Home » Public Forums » GMCnet » Quiet Exhaust Question?
| Quiet Exhaust Question? [message #368539] |
Sun, 23 January 2022 14:27  |
g r a n t
Messages: 22
Registered: March 2021
Karma: 0
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Junior Member |
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Hello,
I've gone back into previous posts but can't quite find what I am looking for.
I have a '75 Eleganza with the 455.
It was purchased with recently installed dual mufflers. I don't know what kind as the coach is currently hibernating.
While I appreciate a hotrod from afar I'm not partial to driving around waking up the neighbours in the campgrounds.
Maybe I've been driving Toyotas and riding BMWs too long.
I'm wondering about muffling the exhaust note without having an adverse affect on the system i.e. having to re-tune the machine or something like that.
My mechanic mentioned maybe adding a resonator.
I've found a few posts about resonators.
Is a resonator designed for my purpose? Will it muffle the noise at low speeds in the neighbourhood etc?
What are your recommendations?
Thank you.
Grant
1975 Eleganza
Toronto, ON
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| Re: Quiet Exhaust Question? [message #368542 is a reply to message #368539] |
Sun, 23 January 2022 16:51  |
Bullitthead
Messages: 1411
Registered: November 2013
Karma: 5
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Senior Member |
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Mine is quiet with 2 mufflers up front and a long pipe to the right rear corner. Pipe is 2.5 inch diameter. If I ever woke anybody up in a campground they must have been sleeping in the road. Maybe the insides of one or both of your mufflers has corroded away and is not cancelling the sound wave. Headers up front are definitely louder than cast iron manifolds and I also have those courtesy of the P.O.. I also have the fender liners installed. Sitting in the driver's seat I can barely hear the engine running. Engine tuning can make a big difference in the amount of sound emitted from headers, but usually more sound will be accompanied by loss of normal power output and poor fuel economy. If it runs well and smooth I would check/replace the mufflers first,especially since I have the equipment to tackle that job. A resonator is just another muffler and will quiet it more (and eliminate exhaust "crack") but also may cost just as much to procure and get installed as replacing the mufflers. Depends on where and how you shop.
Terry Kelpien
ASE Master Technician
73 Glacier 260
Smithfield, Va.
[Updated on: Sun, 23 January 2022 16:52] Report message to a moderator |
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| Re: Quiet Exhaust Question? [message #368551 is a reply to message #368542] |
Mon, 24 January 2022 12:54 |
g r a n t
Messages: 22
Registered: March 2021
Karma: 0
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Junior Member |
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Hello Bullitthead,
Thanks for the notes. Yes, I have the 455 with headers. I know the noise level is subjective but I'm trying to get the 60s/70s hotrod rumble-at-idle toned down a bit. When I am at speed I don't hear the engine or exhaust much if at all (my fan clutch is another story). At idle or low speed going through the neighbourhood you definitely know I am there. I've always liked the stealth approach. This beast is not stealth. Ha! If it were a 64 Corvette I'd be happy. I'm just sensitive to others when starting the machine. The mufflers should still be good as they were recent but the PO did mention he liked the hotrod sound and may have chosen "louder" mufflers. I'll look into the resonator approach. Like I said, I may also be used to my 4Runner with 4 cat converters, a muffler and a resonator!! Thanks for the info.
1975 Eleganza
Toronto, ON
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| [GMCnet] Re: Quiet Exhaust Question? [message #368558 is a reply to message #368539] |
Tue, 25 January 2022 09:22 |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
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Senior Member |
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GM experimented with no mufflers, by denting the exhaust pipe as well as
the tailpipes. It was good when the cars were new, but the aftermarket
exhaust providers raised "HOLY NED" with them because they had to provide
similar exhaust systems. What usually happened was that the OEM stuff got
replaced from manifold flanges to end of tailpipe with conventional
systems. Customers were none to happy about the bills for that. GM changed
back in a couple of years. Then came "catastrophic convertes" resonators,
etc.
