08-26-2010
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#1
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Admin
Join Date: Oct 2003
Location: Sportsman's Paradise, LA.
Posts: 5,382
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Collapsed Flex Section
Well after working out of town for the past 20 months I'm back home. Before I left to go work out of state I was having a problem with my car not wanting to build high boost. This is the reason why I haven't been running it much since my 11.45@126mph pass on 93 pump. I've been scratching my head over why I was having this issue. My main issue was excessive high exhaust manifold pressure related to intake boost pressure.
At 20 psi of intake boost I was getting 35 psi of exhaust pressure in the manifold for a 1.5:1 pressure ratio. Not great, but could be better.
But I was hitting a boost wall of 25-27 psi. My car would not build anymore boost, period. I even mechanically jam closed my waste gate to make sure it wasn't opening under boost. When this happened I would get 25 psi of intake boost pressure and 50 psi of exhaust manifold pressure. At 2:1 pressure ratio there was a problem.
Well I'm back home now and thanks to a thread on another forum I have found my problem.
This is my 3 inch s/s flex section from my new exhaust system seen here....
http://www.mitsustyle.com/forums/sho...t=16155&page=3
Anybody see a problem??? 
We cut the internal webbing bands and pulled it out. Still has the external webbing for support.
__________________
"You don't have a clue. You couldn't get a clue during the clue mating season in a field full of horny clues if you smeared your body with clue musk and did the clue mating dance."
When she get's bitchy, SPANK THAT ASS! (#Y#)
Last edited by 1ViciousGSX; 08-27-2010 at 12:07 AM..
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08-26-2010
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#2
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Pewp Champion
Join Date: Nov 2003
Location: Blaine
Drives: Teh Bean
Posts: 12,309
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Re: Collapsed Flex section
Wow, well at least you found the problem.
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08-26-2010
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#3
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Admin
Join Date: Oct 2003
Location: Sportsman's Paradise, LA.
Posts: 5,382
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Re: Collapsed Flex Section
Now to hammer out that 10 sec pass.
__________________
"You don't have a clue. You couldn't get a clue during the clue mating season in a field full of horny clues if you smeared your body with clue musk and did the clue mating dance."
When she get's bitchy, SPANK THAT ASS! (#Y#)
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08-27-2010
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#4
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Pewp Champion
Join Date: Nov 2003
Location: Blaine
Drives: Teh Bean
Posts: 12,309
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Re: Collapsed Flex Section
Get on it! Racing this weekend?
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08-27-2010
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#5
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Admin
Join Date: Oct 2003
Location: Sportsman's Paradise, LA.
Posts: 5,382
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Re: Collapsed Flex Section
Quote:
Originally Posted by Halon
Get on it! Racing this weekend?
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Not yet, still ridiculously hot here in Louisiana, but once it starts to cool off,.............. It's on.
__________________
"You don't have a clue. You couldn't get a clue during the clue mating season in a field full of horny clues if you smeared your body with clue musk and did the clue mating dance."
When she get's bitchy, SPANK THAT ASS! (#Y#)
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08-27-2010
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#6
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'2of9'
Join Date: Nov 2004
Location: Inver Grove Heights
Drives: Racer Van V6
Posts: 2,125
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Re: Collapsed Flex Section
there are nails on the ground, thus, nails are in your tires?? hahaha jk. That is one heck of a nice white 2gb you got there! so clean...so clean...
__________________
ლ(ಠ益ಠლ)
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08-27-2010
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#7
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Transmission destroyer
Join Date: Feb 2007
Location: Cambridge
Drives: G37, 91 TSi
Posts: 7,150
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Re: Collapsed Flex Section
Crazy. Glad you found it, it's been forever since you've posted anything but politics haha
__________________
Quote:
Originally Posted by scheides
I swing from the nuts of cold hard data. Anything less is a guess.
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08-27-2010
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#8
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immune from paybans
Join Date: Oct 2005
Location: West Des Moines
Drives: poorly
Posts: 4,358
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Re: Collapsed Flex Section
Wow, didn't know that could happen. With the internals out, is it going to leak? Not a big deal I suppose, maybe just a bit louder?
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08-27-2010
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#9
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aka Goodbye
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Re: Collapsed Flex Section
This is happening a lot lately.
__________________
2009 Corvette Z51-SOLD
1992 Mitsubishi Eclipse GSX-SOLD
2013 BMW Z4-Current summer hooptie
2017 GMC Yukon-Current winter hooptie
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08-27-2010
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#10
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Admin
Join Date: Oct 2003
Location: Sportsman's Paradise, LA.
Posts: 5,382
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Re: Collapsed Flex Section
Quote:
Originally Posted by asshanson
Wow, didn't know that could happen. With the internals out, is it going to leak? Not a big deal I suppose, maybe just a bit louder?
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It won't leak, the webbing is only there to support the bellows section, but it's solid, no leaks.
Now the real question is,............... how much of a problem was this when I made the 11.45@126 / 22psi pass??? Immediately after making that pass I only did three things, installed the FP4R cams, poured in some C16 and cranked up the boost. And that is when I had the problem start showing itself, the engine choked off at 25 psi.
