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 Mufflers: How hot do they get
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Bill Boyle
Horse Feathers (Charter Member)

USA
5357 Posts

Posted - 25 Sep 2009 :  09:25:09 AM  Show Profile  Visit Bill Boyle's Homepage  Reply with Quote
Location, location, location! Logically the closer mufflers are located to the engine the hotter they get because of the hot exhaust. Mufflers located in front of the rear axle, therefore must be hotter than a transverse cross flow muffler sitting in the crevice space between the axle and gas tank. Should there be a concern about the temperature of the muffler as it is quite close to the fuel tank. Was Pontiac concerned with this location and safety? Did GM protect the tank with a heat shield. To my knowledge, I think the answer is no, however; I'm not sure. Anyone with a transverse muffler set up on an F-body know? This has crossed my mind after installing the Pypes transverse muffler on my 79 TA. Finally, just how hot do mufflers get? Anyone do a temperature test?

"Dedicated to keeping the classic Pontiac engine alive."

----
400 bored +.030, forged TRW pistons, ported 62 heads, Hedman headers, 2.5 SS dual exhaust X Pypes, Comp 276AH10 cam, Scorpion 1.65 RR, 850 Q-jet, stock intake & tuned HEI; original owner.

bnorris_74
Crazy Horse

USA
1442 Posts

Posted - 25 Sep 2009 :  09:50:35 AM  Show Profile  Reply with Quote
No heat shield on my 74 Formula ever. I've had it since it was new.

Of course the infamous Pinto was made back in that time period albeit by a different manufacturer.
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67drake
Sitting Duck

Azerbaijan
1551 Posts

Posted - 25 Sep 2009 :  10:09:43 AM  Show Profile  Reply with Quote
FWIW,I had a first gen Camaro that was pretty original still. No heat shield of any kind there either.


71' GTO Original 400 M20 3.23 posi
13.95@102.1 MPH on street tires
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Cobrabill
Talking Dog

Aruba
3158 Posts

Posted - 26 Sep 2009 :  04:09:41 AM  Show Profile  Reply with Quote
Exhaust entering headers is about 13 to 1400 degrees.By the time it exits the tail pipes,it is down to 400 degrees.

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Bill Boyle
Horse Feathers (Charter Member)

USA
5357 Posts

Posted - 26 Sep 2009 :  07:46:00 AM  Show Profile  Visit Bill Boyle's Homepage  Reply with Quote
Anyone do testing using a pyrometer???

"Dedicated to keeping the classic Pontiac engine alive."

----
400 bored +.030, forged TRW pistons, ported 62 heads, Hedman headers, 2.5 SS dual exhaust X Pypes, Comp 276AH10 cam, Scorpion 1.65 RR, 850 Q-jet, stock intake & tuned HEI; original owner.
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Phil
The Great White Buffalo

USA
7304 Posts

Posted - 26 Sep 2009 :  08:22:26 AM  Show Profile  Reply with Quote
Bill, I have done some experimenting with one of my Powerstroke diesels. With a cockpit mounted pyrometer I have installed the sensor in the down pipe coming off the turbo, and later directly in the drivers side exhaust manifold.

Full throttle registers the highest readings (obviously). There is an approx. difference of 500 degrees by changing only the location of the sensor between the two locations!

It is amazing that there is that much loss in temperature for such a short length.

Also, FWIW my Blowmaster system on the Formula has a transverse muffler and it has a heat shield welded to the muffler on the side facing the gas tank.

Bowties are for Pee-wee Herman. LS swaps in Pontiacs should only apply to Fieros.
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Steve C.
Chief PONTIAC

2112 Posts

Posted - 26 Sep 2009 :  11:13:11 AM  Show Profile  Reply with Quote
Inorder to help with heat under the car I had my entire 3-inch exhaust system w/X-pipe ceramic coated. It looks great as well. The headers are the typical silver, and from the collectors back, including the mufflers, it's been coated black. The tailpipe sections not exposed are black and were masked to leave the exposed tips chrome.
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mike mcarthur
Pony that Jumps

USA
2475 Posts

Posted - 26 Sep 2009 :  11:36:15 AM  Show Profile  Visit mike mcarthur's Homepage  Reply with Quote
I've also had several of these cars over the years. Never seen a heat shield. FWIW, I was always told to put the mufflers as far back as possible because the exhaust has time to slow down on it's own before it hits the mufflers. Don't know if that has any merit to it.

