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1981 931 - Need replacement catalytic converter

 
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canyonblaster  



Joined: 20 Aug 2012
Posts: 381
Location: Denver, CO, USA

PostPosted: Tue May 01, 2018 9:59 am    Post subject: 1981 931 - Need replacement catalytic converter Reply with quote

Cross posting from part wanted section.
Appreciate any advice!

http://www.924board.org/viewtopic.php?t=43696
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PCA Licensed Club Racer & Driving Instructor, Current cars: 1981 931, 2005 996 GT3, 2013 Cayenne GTS
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canyonblaster  



Joined: 20 Aug 2012
Posts: 381
Location: Denver, CO, USA

PostPosted: Mon May 07, 2018 5:56 am    Post subject: Reply with quote

ZERO luck but I did find a hollowed out one available @ Parts Heaven.
Anyone have insight as to how the car will perform & sound with a hollow cat?

Thx
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924RACR  



Joined: 29 Jul 2001
Posts: 8077
Location: Royal Oak, MI, USA

PostPosted: Mon May 07, 2018 11:09 pm    Post subject: Reply with quote

Should work well with a rodded-out cat... or check with Dan (ideola), I'd almost swear I gave him one years back, might still have it as a valid spare...
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'79 924 #77 ITB racecar
'82 931 Plat. Silver
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Carrera RSR  



Joined: 08 Jan 2010
Posts: 1530
Location: Somerset, UK

PostPosted: Tue May 08, 2018 5:29 am    Post subject: Reply with quote

Why bother with a Cat? Straight through pipe fwiw!
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1980 931 - forged pistons, Piper cam, CGT turbo, 951 ducted FMIC, custom intake, Mittelmotor dizzy & cam pulley, H&S exhaust, GAZ Gold, Fuch'ed, Quaife LSD
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3forall  



Joined: 29 May 2015
Posts: 17
Location: Canada

PostPosted: Tue May 08, 2018 7:21 am    Post subject: Reply with quote

I'd say replace it with a cheap resonator. Without the cat (straight) it gets too loud and the resonator helps the sound be a little less agricultural.
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1982 931 - Megasquirt and liquid intercooler
1969 911
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canyonblaster  



Joined: 20 Aug 2012
Posts: 381
Location: Denver, CO, USA

PostPosted: Tue May 08, 2018 7:53 am    Post subject: Reply with quote

Thx guys. I don't want it too loud, I already have a rear muffler delete with a low restriction Ansa/Monza type twin tip. It actually sounds great currently (other than the rattle from this old cat).

I like the idea of less restriction but don't I need the replacement piece to have the connector for the bypass pipe the car has? I'm not very savvy about how to deal with this.

Thx!
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Carrera RSR  



Joined: 08 Jan 2010
Posts: 1530
Location: Somerset, UK

PostPosted: Tue May 08, 2018 6:09 pm    Post subject: Reply with quote

You are best off without any restriction/mid box/cat between the turbo and back box. Change the back box size to tune the sound you are happy with. The turbo naturally reduces the note. The back bock reduces further with limited back pressure/restriction for better spool up.
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1980 931 - forged pistons, Piper cam, CGT turbo, 951 ducted FMIC, custom intake, Mittelmotor dizzy & cam pulley, H&S exhaust, GAZ Gold, Fuch'ed, Quaife LSD
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canyonblaster  



Joined: 20 Aug 2012
Posts: 381
Location: Denver, CO, USA

PostPosted: Thu May 10, 2018 2:05 pm    Post subject: Reply with quote

The car has to pass emissions every five years. Next test is in 2 years. Local emissions center mgr says it has to have a visible CAT. He also warned that although it only has a to pass an idle test (not a full roller test), w/o a CAT it may not pass....

I may have a line on a used OEM CAT with lower miles, and Parts Heaven in California has a hollowed out CAT for sale. Not sure what to do.
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