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Discussion Starter · #1 ·
So I got the Godspeed downpipe installed and there was a vibrational clanging sound that I couldn't figure out. I was told putting on some exhuast tape could help and I am going to do that anyways but I figured out what was going on and it might be a normal problem.

If you install a downpipe and midpipe without doing the rest of the exhuast back, then you might be having the same sound. The downpipe that Godspeed makes takes place of the midpipe and downpipe and the stainless steel pipe that is so stiff pushed the exhuast back.

The rest of the stock exhaust was pushed back to a point where the muffler was banging into a piece of metal and the muffler wasn't even hanging anymore. :mad:

Well we used some tough wire and pulled the muffler over by the metal flange and connected it to the axle. Now the exhaust sounds great. No banging or clanging.....so if you're having this problem check it out! :D
 

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mine went on fine and i've tried it with a catback and with stock piping. though now with my catback on my paint is starting to MELT off right above where the tip is because the metal of the top is so hot and so close to the bumper

it's not really noticable and i bought some touch up paint to maybe fix it later on, no biggie, but i wont be winning any car shows now :p
 

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Discussion Starter · #3 ·
JimDab said:
mine went on fine and i've tried it with a catback and with stock piping. though now with my catback on my paint is starting to MELT off right above where the tip is because the metal of the top is so hot and so close to the bumper

it's not really noticable and i bought some touch up paint to maybe fix it later on, no biggie, but i wont be winning any car shows now :p
Dude that sux!! Is that a normal problem, cause completing the exhaust system was probably what I was going to do next! Would maybe some of that silicone spray stuff on the top of the muffler? :confused:

I know they sell that stuff at summitracing.com
 

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i'm sure it's not normal, it's just too high

when i had the catback on alone it didnt happen but probably because it didn't get so hot with the cats in place

and most exhausts dont do this, it's just that this one has full 3" piping and a 102mm outlet (4inch?), so it gets about one inch away from the paint. using different hangers would easily solve the problem but the damage is already done so i dont care anymore
 

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im gonna edit a picture of my exact exhaust really quick, hold on

this is a real picture of how it was when i had just installed it, right now it looks about the same except for the paint where i'm about to edit it with little scribbles :)
 

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when i had the catback on alone it didnt happen but probably because it didn't get so hot with the cats in place
I don't believe this is a correct statement, in fact quite the opposite... forcing air through the cats will actually heat it up further and produce higher EGT's... if we remember Ideal gas law PV = nRT considering V R & n wont change your adding P to force it through the cats thus T goes up to compensate... well something like that anyway. I would say you have something lined up wrong now if this didn't happen before you changed your DP and it is now.
 

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but air gets restricted at the cats and less air goes through
i think youre just thinking too deeply

forumulas aside, less hot air gets through, so less hot air is present to heat up the metal piping
 

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Discussion Starter · #10 ·
MustGoFast said:
I don't believe this is a correct statement, in fact quite the opposite... forcing air through the cats will actually heat it up further and produce higher EGT's... if we remember Ideal gas law PV = nRT considering V R & n wont change your adding P to force it through the cats thus T goes up to compensate... well something like that anyway. I would say you have something lined up wrong now if this didn't happen before you changed your DP and it is now.
Having the cats in place would actually help drop the temperature because of what you described. *only reason I know this is because I am a chemical engineer at KU right now* The ideal gas law does hold true (pretty much) for this but the catalytic converters help drop the temperature. n, V, and R are constant since it is a constant flow rate of exhaust gas through a pretty much constant inside diameter pipe.

The important thing to note is that catalytic converters will actually make the pressure of the gas drop becuase it takes pressure to push them through there. Just like in the intercooler, pressure drop of the air through the device. Well when the pressure drops the only other thing that can compensate to keep the ideal gas law true is for the temperature of the gas to drop also. So you have the right info on the subject, but the pressure drops over the cats will drop the temperature too.

Fun with chemical engineering!!!:D
 

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Discussion Starter · #11 ·
God said:
Hmm, very strange. I have fitted many a car wiith my downpipe and stock exhaust and had no problem with it pushing the exhaust back. It shouldn't. Is your downpipe one piece?
Yeah, I got my downpipe from you Dan. This is Brian Cook from Lawrence who bought the used downpipe from the trade in on the new 350 Z guy! :)
 

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heh, no thanks

it's really not noticable unless you're looking at that part of the car. even a glance at the exhaust while standing and you won't even notice it since it's mostly from the under-side of the bumper

it does bother me somewhat but i'm just going to adjust the exhaust a little later on with longer hangers or something, and then put some touch-up paint on the under part to make it look good
 

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cook32 said:
Yeah, I got my downpipe from you Dan. This is Brian Cook from Lawrence who bought the used downpipe from the trade in on the new 350 Z guy! :)
Now that's REALLY puzzing considering I have fitted that exact downpipe on a stock exhaust WRX (the guy who had it before you) and it fit perfectly. Might want to give me a call today to see if I can troubleshoot.
 
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