It's the stuff you learn after you know it all that's important
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Cobrabill
Talking Dog

Aruba
3158 Posts

Posted - 26 Sep 2009 :  1:20:14 PM  Show Profile  Reply with Quote
Bill,How do you think Jim Hand came up with those numbers i posted?

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Quad
Tribal Scout

4 Posts

Posted - 02 Jan 2020 :  10:09:52 PM  Show Profile  Reply with Quote
"In order to help with heat under the car I had my entire 3-inch exhaust system w/X-pipe ceramic coated"

Hi Steve C. Did this also reduce noise levels?? I was thinking of using ceramic coating on the transverse muffler exterior to take the edge of the noise level.

And after 10 years does it still look great?

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Brian Baker
Mongo

USA
1067 Posts

Posted - 02 Jan 2020 :  11:43:58 PM  Show Profile  Reply with Quote
In my 35 years of playing with Pontiacs, I have never seen a 1st or 2nd gen. F-body equipped with the transverse muffler have a heat shield between it and the fuel tank. Concern over heat in that area is a non-issue.

I ran a Flowmaster transverse muffler on my old '78 T/A I owned in the early 90's. Headers with 2.5" pipes to the muffler and 2.5" tailpipes out to the rear bumper (straight out the back, no chrome turn-downs). The Flowmaster transverse was actually 2 mufflers in one...the passenger side pipe exited the driver side of the muffler, and vice versa. Never an issue with it, but it was loud and droned at highway speeds.

Will Rogers never met a liberal.
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Steve C.
Chief PONTIAC

2112 Posts

Posted - 03 Jan 2020 :  08:26:44 AM  Show Profile  Reply with Quote
"In order to help with heat under the car I had my entire 3-inch exhaust system w/X-pipe ceramic coated"

Hi Steve C. Did this also reduce noise levels??

And after 10 years does it still look great?


Quad,
My headers have always been coated over the years, the benefits of that are well documented. I did the rest of my exhaust system ceramic coated including the mufflers in black more for appearance than anything. Only the exhaust tips are chrome plated.
It is reported to help with heat. To be honest did it help from heat transfer inside the car I cannot say. I also have sonic and thermal mat installed under the carpet.Last time the car was up on a rack and I was under it I did not notice any deterioration that stood out, that said I was not inspecting for it.
The coating was done in May 2007.


https://www.jet-hot.com/articles/2018/6/29/5-important-reasons-you-should-ceramic-coat-your-exhaust-headers-and-turbo-parts

Edited by - Steve C. on 03 Jan 2020 08:53:56 AM
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Brian Baker
Mongo

USA
1067 Posts

Posted - 03 Jan 2020 :  11:30:52 PM  Show Profile  Reply with Quote
The heels of your feet will thank you during those hot Florida summers by putting that dynomat insulation under the carpet if you're running headers. That was a big problem on my '78 and '79 T/A, even here in Maryland. My heels would get cooked on long drives and actually feel like a burn (or sunburn).

Will Rogers never met a liberal.
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Quad
Tribal Scout

4 Posts

Posted - 07 Jan 2020 :  03:04:22 AM  Show Profile  Reply with Quote
When I changed from uncoated to thermal barrier coated headers I remember there was a large drop in firewall and cabin temperatures. That was in Feb 1998 and it was still hot but can not recall if there was any reduction in noise levels.

March 2015 installing Ram Air Restoration Enterprises Manifolds (that were coated by them) reduced heat to acceptable level. Very quiet compared to the tube headers.

A pypes x-pipe and transverse muffler was also done at the same time as the RARE manifolds. Pypes instructions do not mention any heat shield. The factory 1975 Pontiac Service Manual has sections on exhaust system installation and exhaust system clearances. No mention of any heat shield.

Sounds like I will have to replace the cheap underlay I have under the carpet to cut done the noise and reduce what is now a only a minor heat problem.

Thanks
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