|
924Board.org Discussion Forum of 924.org
|
View previous topic :: View next topic |
Author |
Message |
canyonblaster
Joined: 20 Aug 2012 Posts: 391 Location: Denver, CO, USA
|
Posted: Tue May 01, 2018 8:59 am Post subject: 1981 931 - Need replacement catalytic converter |
|
|
Cross posting from part wanted section.
Appreciate any advice!
http://www.924board.org/viewtopic.php?t=43696 _________________ PCA Licensed Club Racer & Driving Instructor Current P cars: 1981 931
Past P cars, 1985 944, 1987 951, 1990 911 C4, 2002 Boxster S, 2005 996 GT3, 2013 911 C2S
Daily Driver P cars: 2008 Cayenne GTS, 2013 Cayenne GTS |
|
Back to top |
|
|
canyonblaster
Joined: 20 Aug 2012 Posts: 391 Location: Denver, CO, USA
|
Posted: Mon May 07, 2018 4:56 am Post subject: |
|
|
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 _________________ PCA Licensed Club Racer & Driving Instructor Current P cars: 1981 931
Past P cars, 1985 944, 1987 951, 1990 911 C4, 2002 Boxster S, 2005 996 GT3, 2013 911 C2S
Daily Driver P cars: 2008 Cayenne GTS, 2013 Cayenne GTS |
|
Back to top |
|
|
924RACR
Joined: 29 Jul 2001 Posts: 8815 Location: Royal Oak, MI, USA
|
Posted: Mon May 07, 2018 10:09 pm Post subject: |
|
|
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... _________________ Vaughan Scott
Webmeister
'79 924 #77 SCCA H Prod racecar
'82 931 Plat. Silver
#25 Hidari Firefly P2 sports prototype |
|
Back to top |
|
|
Carrera RSR
Joined: 08 Jan 2010 Posts: 2309 Location: Somerset, UK
|
Posted: Tue May 08, 2018 4:29 am Post subject: |
|
|
Why bother with a Cat? Straight through pipe fwiw! _________________ 1980 931 - forged pistons, Piper cam, K27/26 3257 6.10 hybrid turbo, 951 FMIC, custom intake, Mittelmotor dizzy & cam pulley, H&S exhaust, GAZ Gold, Fuch'ed, Quaife
Now www.924board.org/viewtopic.php?t=34690
Then www.924board.org/viewtopic.php?t=31252 |
|
Back to top |
|
|
3forall
Joined: 29 May 2015 Posts: 17 Location: Canada
|
Posted: Tue May 08, 2018 6:21 am Post subject: |
|
|
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. _________________ 1981 924 Weissach edition
1982 931 - Megasquirt and liquid intercooler
1969 911 |
|
Back to top |
|
|
canyonblaster
Joined: 20 Aug 2012 Posts: 391 Location: Denver, CO, USA
|
Posted: Tue May 08, 2018 6:53 am Post subject: |
|
|
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! _________________ PCA Licensed Club Racer & Driving Instructor Current P cars: 1981 931
Past P cars, 1985 944, 1987 951, 1990 911 C4, 2002 Boxster S, 2005 996 GT3, 2013 911 C2S
Daily Driver P cars: 2008 Cayenne GTS, 2013 Cayenne GTS |
|
Back to top |
|
|
Carrera RSR
Joined: 08 Jan 2010 Posts: 2309 Location: Somerset, UK
|
Posted: Tue May 08, 2018 5:09 pm Post subject: |
|
|
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. _________________ 1980 931 - forged pistons, Piper cam, K27/26 3257 6.10 hybrid turbo, 951 FMIC, custom intake, Mittelmotor dizzy & cam pulley, H&S exhaust, GAZ Gold, Fuch'ed, Quaife
Now www.924board.org/viewtopic.php?t=34690
Then www.924board.org/viewtopic.php?t=31252 |
|
Back to top |
|
|
canyonblaster
Joined: 20 Aug 2012 Posts: 391 Location: Denver, CO, USA
|
Posted: Thu May 10, 2018 1:05 pm Post subject: |
|
|
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. _________________ PCA Licensed Club Racer & Driving Instructor Current P cars: 1981 931
Past P cars, 1985 944, 1987 951, 1990 911 C4, 2002 Boxster S, 2005 996 GT3, 2013 911 C2S
Daily Driver P cars: 2008 Cayenne GTS, 2013 Cayenne GTS |
|
Back to top |
|
|
canyonblaster
Joined: 20 Aug 2012 Posts: 391 Location: Denver, CO, USA
|
Posted: Sun Jun 10, 2018 4:17 am Post subject: |
|
|
This is a bummer... In trying to chase down the annoying rattle noise coming from somewhere around the exhaust, my tech thought it was the CAT. Well, he removed my exhaust and gutted the cat, AND cut open the resonator just behind the CAT, removed the insulation and some kind of retaining ring that was broken anyway, and welded it all up and put it back on...