__________________
"You don't have a clue. You couldn't get a clue during the clue mating season in a field full of horny clues if you smeared your body with clue musk and did the clue mating dance."
When she get's bitchy, SPANK THAT ASS! (#Y#)
Last edited by 1ViciousGSX; 08-27-2010 at 09:07 AM..
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08-27-2010
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#11
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Pewp Champion
Join Date: Nov 2003
Location: Blaine
Drives: Teh Bean
Posts: 12,309
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Re: Collapsed Flex Section
Quote:
Originally Posted by Goat Blower
This is happening a lot lately.
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Really? Any idea what causes this? |
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08-27-2010
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#12
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Admin
Join Date: Oct 2003
Location: Sportsman's Paradise, LA.
Posts: 5,382
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Re: Collapsed Flex Section
Quote:
Originally Posted by Halon
Really? Any idea what causes this?
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I would say expansion and velocity of the exhaust gasses.
__________________
"You don't have a clue. You couldn't get a clue during the clue mating season in a field full of horny clues if you smeared your body with clue musk and did the clue mating dance."
When she get's bitchy, SPANK THAT ASS! (#Y#)
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08-27-2010
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#13
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flips McGee
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Re: Collapsed Flex Section
That flex section seems excessively long too man, maybe put in a shorter one this time?
That really sucks though, can't wait to see what she'll do now!
__________________
Quote:
Originally Posted by Murlo26
I need to listen to Scheides more often i think :)
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Quote:
Originally Posted by turbotalon1g
...I realized that I can't keep up my shit talking without anything to back it up.
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Quote:
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Originally Posted by JV
S2000: For those of us that know the Miata is the best car on the planet, but also want extra power and to not have to turn in our man cards.
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08-27-2010
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#14
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Admin
Join Date: Oct 2003
Location: Sportsman's Paradise, LA.
Posts: 5,382
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Re: Collapsed Flex Section
Quote:
Originally Posted by scheides
That flex section seems excessively long too man, maybe put in a shorter one this time?
That really sucks though, can't wait to see what she'll do now!
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It's 12 inches long and under the oil pan. I'm not changing it, just took the internal webbing out.
I would have put a 3.5 inch diameter flex in there, but it wouldn't fit. As you can see, the 3 inch diameter is very tight.
__________________
"You don't have a clue. You couldn't get a clue during the clue mating season in a field full of horny clues if you smeared your body with clue musk and did the clue mating dance."
When she get's bitchy, SPANK THAT ASS! (#Y#)
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08-27-2010
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#15
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formerly ecoli
Join Date: Oct 2003
Location: On the dyno
Posts: 4,892
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Re: Collapsed Flex Section
Didn't this same exact thing happen to Hal or someone just recently?
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08-27-2010
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#16
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Admin
Join Date: Oct 2003
Location: Sportsman's Paradise, LA.
Posts: 5,382
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Re: Collapsed Flex Section
Quote:
Originally Posted by ecoli
Didn't this same exact thing happen to Hal or someone just recently?
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Yes, it was his thread that made me look.
__________________
"You don't have a clue. You couldn't get a clue during the clue mating season in a field full of horny clues if you smeared your body with clue musk and did the clue mating dance."
When she get's bitchy, SPANK THAT ASS! (#Y#)
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08-27-2010
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#17
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N17r0U$ br4D
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Re: Collapsed Flex Section
That sucks but nice that you figured it out.
I'm liking that vband placement, you wouldn't have to pull the whole exhaust to do a tranny swap. All you would have to do us undo two bolts and take the hanger off.
__________________
My rice rocket best times
Pump Gas: 8.85 @ 152.3 in 2016
Race Gas: 8.982 @ 152.16 in 2014
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08-27-2010
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#18
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aka Goodbye
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Re: Collapsed Flex Section
I'm wondering how many other people this has happened to that didn't cut the pipe apart to find out. From Hal's thread, there seems to be some correlation with running E85.
__________________
2009 Corvette Z51-SOLD
1992 Mitsubishi Eclipse GSX-SOLD
2013 BMW Z4-Current summer hooptie
2017 GMC Yukon-Current winter hooptie
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08-27-2010
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#19
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Pewp Champion
Join Date: Nov 2003
Location: Blaine
Drives: Teh Bean
Posts: 12,309
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Re: Collapsed Flex Section
I just went and looked at mine for the heck of it. Mine doesn't have the woven mesh in the inside at all so no problem here. After seeing this I think I'll make sure to avoid flex sections with it on the inside.
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08-27-2010
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#20
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Admin
Join Date: Oct 2003
Location: Sportsman's Paradise, LA.
Posts: 5,382
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Re: Collapsed Flex Section
Quote:
Originally Posted by Goat Blower
I'm wondering how many other people this has happened to that didn't cut the pipe apart to find out. From Hal's thread, there seems to be some correlation with running E85.
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Mine resulted while running 93 octane pump (or E10 as we call it down here  ). As soon as I put C16 and turned up the boost for the first time the restriction was already there. I still think it has to do with heat expansion and velocity.
__________________
"You don't have a clue. You couldn't get a clue during the clue mating season in a field full of horny clues if you smeared your body with clue musk and did the clue mating dance."
When she get's bitchy, SPANK THAT ASS! (#Y#)
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