground instead of running out the back.

If you really want to know why I switched mufflers, here is the comparison between the two. Not that you would want to watch or anything...
And a pull with the eliminators...

Last edited by 84 4+3; 12-23-2017 at 03:33 PM.
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Old 12-23-2017, 04:49 PM
  #24  
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Originally Posted by 84 4+3 View Post
I had the oem reproductions on mine for a while. It just ended up being too quiet for me. Then I ended up with mid america's muffler eliminators. Drone is more or less the same and with the top on and windows up you have no problem holding a conversation. Not as loud as straight up muffler eliminators but you hear me take off from the light half a mile down the road in my backyard. My drone occurs around 3000 rpms which is pretty much only while accelerating... I have never been in a c4 with corsa mufflers so I can not comment. Also the 84 oem mufflers point at the ground instead of running out the back.

If you really want to know why I switched mufflers, here is the comparison between the two. Not that you would want to watch or anything...
https://www.youtube.com/watch?v=IgChF2U027A
And a pull with the eliminators...
https://www.youtube.com/watch?v=R4oa...UK7HLw&index=6
thanks for vids... really helps... do you still have original engine?
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Old 12-23-2017, 04:59 PM
  #25  
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Originally Posted by frankinvett84 View Post
thanks for vids... really helps... do you still have original engine?
The first video is bone stock l83. The second is after a very, very mild cam and an intake swap. The cam is very similar to the 89 l98 cam but flat tappet and with a lower lsa. Both videos have the magnaflow "high flow" cat on the car.

I've been told the later oem reproduction mufflers (walker) produce a bit more external sound while retaining the low levels of drone. The 84 was very quiet stock so gm allegedly made the later cars louder.
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Old 12-23-2017, 05:13 PM
  #26  
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Am I correct??? Dynomax IS Walker???
I just looked on Zipps website...
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Old 12-24-2017, 06:02 AM
  #27  
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I have headman headers, x pipe, no cats and no drone.
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Old 12-24-2017, 08:16 AM
  #28  
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I have hedman headers, and a X pipe....no cats...I stuck two little red "cherry bomb" glas packs into the ends of the x pipe and continued the pipes out the back. No drone at all...but you know I'm coming...
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Old 12-24-2017, 11:01 AM
  #29  
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Originally Posted by ghoastrider1 View Post
I have headman headers, x pipe, no cats and no drone.
could you tell me which mufflers you are using? if any
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Old 12-26-2017, 08:35 AM
  #30  
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I have a Y pipe 2 1/5 inch I think w/no cats magnaflow cat and Borla cat back. It will make your ears bleed with drone at cruising speeds. I have raced cars for over 45 years and this is just plain annoying.
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Old 12-26-2017, 09:01 AM
  #31  
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Originally Posted by ddahlgren View Post
I have a Y pipe 2 1/5 inch I think w/no cats magnaflow cat and Borla cat back. It will make your ears bleed with drone at cruising speeds. I have raced cars for over 45 years and this is just plain annoying.
I think the Borla is designed to be a noise maker for nostalgia if someone wanted to even swap mine with a Corsa, I'd be all over it. My cat back is too good to be dumped in the trash can so even if I get lucky enough and buy a used Corsa, 11415 and get it installed, I still have to do something about the used Borla. Kinda like herpes. Bad decision to go raw on the wrong girl and you pay for it for life.
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Old 12-26-2017, 10:39 AM
  #32  
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Borla was the only performance one in budget that fit my 91. Magnaflow ran directly into ebrake cable and bracket.