Jim Hupy
Salem, Oregon
On Tue, Jan 25, 2022, 7:13 AM Keith V wrote:
> I fixed the rap by running the exhaust straight out the back rather than
> pointed out the pass side. I barely hear it at all now 🙂
> ________________________________
> From: Terry via Gmclist
> Sent: Sunday, January 23, 2022 4:51 PM
> To: gmclist@list.gmcnet.org
> Cc: Terry
> Subject: [GMCnet] Re: Quiet Exhaust Question?
>
> Mine is quiet with 2 mufflers up front and a long pipe to the right rear
> corner. Pipe is 2.5 inch diameter. If I ever woke anybody up in a campground
> they must have been sleeping in the road. Maybe the insides of one or both
> of your mufflers has corroded away and is not cancelling the sound wave.
> Headers up front are definitely louder than cast iron manifolds and I also
> have those courtesy of the P.O.. I also have the fender liners installed.
> Sitting in the driver's seat I can barely hear the engine running. Engine
> tuning can make a big difference in the amount of sound emitted from
> headers, but usually will be accompanied by loss of normal power output
> and poor fuel economy. If it runs well and smooth I would check/replace the
> mufflers first,especially since I have the equipment to tackle that job. A
> resonator is just another muffler and will quiet it more (and eliminate
> exhaust "crack") but also may cost just as much to procure and get
> installed as replacing the mufflers. Depends on where and how you shop.
> --
> Terry Kelpien
>
> ASE Master Technician
>
> 73 Glacier 260
>
> Smithfield, Va.
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
>
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
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| [GMCnet] Re: Quiet Exhaust Question? [message #368559 is a reply to message #368542] |
Tue, 25 January 2022 08:58 |
Keith V
Messages: 2337
Registered: March 2008
Location: Mounds View,MN
Karma: 0
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Senior Member |
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I fixed the rap by running the exhaust straight out the back rather than pointed out the pass side. I barely hear it at all now 🙂
________________________________
From: Terry via Gmclist
Sent: Sunday, January 23, 2022 4:51 PM
To: gmclist@list.gmcnet.org
Cc: Terry
Subject: [GMCnet] Re: Quiet Exhaust Question?
Mine is quiet with 2 mufflers up front and a long pipe to the right rear corner. Pipe is 2.5 inch diameter. If I ever woke anybody up in a campground
they must have been sleeping in the road. Maybe the insides of one or both of your mufflers has corroded away and is not cancelling the sound wave.
Headers up front are definitely louder than cast iron manifolds and I also have those courtesy of the P.O.. I also have the fender liners installed.
Sitting in the driver's seat I can barely hear the engine running. Engine tuning can make a big difference in the amount of sound emitted from
headers, but usually will be accompanied by loss of normal power output and poor fuel economy. If it runs well and smooth I would check/replace the
mufflers first,especially since I have the equipment to tackle that job. A resonator is just another muffler and will quiet it more (and eliminate
exhaust "crack") but also may cost just as much to procure and get installed as replacing the mufflers. Depends on where and how you shop.
--
Terry Kelpien
ASE Master Technician
73 Glacier 260
Smithfield, Va.
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
_______________________________________________
GMCnet mailing list
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Keith Vasilakes
Mounds View. MN
75 ex Royale GMC
ask me about MicroLevel
Cell, 763-732-3419
My427v8@hotmail.com
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| [GMCnet] Re: Quiet Exhaust Question? [message #368560 is a reply to message #368558] |
Tue, 25 January 2022 10:23 |
jimk
Messages: 6734
Registered: July 2006
Location: Belmont, CA
Karma: 9
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Senior Member |
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There is a reason why on a RV we prefer to exit to the side and down.
When towing a car, it is preferable not to have the Hot air hitting
directly onto them. Also less chance of bending the pipe tip. If you use a
DB meter, the noise outside is the same if the pipe exits to the rear or
side. Just sound different inside.
