Dumb exhaust question

Alfisti · 06-13-2022, 01:06 PM

So I have an opportunity to buy a used cross pipes, tried and tested on the 997 with great success. Retail is about $1400CAD new. I can pick one up used for $400 but there is a good sized dent in one of the pipes, image is below.

Should I consider this or just walk away? I have no idea if this affects performance or sound in any way? Gut reaction is to walk away, repair will likely cost enough that i may as well just go new.

pz619 · 06-13-2022, 01:17 PM

Yeah I think I would walk. That’s a fairly significant dent which appears to reduce the interior volume by roughly 30-40% in that section. I have to imagine there is some performance loss there as it’s now a bottleneck to some degree.

freakystyly · 06-13-2022, 02:04 PM

Not sure about context for this but sometimes pipes can come dented intentionally to clear bracing or other parts. Is that the case here? if not, yeah, skip it.

Steeler · 06-13-2022, 02:33 PM

My.02 is that the piece that is damaged looks like a fairly straight piece. A simple fix and should not be too pricey a repair at a welding shop. Assuming it is run of the mill stainless steel.

grannyknot · 06-13-2022, 03:54 PM

Quote:

Originally Posted by Steeler

My.02 is that the piece that is damaged looks like a fairly straight piece. A simple fix and should not be too pricey a repair at a welding shop. Assuming it is run of the mill stainless steel.

Exactly, cut out the dent and weld a patch on top.
Who is going to see it? Don't pass up a good deal like that.
If you are willing to drive up to my place I'll do it for free.

Burrcold · 06-13-2022, 04:02 PM

Most decent exhaust shops can pressurize the pipe, heat it up and form it back into shape. To be honest, I doubt you would notice a difference installing it with the dent.

AlexFL · 06-13-2022, 04:14 PM

WTF. Looks like a corroded piece of junk from a scrap yard. Tell the person to give it to you for free.

Burrcold · 06-13-2022, 04:55 PM

Quote:

Originally Posted by AlexFL

WTF. Looks like a corroded piece of junk from a scrap yard. Tell the person to give it to you for free.

It's surface rust lol you live in Florida...this is normal up here.

gilberjj · 06-13-2022, 05:17 PM

Engine Masters did a fantastic video on this exact thing. They progressively dented some headers more and more to see if it effected power output. In short, no, it didn't really matter. I say save the $1,000 and pick them up!
Video can be found here:
https://www.dailymotion.com/video/x3vupq0

AlexFL · 06-13-2022, 05:27 PM

Quote:

Originally Posted by Burrcold

It's surface rust lol you live in Florida...this is normal up here.

Man, have you never been in FL? We have 100% humidity for 8 months in a year.

Burrcold · 06-13-2022, 05:32 PM

Quote:

Originally Posted by AlexFL

Man, have you never been in FL? We have 100% humidity for 8 months in a year.

I certainly have...every year for the past 30 years! Road salt still does more on parts than humidity (even mixed with salty ocean air).

///MPhatic · 06-13-2022, 05:58 PM

That's nothing to be concerned about. Even if the flange is bent a bit your exhaust shop can heat it up and fit it with ease. Run to this deal, don't walk.

chad86tsi · 06-13-2022, 06:17 PM

That would take ~$250-350 to fix correctly, assuming you have a shop that is qualified and wants that kind of work. Correctly means cutting it out and replacing with a fresh patch which requires a donor piece of mandrel bent material of the correct size and grade, and using a TIG process with 309 or 312 rod. Probably a 2 hour job and $50 in material. I wouldn't use any other method. I manufacture stainless turbo manifolds and stainless exhaust systems, and that repair is not difficult, but would give me pause if I didn't have a solution lined up.

The material looks like aged 409 stainless, which is a lower grade, does a magnet stick to it?

Given it's location in the exhaust stream that flow disruption isn't going to cause major harmonic imbalances, but it's still big enough have some impact, and is enough to bother me so I'd fix it if it were mine.

Redd · 06-13-2022, 06:57 PM

Tbh that 'dent' looks like it may have been intentional, maybe to clear something. I don't see any strike marks/scratches to indicate it hit something. And the dent shape is just too perfect for it to have been made by accident.

Alfisti · 06-13-2022, 07:40 PM

Thanks for all of the replies, even if no two of you can agree!

Suds · 06-13-2022, 08:14 PM

I watched an episode of Motor Trend Engine Masters where they had to severely smash (close off) a header tube to see a change with the motor on a dyno. Offer $200 or walk.