Last edited by ddahlgren; 12-26-2017 at 10:39 AM.
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Old 12-26-2017, 12:25 PM
  #33  
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Originally Posted by aklim View Post
Kinda like herpes. Bad decision to go raw on the wrong girl and you pay for it for life.
Aklim, again you manage to put the problem in complete perspective.
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Old 12-26-2017, 12:37 PM
  #34  
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Originally Posted by billschroeder5842 View Post
Aklim, again you manage to put the problem in complete perspective.
Well, I'm still paying for it with a noisy exhaust
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Old 12-26-2017, 03:03 PM
  #35  
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Originally Posted by aklim View Post
I have TPIS headers that Y into the cat. Any suggestions?
I'm a bit confused. I suggested the H pipe to the OP. I would venture it would help you as well.

My ('69) headers dump into a Y behind the transmission, and Y back out under the differential to the two Dynomax mufflers at the rear. I did the single pipe between the two Y pipes because one big pipe weighs less than two smaller pipes. Despite the two Y pipes I still had drone at 1500 RPM. Installing the H pipe between the collector reducers got rid of most of the drone. The car is actually quite pleasant at non-WOT speeds.
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Old 12-26-2017, 03:14 PM
  #36  
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Originally Posted by billschroeder5842 View Post
This is correct.

Franklin, you are wanting a bit of both ends of the spectrum; high performance low restriction that yeilds big power and throaty sound.... but with no drone. (corsa fans jump in here and smack me)

You have to have a strategy and then go for balance and your definition of balance.

Of all the countless threads on this subject the only consistent "Zero Drone" solutions come from choice of THE MUFFLERS and not combinations of the headers, cross over, X pipes etc. 2.5 vs 3 inch pipes.

So, for zero/lo drone your choice is either Corsa Mufflers or a OEM/Walker solution. Frankly it dosen't matter what you do upstream.
Nonsense. The energy and the frequency content that results in the bodywork resonating/droning comes from upstream (ie: the engine exhaust pulses). Things that change the noise frequency or magnitude of that exhaust noise have a definite affect on the amount of bodywork drone. Mufflers are just one of several items in the system that will impact the drone problem.
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Old 12-26-2017, 03:15 PM
  #37  
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Originally Posted by 69427 View Post
I'm a bit confused. I suggested the H pipe to the OP. I would venture it would help you as well.

My ('69) headers dump into a Y behind the transmission, and Y back out under the differential to the two Dynomax mufflers at the rear. I did the single pipe between the two Y pipes because one big pipe weighs less than two smaller pipes. Despite the two Y pipes I still had drone at 1500 RPM. Installing the H pipe between the collector reducers got rid of most of the drone. The car is actually quite pleasant at non-WOT speeds.
I have a drone without 4 tube headers. And the solution is?
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Old 12-26-2017, 03:37 PM
  #38  
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Originally Posted by 69427 View Post
I'm a bit confused. I suggested the H pipe to the OP. I would venture it would help you as well.

My ('69) headers dump into a Y behind the transmission, and Y back out under the differential to the two Dynomax mufflers at the rear. I did the single pipe between the two Y pipes because one big pipe weighs less than two smaller pipes. Despite the two Y pipes I still had drone at 1500 RPM. Installing the H pipe between the collector reducers got rid of most of the drone. The car is actually quite pleasant at non-WOT speeds.
I was hoping someone could show me what they did for a car like mine. I have the TPIS LT headers that go into the Y pipe so I am not sure how to put a H pipe in that unless you remove the Y and install some sort of H pipe.
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Old 12-26-2017, 04:39 PM
  #39  
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I have an X pipe where the cat. converter used to be located. so where would I put the H? Why wouldn't the X pipe do whatever the H pipe was going to do? I dont mind loud exhaust. Its the harmonic DRONE that is in a small band of the RPM range. Ive checked its from 13-18ish hundred rpm. Im thinking of extending muffler tips out past end of valance.
Also was I correct when I saw Walker is Dynomax ? because thars what I have. they are about ten years old bought from Ecklers. like others have stated one side is functional. are they the same peeps said there was no drone with earlier?
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Old 12-26-2017, 04:46 PM
  #40  
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Not sure how I would go about doing that since the Y goes into the cat
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