C4 Tech/Performance L98 Corvette and LT1 Corvette Technical Info, Internal Engine, External Engine

Eliminate pre cats?

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Old 08-06-2007, 07:26 PM
  #21  
Kool88vette
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OK, I call Exotic Muscle and the front 2 1/2" Y pipe is on the way. The stock pipe is not mandrel bent and is 2 1/4" So I'm sure it will free up a couple of ponies. What do you think of cutting the 2 1/2" pipe and adding two of these to keep it legal. They claim to be super high flow. If I can open up the exhaust it's worth it to me. I would like long tubes but you know how the laws are here. http://rpmoutlet.com/powercat.htm
Old 08-06-2007, 08:32 PM
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davidnclearlaketx
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It just sucks that Cali has such strict emissions regulations!

Would be nice to do a manifold back no cat system!

As everyone drives their choked up emission compliant cars right past the big refineries and chemical plants spewing out crap in the air daily....
It's all about the $$$ for the big guys and the taxes, fees and other BS for us little guys.

Old 08-06-2007, 09:07 PM
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BADDUCK
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Originally Posted by Kool88vette
OK, I call Exotic Muscle and the front 2 1/2" Y pipe is on the way. The stock pipe is not mandrel bent and is 2 1/4" So I'm sure it will free up a couple of ponies. What do you think of cutting the 2 1/2" pipe and adding two of these to keep it legal. They claim to be super high flow. If I can open up the exhaust it's worth it to me. I would like long tubes but you know how the laws are here. http://rpmoutlet.com/powercat.htm
I would try it without them first. you can always add later.
Old 08-06-2007, 10:24 PM
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Kool88vette
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Originally Posted by BADDUCK
I would try it without them first. you can always add later.
You mean when I get caught?
Old 08-06-2007, 10:31 PM
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Kool88vette
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Originally Posted by davidnclearlaketx
It just sucks that Cali has such strict emissions regulations!

Would be nice to do a manifold back no cat system!

As everyone drives their choked up emission compliant cars right past the big refineries and chemical plants spewing out crap in the air daily....
It's all about the $$$ for the big guys and the taxes, fees and other BS for us little guys.

In California your car has to pass a visual inspection before it's put on the sniffer. I was planning to put on true dual exhaust with two cats and two precats. It would have opened the exhaust and burned cleaner. Then I found out it would not pass a visual inspection. It would have flunked even if the emissions were ultra clean.
Old 08-07-2007, 12:48 AM
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davidnclearlaketx
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That sucks!

Do you have any friends in close by states? NV maybe?
Maybe you could register your car at your friends address in another state that has not so strict emissions testing/requirements.
Glad I don't live in Cali!
Old 08-07-2007, 07:11 AM
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combustables
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I lived in california for 19 years. It is NOT a car friendly state. At ALL!!!! There was a time when a referendum was put through to simply outlaw cars older than 25 years. Needless to say, Socal reacted heavily and shot that down period. How dare they Is all I could think about.

Most visual inspections focus on things like broken or loose pipes, wires, muffler hangers etc. Most inspectors don't know anything about vettes much less that early C4's had and needed pre-cats on the y-pipe. Nobody would have failed inspection over that ...

I changed my front y pipe a stainless steel pipe and only regretted that the noise got definitly louder. I eventually used DEI header wrap on the new front pipe and got the noise back down to normal (whatever that was).