On Tue, Jan 25, 2022 at 7:22 AM James Hupy wrote:
> GM experimented with no mufflers, by denting the exhaust pipe as well as
> the tailpipes. It was good when the cars were new, but the aftermarket
> exhaust providers raised "HOLY NED" with them because they had to provide
> similar exhaust systems. What usually happened was that the OEM stuff got
> replaced from manifold flanges to end of tailpipe with conventional
> systems. Customers were none to happy about the bills for that. GM changed
> back in a couple of years. Then came "catastrophic convertes" resonators,
> etc.
> Jim Hupy
> Salem, Oregon
>
> On Tue, Jan 25, 2022, 7:13 AM Keith V wrote:
>
>> I fixed the rap by running the exhaust straight out the back rather than
>> pointed out the pass side. I barely hear it at all now 🙂
>> ________________________________
>> From: Terry via Gmclist
>> Sent: Sunday, January 23, 2022 4:51 PM
>> To: gmclist@list.gmcnet.org
>> Cc: Terry
>> Subject: [GMCnet] Re: Quiet Exhaust Question?
>>
>> Mine is quiet with 2 mufflers up front and a long pipe to the right rear
>> corner. Pipe is 2.5 inch diameter. If I ever woke anybody up in a
> campground
>> they must have been sleeping in the road. Maybe the insides of one or
> both
>> of your mufflers has corroded away and is not cancelling the sound wave.
>> Headers up front are definitely louder than cast iron manifolds and I
> also
>> have those courtesy of the P.O.. I also have the fender liners installed.
>> Sitting in the driver's seat I can barely hear the engine running. Engine
>> tuning can make a big difference in the amount of sound emitted from
>> headers, but usually will be accompanied by loss of normal power output
>> and poor fuel economy. If it runs well and smooth I would check/replace
> the
>> mufflers first,especially since I have the equipment to tackle that job.
> A
>> resonator is just another muffler and will quiet it more (and eliminate
>> exhaust "crack") but also may cost just as much to procure and get
>> installed as replacing the mufflers. Depends on where and how you shop.
>> --
>> Terry Kelpien
>>
>> ASE Master Technician
>>
>> 73 Glacier 260
>>
>> Smithfield, Va.
>> _______________________________________________
>> GMCnet mailing list
>> Unsubscribe or Change List Options:
>> _______________________________________________
>> GMCnet mailing list
>> Unsubscribe or Change List Options:
>>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
>
--
Jim Kanomata ASE
Applied/GMC, Newark,CA
jimk@appliedairfilters.com
http://www.gmcrvparts.com
1-800-752-7502
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
Jim Kanomata
Applied/GMC
jimk@appliedairfilters.com
www.appliedgmc.com
1-800-752-7502
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| [GMCnet] Re: Quiet Exhaust Question? [message #368561 is a reply to message #368560] |
Tue, 25 January 2022 10:53 |
sgltrac
Messages: 2797
Registered: April 2011
Karma: 1
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Senior Member |
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Jim’s comment reminds me of a lesson learned while dune riding a dirt bike
with the fiberglass pole and flag required for visibility. If the
flag(which mounts via the rear axle) is installed on the muffler side the
hot gasses from the muffler quickly make short work of the fiberglass pole
despite the fact that the pole is several inches to more than a foot away
from the exhaust tip while underway.
Sully
Bellevue wa
On Tue, Jan 25, 2022 at 8:24 AM Jim Kanomata wrote:
> There is a reason why on a RV we prefer to exit to the side and down.
> When towing a car, it is preferable not to have the Hot air hitting
> directly onto them. Also less chance of bending the pipe tip. If you use a
> DB meter, the noise outside is the same if the pipe exits to the rear or
> side. Just sound different inside.
>
>
> On Tue, Jan 25, 2022 at 7:22 AM James Hupy wrote:
>
>> GM experimented with no mufflers, by denting the exhaust pipe as well as
>> the tailpipes. It was good when the cars were new, but the aftermarket
>> exhaust providers raised "HOLY NED" with them because they had to provide
>> similar exhaust systems. What usually happened was that the OEM stuff got
>> replaced from manifold flanges to end of tailpipe with conventional
>> systems. Customers were none to happy about the bills for that. GM
> changed
>> back in a couple of years. Then came "catastrophic convertes" resonators,
>> etc.
