Hollowing out an LT5 cat on stock manifold. Anyone do it?
08-09-2018, 09:27 PM
#1
Zen Vet Master Level VII
Thread Starter
Hollowing out an LT5 cat on stock manifold. Anyone do it?
Has anyone ever "hollowed out" the cats on their stock LT5 exhaust manifold?
I'm doing my usual angst about exhaust upgrades on my 91 ZR1. I wondering how hollowing out the cats make a difference and if anyone had any experience with it.
I'm just curious....
I'm doing my usual angst about exhaust upgrades on my 91 ZR1. I wondering how hollowing out the cats make a difference and if anyone had any experience with it.
I'm just curious....
08-09-2018, 10:41 PM
#2
Race Director
Fwiw todays caralytic convertors are so efficent it doesnt pay to hollow them out...
there is really no benefit to doing so
hth
there is really no benefit to doing so
hth
08-10-2018, 01:57 AM
#3
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Just bit the bullet and do headers/exhaust. 91 exhaust system is not the best flowing to start with.
08-10-2018, 05:51 AM
#4
Le Mans Master
the factory headers on the early cars are tough to modify and the big can cats are tough as nails and it's better to install the headers as suggested. cats really only cost around 5 hp and due to the turbulence of a big empty can they would likely not gain much due to very poor scavenging of the engine. no bueno, sell them and use the money to do the right thing.
the stainless works headers can be had cheaper now and the obx are around 500 and seem to be OK (like to hear more).
the exhaust needs all the help it can get to let the beast breathe
Last edited by Rkreigh; 08-10-2018 at 05:53 AM.
08-10-2018, 07:34 AM
#5
I agree
the factory headers on the early cars are tough to modify and the big can cats are tough as nails and it's better to install the headers as suggested. cats really only cost around 5 hp and due to the turbulence of a big empty can they would likely not gain much due to very poor scavenging of the engine. no bueno, sell them and use the money to do the right thing.
the stainless works headers can be had cheaper now and the obx are around 500 and seem to be OK (like to hear more).
the exhaust needs all the help it can get to let the beast breathe
the factory headers on the early cars are tough to modify and the big can cats are tough as nails and it's better to install the headers as suggested. cats really only cost around 5 hp and due to the turbulence of a big empty can they would likely not gain much due to very poor scavenging of the engine. no bueno, sell them and use the money to do the right thing.
the stainless works headers can be had cheaper now and the obx are around 500 and seem to be OK (like to hear more).
the exhaust needs all the help it can get to let the beast breathe
08-10-2018, 08:26 AM
#6
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I agree
the factory headers on the early cars are tough to modify and the big can cats are tough as nails and it's better to install the headers as suggested. cats really only cost around 5 hp and due to the turbulence of a big empty can they would likely not gain much due to very poor scavenging of the engine. no bueno, sell them and use the money to do the right thing.
the stainless works headers can be had cheaper now and the obx are around 500 and seem to be OK (like to hear more).
the exhaust needs all the help it can get to let the beast breathe
the factory headers on the early cars are tough to modify and the big can cats are tough as nails and it's better to install the headers as suggested. cats really only cost around 5 hp and due to the turbulence of a big empty can they would likely not gain much due to very poor scavenging of the engine. no bueno, sell them and use the money to do the right thing.
the stainless works headers can be had cheaper now and the obx are around 500 and seem to be OK (like to hear more).
the exhaust needs all the help it can get to let the beast breathe
08-10-2018, 10:24 AM
#7
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I have SW long tube coated headers, yes they cost more but fit was perfect only modification was the oil dipstick mount that has to be done with any header and after almost 10 years the still look new no discoloration at all. I originally had the tied to a Flowmaster exhaust now have Corsa no drone with ether setup.
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08-10-2018, 02:59 PM
#8
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Yes, I had SW o my 92 several years back.... I didnt have mine coated, but yea, the fit was great and I did the install on my Kwiklift no problem. Just trying to save a buck and was hoping the OBX brand was a decent alternative.
08-11-2018, 11:01 AM
#11
Drifting
I have OBX headers, Flowmaster cats and an OBX exhaust. Fit and finish on the headers was shockingly good, if not down right excellent. I know several people with OBX headers, all fit perfectly with the exception of having to dimple the #1 exhaust pipe to clear the steering shaft. I understand that is not unique to the OBX brand. There is no drone from the exhaust and the tone is deep and mellow unlike a Corsa. Here’s what you get at a very reasonable price.
H
H
08-11-2018, 03:45 PM
#12
I have OBX headers, Flowmaster cats and an OBX exhaust. Fit and finish on the headers was shockingly good, if not down right excellent. I know several people with OBX headers, all fit perfectly with the exception of having to dimple the #1 exhaust pipe to clear the steering shaft. I understand that is not unique to the OBX brand. There is no drone from the exhaust and the tone is deep and mellow unlike a Corsa. Here’s what you get at a very reasonable price.
H
H
I think SW headers are around triple the price..
08-11-2018, 04:43 PM
#14
Drifting
If I had to do it over again I would have had them coated or wrapped.
H
Last edited by ccmano; 08-11-2018 at 04:45 PM.
08-11-2018, 08:13 PM
#15
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I have OBX headers, Flowmaster cats and an OBX exhaust. Fit and finish on the headers was shockingly good, if not down right excellent. I know several people with OBX headers, all fit perfectly with the exception of having to dimple the #1 exhaust pipe to clear the steering shaft. I understand that is not unique to the OBX brand. There is no drone from the exhaust and the tone is deep and mellow unlike a Corsa. Here’s what you get at a very reasonable price.
H
H
Those look to be coated or chromed? They look pretty good aesthetically anyway. Did you need wire extensions for the O2 sensors? I think I had to get some with my SW headers IIRC.... Would band type clamps work? I sold my welder a few years ago... so I cant really weld them up. I have an X Pipe in place of the resonator and aftermarket mufflers that I cannot figure out what brand.... no numbers, no name on them.... nice though, polished stainless and they sound great really....Id kind of like to keep the air injection system
08-11-2018, 09:22 PM
#16
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Yes you need to extend the 02 wires, SW sells the with and without AIR hook-up.
08-27-2018, 11:18 PM
#17
Le Mans Master
93 and on had a design change preventing the ingestion. If yours is a 90 or 91 running with original cats I would hollow them out or replace them.
08-28-2018, 10:49 AM
#18
Drifting
Hey Hans...
Those look to be coated or chromed? They look pretty good aesthetically anyway. Did you need wire extensions for the O2 sensors? I think I had to get some with my SW headers IIRC.... Would band type clamps work? I sold my welder a few years ago... so I cant really weld them up. I have an X Pipe in place of the resonator and aftermarket mufflers that I cannot figure out what brand.... no numbers, no name on them.... nice though, polished stainless and they sound great really....Id kind of like to keep the air injection system
Those look to be coated or chromed? They look pretty good aesthetically anyway. Did you need wire extensions for the O2 sensors? I think I had to get some with my SW headers IIRC.... Would band type clamps work? I sold my welder a few years ago... so I cant really weld them up. I have an X Pipe in place of the resonator and aftermarket mufflers that I cannot figure out what brand.... no numbers, no name on them.... nice though, polished stainless and they sound great really....Id kind of like to keep the air injection system
H
Last edited by ccmano; 08-28-2018 at 10:51 AM.