The rattle remains and is now louder! Ugh.
It my be anything. Possibly the turbo bearings?
THE WORST part is this, now the car won't spool up and build nearly as much boost. I have a gauge and it was making 10 psi @ 4-5K and now it struggles to get to 5-6 at ANY RPM.....
Is this from lack of back pressure? Now what am I going to do!? _________________ PCA Licensed Club Racer & Driving Instructor Current P cars: 1981 931
Past P cars, 1985 944, 1987 951, 1990 911 C4, 2002 Boxster S, 2005 996 GT3, 2013 911 C2S
Daily Driver P cars: 2008 Cayenne GTS, 2013 Cayenne GTS |
|
Back to top |
|
|
Fasteddie313
Joined: 29 Sep 2013 Posts: 2596 Location: MI
|
Posted: Sun Jun 10, 2018 4:25 am Post subject: |
|
|
Could be the pop off valve in the compressor housing rattling and now leaking boost by badly?
I suppose a broken WG (waste gate)spring could cause these symptoms too but I'm not sure if that ever happens..
Post a video of the noise and other symptoms.
I don't think you would hear turbo bearings until you hear the wheels hitting the housings, and you would be smoking like crazy..
Is the turbo not spinning up or just not building pressure?
If the pop off valve is leaking and rattling it would spool like crazy and make little boost..
But, if the WG is leaking and rattling the turbo wouldn't spool for crap but still give whatever boost you get from the little spooling it will do..
Take your air compressor and dial it down to like 10-15psi..
Take the WG signal line off your upper charge tube and actuate your WG by blowing air pressure in that line.. You should hear a really creeky springing noise and it will slam back shut when you release the pressure..
If it doesn't do anything try it up to about 30psi but I wouldn't go any higher than that..
Do you pull 1st gear to redline at WOT atleast once every time you drive the car as the manual suggests? _________________ 80 Turbo - Slightly Modified |
|
Back to top |
|
|
canyonblaster
Joined: 20 Aug 2012 Posts: 391 Location: Denver, CO, USA
|
Posted: Sun Jun 10, 2018 5:45 am Post subject: |
|
|
Thanks! I wish I could find one local tech who really understands this car....they all seem to chase their tail.... _________________ PCA Licensed Club Racer & Driving Instructor Current P cars: 1981 931
Past P cars, 1985 944, 1987 951, 1990 911 C4, 2002 Boxster S, 2005 996 GT3, 2013 911 C2S
Daily Driver P cars: 2008 Cayenne GTS, 2013 Cayenne GTS |
|
Back to top |
|
|
Carrera RSR
Joined: 08 Jan 2010 Posts: 2309 Location: Somerset, UK
|
Posted: Mon Jun 11, 2018 12:13 am Post subject: |
|
|
The turbo recirc valve and it’s spring can rattle. Mines done this since it’s rebuild on and off. Will only do it on idle as there’s no boost to seat it.
A boost leak will reduce boost. Possibly a slightly gapped recirc valve
I burst wastegate membrane will overboost not underboost. A wastegate stuck open may cause under boost but would also cause the turbo to overspin _________________ 1980 931 - forged pistons, Piper cam, K27/26 3257 6.10 hybrid turbo, 951 FMIC, custom intake, Mittelmotor dizzy & cam pulley, H&S exhaust, GAZ Gold, Fuch'ed, Quaife
Now www.924board.org/viewtopic.php?t=34690
Then www.924board.org/viewtopic.php?t=31252 |
|
Back to top |
|
|
|
|
You cannot post new topics in this forum You cannot reply to topics in this forum You cannot edit your posts in this forum You cannot delete your posts in this forum You cannot vote in polls in this forum
|
Powered by phpBB © 2001, 2005 phpBB Group
|