>> Jim Hupy
>> Salem, Oregon
>>
>> On Tue, Jan 25, 2022, 7:13 AM Keith V wrote:
>>
>>> I fixed the rap by running the exhaust straight out the back rather
> than
>>> pointed out the pass side. I barely hear it at all now 🙂
>>> ________________________________
>>> From: Terry via Gmclist
>>> Sent: Sunday, January 23, 2022 4:51 PM
>>> To: gmclist@list.gmcnet.org
>>> Cc: Terry
>>> Subject: [GMCnet] Re: Quiet Exhaust Question?
>>>
>>> Mine is quiet with 2 mufflers up front and a long pipe to the right
> rear
>>> corner. Pipe is 2.5 inch diameter. If I ever woke anybody up in a
>> campground
>>> they must have been sleeping in the road. Maybe the insides of one or
>> both
>>> of your mufflers has corroded away and is not cancelling the sound
> wave.
>>> Headers up front are definitely louder than cast iron manifolds and I
>> also
>>> have those courtesy of the P.O.. I also have the fender liners
> installed.
>>> Sitting in the driver's seat I can barely hear the engine running.
> Engine
>>> tuning can make a big difference in the amount of sound emitted from
>>> headers, but usually will be accompanied by loss of normal power output
>>> and poor fuel economy. If it runs well and smooth I would check/replace
>> the
>>> mufflers first,especially since I have the equipment to tackle that
> job.
>> A
>>> resonator is just another muffler and will quiet it more (and eliminate
>>> exhaust "crack") but also may cost just as much to procure and get
>>> installed as replacing the mufflers. Depends on where and how you shop.
>>> --
>>> Terry Kelpien
>>>
>>> ASE Master Technician
>>>
>>> 73 Glacier 260
>>>
>>> Smithfield, Va.
>>> _______________________________________________
>>> GMCnet mailing list
>>> Unsubscribe or Change List Options:
>>> _______________________________________________
>>> GMCnet mailing list
>>> Unsubscribe or Change List Options:
>>>
>> _______________________________________________
>> GMCnet mailing list
>> Unsubscribe or Change List Options:
>>
>
>
> --
> Jim Kanomata ASE
> Applied/GMC, Newark,CA
> jimk@appliedairfilters.com
> http://www.gmcrvparts.com
> 1-800-752-7502
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
>
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
Sully
77 Royale basket case.
Future motorhome land speed record holder(bucket list)
Seattle, Wa.
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| [GMCnet] Re: Quiet Exhaust Question? [message #368562 is a reply to message #368561] |
Tue, 25 January 2022 11:08 |
jimk
Messages: 6734
Registered: July 2006
Location: Belmont, CA
Karma: 9
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Senior Member |
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On our Air Filter side of the business, we spent lot of time in Clean rooms
verifying noise using the DB meter and soon realized there were considerable
factors we had to explain.
Naturally we use data from a location that had the lowest DB.
---------- Forwarded message ---------
From: Todd Sullivan
Date: Tue, Jan 25, 2022 at 8:53 AM
Subject: [GMCnet] Re: Quiet Exhaust Question?
To:
Jim’s comment reminds me of a lesson learned while dune riding a dirt bike
with the fiberglass pole and flag required for visibility. If the
flag(which mounts via the rear axle) is installed on the muffler side the
hot gasses from the muffler quickly make short work of the fiberglass pole
despite the fact that the pole is several inches to more than a foot away
from the exhaust tip while underway.
Sully
Bellevue wa
On Tue, Jan 25, 2022 at 8:24 AM Jim Kanomata wrote:
> There is a reason why on a RV we prefer to exit to the side and down.
> When towing a car, it is preferable not to have the Hot air hitting
> directly onto them. Also less chance of bending the pipe tip. If you use a
> DB meter, the noise outside is the same if the pipe exits to the rear or
> side. Just sound different inside.
