Pro's and Con's of Cat Converters??
12-26-2007, 06:35 PM
#46
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Check out Random Technology. They don't list a bolt on cat on their website, but if you send them one, they will make an exact high flow duplicate of it. It will mount up just like stock.
12-27-2007, 02:07 PM
#47
Cast Iron Man
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Patrick, a "test pipe" is a pipe, put in the place of the "cat" to test the difference of a clear or clogged cat.
For testing purposes(of course), You can get a large cat and weld a straight pipe through it to give it the look of a cat but with the feature of a test pipe.
For testing purposes(of course), You can get a large cat and weld a straight pipe through it to give it the look of a cat but with the feature of a test pipe.
12-27-2007, 02:25 PM
#49
Cast Iron Man
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12-27-2007, 06:22 PM
#50
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i am surprised that after all this time, nobody has tested/posted a stock exhaust comparison with/without cat.
a local 951 buddy is planning on this, so hopefully we'll have one up soon.
a local 951 buddy is planning on this, so hopefully we'll have one up soon.
12-27-2007, 07:49 PM
#51
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12-27-2007, 07:59 PM
#53
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Yeah but 50 hp/tq is pretty convincing. You're right in that a 20yr clogged cat is not going to do you any favours. Wonder on new cat v's no cat?
12-28-2007, 09:39 AM
#54
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Although it is hard to separate the MAF impact from the cat impact, my guess is that adding the Cat made very little difference."
12-28-2007, 12:25 PM
#55
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It would seem that there is no definitive info out there so far. Having both options seems the way to go, yes?
12-28-2007, 06:14 PM
#56
Patrick, I think it is a sizing issue for the HP expected... assuming you use a quality high flow system. Even 22 years ago with technology as it was at that time, Porsche lists identical HP and TQ for the cat and non cat versions... there is a slight difference in fuel consumption.
The obvious issue with the 50 HP/TQ difference above is that the cat was 20 years old and the cells had probably partially collapsed. I think the other issue is one of sizing... it would have been sized for a particular HP and my guess is that once you start to exceed that, you will get a difference with and without.
I think Seattle951 is a better indication... MAF change 1psi less boost and an extra 4 hp with cat... seems difficult to imagine cat detracted too much from that result.
The obvious issue with the 50 HP/TQ difference above is that the cat was 20 years old and the cells had probably partially collapsed. I think the other issue is one of sizing... it would have been sized for a particular HP and my guess is that once you start to exceed that, you will get a difference with and without.
I think Seattle951 is a better indication... MAF change 1psi less boost and an extra 4 hp with cat... seems difficult to imagine cat detracted too much from that result.
12-28-2007, 07:57 PM
#57
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So you reckon just bite the bullet and get a permanent one?
12-28-2007, 08:31 PM
#58
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I'm planning to go to a 3" system with no cat in two weeks when people get back to work. I don't know whether we have the "sniffers" down here. I'll have to drive discretely!
12-28-2007, 08:38 PM
#59
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i don't understand why 951 owners are so paranoid about emissions testing without the cat. all three cars i've owned have easily passed emissions testing with the cat removed.
12-28-2007, 08:50 PM
#60
Well I think it depends on your HP target and what size cat's available. Hence my suggestion of splitting into twins if a big enough cat is not available for the application... provided that can be made to fit of course.
If a big enough cat is not available and twins won't work out, then the switchable pipe comes into play. It is something you may choose to do anyway, as it would probably have soem benefit, I just suspect it would probably be pretty marginal if the cat is sized correctly. Your cat would no doubt last longer if it were not punished on the track though.
If a big enough cat is not available and twins won't work out, then the switchable pipe comes into play. It is something you may choose to do anyway, as it would probably have soem benefit, I just suspect it would probably be pretty marginal if the cat is sized correctly. Your cat would no doubt last longer if it were not punished on the track though.