# Stock Exhaust Diameter? - Need to Replace Rusted Section (1998 GA16)



## super20g (Feb 28, 2005)

I have a 98 GXE and need to fix a problem where the flanges that connect the muffler to the rear exhaust section have rusted through and caused the gasket to fail.

It is not in my budget currently to replace both the rear exhaust pipe and muffler, so I am looking to just chop the flanges off an inch or so on both sides and welding a piece of pipe inbetween.

I am looking to find out what the diameter of the stock exhaust is and if anyone has done this recently, what size pipe would fit snungly over the stock pipe?

Thank you for your time and help!


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## GA16DE (Jun 23, 2005)

Are you wanting to weld a sleeve over it, or just put something in between. Because a sleeve will just increase backpressure.

But I would think that the exhaust tubing would be the same dimensions as the tail pipe dimensions, so you could try measuring that to get inner/outer diameters. Someone please correct me if I'm wrong.


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## super20g (Feb 28, 2005)

Yes, I was thinking of just choppping the flanges and welding a sleeve over the pipe with a mig welder. 

Do you think this will really increase the backpressure much more than welding a section of the same diameter inbetween? 

I am talking a 6" or less length and was planning to find a tight fitting sleeve.

BTW, does anyone know the stock diameter? Best sleeve size?


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## GA16DE (Jun 23, 2005)

I can go try to measure the diameter at the muffler inlet after dinner if someone doesn't know.

And as far as increasing the backpressure, I'm not 100% sure whether it would be more than welding in a section, but I would assume so because it's expanding and then contracting right back down, but again I'm not positive on that.


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## IanH (Feb 11, 2003)

Since you are not chocking it down, but going larger i think any affect on the flow will be so small as to be un-noticeable. I think the previous poster thought you were proposing going smaller.


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## GA16DE (Jun 23, 2005)

No, I was thinking in terms of the exhaust gases expanding to fit the sleeve and then hitting the bump when they get to the rest of the exhaust and causing the flow to be more turbulent.


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## IanH (Feb 11, 2003)

well if you looked inside a muffler you would see this in extreme's, also the gas flow is not simple smooth flow, its not laminar and viscous, its already turbulent. So the step is small, and the boundary layer means that the gas next to the pipe is stationary, and speeds up as it moves away from the boundary. So I believe you willnot see an effect. If it was near the exhaust ports where the gases are moving faster with a bigger step you could get reflections. 
when this is has been done deliberately at the exhaust ports to header, the header is oversized by as much as 1/4 inch to get the desired backflow reflections away from the ports.
Of course the other way around with header smaller than the port is a disaster....


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## super20g (Feb 28, 2005)

Sooo... does anyone have a 2+" caliper handy and can measure the OD of the stock exhaust? Or know approximately off hand? I do not have access to the car at this time. Around 1.5"? 1.75"? I have googled and searched this forum but havent came up with anything yet for the 95-99 GA16's yet. Thanks.


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## IanH (Feb 11, 2003)

Sorry sold my 1.6GA, you need to say whether you need before the muffler or after, they are often different sizes.


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## super20g (Feb 28, 2005)

I assumed they were the same, but I need before and after the flange that connects the stock muffler to the stock rear exhaust pipe section. Thanks.


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## PTXer (Aug 31, 2006)

super20g said:


> Sooo... does anyone have a 2+" caliper handy and can measure the OD of the stock exhaust? QUOTE]
> My '97 is 1.7940" O.D. if you haven't got it yet.


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## super20g (Feb 28, 2005)

PTXer,

I REALLY appreciate the measurement!

Now I can go buy a section of exhaust pipe and go get this welded up!

Well, when we get power back from Hurricaine Ike that is... I live in Indiana and we had a hurricaine?? Go figure.


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## IanH (Feb 11, 2003)

So do u think this is 1 3/4 ID tubing 22 or 24 gauge ?


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