>
>
> On Tue, Jan 25, 2022 at 7:22 AM James Hupy wrote:
>
>> GM experimented with no mufflers, by denting the exhaust pipe as well as
>> the tailpipes. It was good when the cars were new, but the aftermarket
>> exhaust providers raised "HOLY NED" with them because they had to
provide
>> similar exhaust systems. What usually happened was that the OEM stuff
got
>> replaced from manifold flanges to end of tailpipe with conventional
>> systems. Customers were none to happy about the bills for that. GM
> changed
>> back in a couple of years. Then came "catastrophic convertes"
resonators,
>> etc.
>> Jim Hupy
>> Salem, Oregon
>>
>> On Tue, Jan 25, 2022, 7:13 AM Keith V wrote:
>>
>>> I fixed the rap by running the exhaust straight out the back rather
> than
>>> pointed out the pass side. I barely hear it at all now 🙂
>>> ________________________________
>>> From: Terry via Gmclist
>>> Sent: Sunday, January 23, 2022 4:51 PM
>>> To: gmclist@list.gmcnet.org
>>> Cc: Terry
>>> Subject: [GMCnet] Re: Quiet Exhaust Question?
>>>
>>> Mine is quiet with 2 mufflers up front and a long pipe to the right
> rear
>>> corner. Pipe is 2.5 inch diameter. If I ever woke anybody up in a
>> campground
>>> they must have been sleeping in the road. Maybe the insides of one or
>> both
>>> of your mufflers has corroded away and is not cancelling the sound
> wave.
>>> Headers up front are definitely louder than cast iron manifolds and I
>> also
>>> have those courtesy of the P.O.. I also have the fender liners
> installed.
>>> Sitting in the driver's seat I can barely hear the engine running.
> Engine
>>> tuning can make a big difference in the amount of sound emitted from
>>> headers, but usually will be accompanied by loss of normal power
output
>>> and poor fuel economy. If it runs well and smooth I would
check/replace
>> the
>>> mufflers first,especially since I have the equipment to tackle that
> job.
>> A
>>> resonator is just another muffler and will quiet it more (and
eliminate
>>> exhaust "crack") but also may cost just as much to procure and get
>>> installed as replacing the mufflers. Depends on where and how you
shop.
>>> --
>>> Terry Kelpien
>>>
>>> ASE Master Technician
>>>
>>> 73 Glacier 260
>>>
>>> Smithfield, Va.
>>> _______________________________________________
>>> GMCnet mailing list
>>> Unsubscribe or Change List Options:
>>> _______________________________________________
>>> GMCnet mailing list
>>> Unsubscribe or Change List Options:
>>>
>> _______________________________________________
>> GMCnet mailing list
>> Unsubscribe or Change List Options:
>>
>
>
> --
> Jim Kanomata ASE
> Applied/GMC, Newark,CA
> jimk@appliedairfilters.com
> http://www.gmcrvparts.com
> 1-800-752-7502
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
>
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
--
Jim Kanomata ASE
Applied/GMC, Newark,CA
jimk@appliedairfilters.com
http://www.gmcrvparts.com
1-800-752-7502
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
Jim Kanomata
Applied/GMC
jimk@appliedairfilters.com
www.appliedgmc.com
1-800-752-7502
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| [GMCnet] Re: Quiet Exhaust Question? [message #368577 is a reply to message #368560] |
Wed, 26 January 2022 08:58 |
Keith V
Messages: 2337
Registered: March 2008
Location: Mounds View,MN
Karma: 0
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Senior Member |
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I'll remember that if I ever start towing anything!
________________________________
From: Jim Kanomata
Sent: Tuesday, January 25, 2022 10:23 AM
To: gmclist@list.gmcnet.org
Subject: [GMCnet] Re: Quiet Exhaust Question?
There is a reason why on a RV we prefer to exit to the side and down.
When towing a car, it is preferable not to have the Hot air hitting
directly onto them. Also less chance of bending the pipe tip. If you use a
DB meter, the noise outside is the same if the pipe exits to the rear or
side. Just sound different inside.
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
Keith Vasilakes
Mounds View. MN
75 ex Royale GMC
ask me about MicroLevel
Cell, 763-732-3419
My427v8@hotmail.com
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