https://www.motortrend.com/news/engi...-dont-have-to/

06-13-2022, 01:06 PM	#1
Alfisti Brigadier General 6496 Rep 3,030 Posts Drives: 2008 Saab 9-3 Combi Join Date: Nov 2014 Location: Toronto, Canada iTrader: (0)	Dumb exhaust question So I have an opportunity to buy a used cross pipes, tried and tested on the 997 with great success. Retail is about $1400CAD new. I can pick one up used for $400 but there is a good sized dent in one of the pipes, image is below. Should I consider this or just walk away? I have no idea if this affects performance or sound in any way? Gut reaction is to walk away, repair will likely cost enough that i may as well just go new.
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06-13-2022, 01:17 PM	#2
pz619 Brigadier General 3277 Rep 3,255 Posts Drives: F87 M2C 6MT, Tesla 3 Join Date: Oct 2013 Location: San Diego iTrader: (1)	Yeah I think I would walk. That’s a fairly significant dent which appears to reduce the interior volume by roughly 30-40% in that section. I have to imagine there is some performance loss there as it’s now a bottleneck to some degree.
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06-13-2022, 02:04 PM	#3
freakystyly Lieutenant Colonel 2919 Rep 1,785 Posts Drives: F22 B58 6MT Join Date: May 2016 Location: Ontario iTrader: (0)	Not sure about context for this but sometimes pipes can come dented intentionally to clear bracing or other parts. Is that the case here? if not, yeah, skip it.
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06-13-2022, 02:33 PM	#4
Steeler Colonel 2428 Rep 2,702 Posts Drives: Built not Bought 04 Z4 VF Join Date: Feb 2013 Location: Kitchener Ontario Canada iTrader: (2)	My.02 is that the piece that is damaged looks like a fairly straight piece. A simple fix and should not be too pricey a repair at a welding shop. Assuming it is run of the mill stainless steel. __________________ W2A Intercooled Vortech V3Si, custom ducting, Alpha N, 60# Bosch,2.62 pulley, multi port WMI, Severn Tuning(pokeybritches), Tial, magnaflow,SS race muffler, 42 design,3.91LSD, H&R, Hotchkis,ST coils,Konis, Megan camber arms, AKG SS, Nylon mounts, Poly bushings, Carbon interior, CF Aero.APEX
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06-13-2022, 04:02 PM	#6
Burrcold Brigadier General 5209 Rep 3,928 Posts Drives: 2024 M3 Comp xDrive Join Date: Oct 2019 Location: Toronto, Canada iTrader: (0)	Most decent exhaust shops can pressurize the pipe, heat it up and form it back into shape. To be honest, I doubt you would notice a difference installing it with the dent. __________________ Current: 2024 BMW M3 Competition xDrive \| 2022 Audi Q7 Gone: 2022 Audi RS5 \| 2020 BMW M340i \| 2019 Audi RS5
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06-13-2022, 04:14 PM	#7
AlexFL Brigadier General 7834 Rep 4,607 Posts Drives: BMW Join Date: Jun 2019 Location: South Florida iTrader: (0)	WTF. Looks like a corroded piece of junk from a scrap yard. Tell the person to give it to you for free.
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06-13-2022, 05:17 PM	#9
gilberjj Second Lieutenant 95 Rep 221 Posts Drives: E92 M3 Join Date: May 2020 Location: Vancouver, WA iTrader: (2)	Engine Masters did a fantastic video on this exact thing. They progressively dented some headers more and more to see if it effected power output. In short, no, it didn't really matter. I say save the $1,000 and pick them up! Video can be found here: https://www.dailymotion.com/video/x3vupq0
	Appreciate 0 Quote

06-13-2022, 05:58 PM	#12
///MPhatic The Seeker 13764 Rep 3,296 Posts Drives: OG M2 • Exige Join Date: Aug 2008 Location: USA iTrader: (2)	That's nothing to be concerned about. Even if the flange is bent a bit your exhaust shop can heat it up and fit it with ease. Run to this deal, don't walk.
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06-13-2022, 06:17 PM	#13
chad86tsi Captain 1605 Rep 787 Posts Drives: 2019 BMW M760i P60 Greyblack Join Date: Apr 2022 Location: Portland metro iTrader: (0)	That would take ~$250-350 to fix correctly, assuming you have a shop that is qualified and wants that kind of work. Correctly means cutting it out and replacing with a fresh patch which requires a donor piece of mandrel bent material of the correct size and grade, and using a TIG process with 309 or 312 rod. Probably a 2 hour job and $50 in material. I wouldn't use any other method. I manufacture stainless turbo manifolds and stainless exhaust systems, and that repair is not difficult, but would give me pause if I didn't have a solution lined up. The material looks like aged 409 stainless, which is a lower grade, does a magnet stick to it? Given it's location in the exhaust stream that flow disruption isn't going to cause major harmonic imbalances, but it's still big enough have some impact, and is enough to bother me so I'd fix it if it were mine.
	Appreciate 1 Dino GT35131.50 Quote

06-13-2022, 06:57 PM	#14
Redd Brigadier General 3893 Rep 4,155 Posts Drives: 2010 BMW E92 M3 Dakar Edition Join Date: Jul 2015 Location: Malaysia iTrader: (0)	Tbh that 'dent' looks like it may have been intentional, maybe to clear something. I don't see any strike marks/scratches to indicate it hit something. And the dent shape is just too perfect for it to have been made by accident.
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06-13-2022, 07:40 PM	#15
Alfisti Brigadier General 6496 Rep 3,030 Posts Drives: 2008 Saab 9-3 Combi Join Date: Nov 2014 Location: Toronto, Canada iTrader: (0)	Thanks for all of the replies, even if no two of you can agree!
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06-13-2022, 08:14 PM	#16
Suds /M Enthusiast 1597 Rep 1,617 Posts Drives: Responsiblish Join Date: Aug 2010 Location: Lone Star State iTrader: (1)	I watched an episode of Motor Trend Engine Masters where they had to severely smash (close off) a header tube to see a change with the motor on a dyno. Offer $200 or walk. https://www.motortrend.com/news/engi...-dont-have-to/ __________________ 2019 M2 Comp, Alpine White, DCT, track car build, 1/2 cage, AP Racing Brakes & Nitron Coilovers, BM3 Stage 1 93 Oct. 2018 Porsche Cayman GTS, Night Blue Metalic, PDK, COBB tuned 93 Oct. 2004 Audi A4 Avant USP 6mt, RS4 clutch, built motor, Garrett GT3071r "Big Ass Turbo" Motoza Tune
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