As an added bonus, I noticed that the header wrap completely took away all the creeks and croaks that the exhaust system used to make whenever I shut the car off. It doesn't do that anymore compared to a C5 vette which I noticed doing at the gocery store parking lot. The lady was still getting her purse etc. and I could already hear that stuff... Havent heard any C6's doing it yet :-)
Old 08-07-2007, 07:43 AM
  #28  
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Originally Posted by Kool88vette
In California your car has to pass a visual inspection before it's put on the sniffer. I was planning to put on true dual exhaust with two cats and two precats. It would have opened the exhaust and burned cleaner. Then I found out it would not pass a visual inspection. It would have flunked even if the emissions were ultra clean.
If you are going to put precats back on why go through all this? Any gains you might have is in the main high flow cat and cat back anyway. You won't be able to tell any difference from stock, your wallet will just be $300 lighter. I already went through this in stages. If you do go through with it, have it all welded or it will eventually leak and rattle with all those joints.
Old 08-07-2007, 10:26 AM
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Originally Posted by BADDUCK
If you are going to put precats back on why go through all this? Any gains you might have is in the main high flow cat and cat back anyway. You won't be able to tell any difference from stock, your wallet will just be $300 lighter. I already went through this in stages. If you do go through with it, have it all welded or it will eventually leak and rattle with all those joints.
Your exhaust will not be optimized if you have a choke point. The stock Y pipe is 2 1/4" and not mandrel bent. The new Y pipe is 2 1/2" mandrel bent. The pipe should increase HP. The precats are 20 years old, restrictive and probably somewhat clogged. The new precats flow much better. I think the Y-pipe is the choke point in my exhaust. I have a Carsound cat and catbacks.
Old 08-07-2007, 10:34 AM
  #30  
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Originally Posted by leefarah
I lived in california for 19 years. It is NOT a car friendly state. At ALL!!!! There was a time when a referendum was put through to simply outlaw cars older than 25 years. Needless to say, Socal reacted heavily and shot that down period. How dare they Is all I could think about.

Most visual inspections focus on things like broken or loose pipes, wires, muffler hangers etc. Most inspectors don't know anything about vettes much less that early C4's had and needed pre-cats on the y-pipe. Nobody would have failed inspection over that ...

I changed my front y pipe a stainless steel pipe and only regretted that the noise got definitly louder. I eventually used DEI header wrap on the new front pipe and got the noise back down to normal (whatever that was).

As an added bonus, I noticed that the header wrap completely took away all the creeks and croaks that the exhaust system used to make whenever I shut the car off. It doesn't do that anymore compared to a C5 vette which I noticed doing at the gocery store parking lot. The lady was still getting her purse etc. and I could already hear that stuff... Havent heard any C6's doing it yet :-)
They just passed a new law here. Hot Rods and replica cars are subject to smog laws and must have all the smog crap required in whatever year it was built. It applies to all kit cars. So if you buy one of those Cobras or a duece coupe rolling chassis, you have to bring it up to today's standards and pass a smog.
Old 08-07-2007, 11:00 AM
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Unfortunately California seems to be the one place where you are left with the choice of knocking out the center of the pre-cats to pass visual inspection or just live with them...I feel sorry for you.
Or leave the car as off-road only...how is that a realistic option either???
Old 08-07-2007, 11:28 AM
  #32  
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Originally Posted by Kool88vette
Your exhaust will not be optimized if you have a choke point. The stock Y pipe is 2 1/4" and not mandrel bent. The new Y pipe is 2 1/2" mandrel bent. The pipe should increase HP. The precats are 20 years old, restrictive and probably somewhat clogged. The new precats flow much better. I think the Y-pipe is the choke point in my exhaust. I have a Carsound cat and catbacks.
The "choke point" is the 3" opening at the Y. IMO increasing each side of the Y pipe by 1/4" will make no real difference. They still merge into the 3" juction. If your cats are truely clogged obviousy this will help. If not, it will just be a little more noisy, with or without cats. Been there done that.
Old 08-07-2007, 01:01 PM
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WOW!!!!!! Holy crap!!!!!!!! so if you owned a 1968 chevy vette in california, you'd have to retrofit it to be smog legal with today's standards? Unbeleivable.

Who legislated this stupid law? Was there a study done on how this would effect the car business in california?

All I can say is that I hope the sons of b__ches that passed this law get crushed emotionaly at not being able to help their kid own an older whatever car they fell in love with. Try to bring a 68 vette up to snuff and see how much that will cost in custom work.

What about enforcement" Will a **** chp ahole be able to give you a ticket for not being smog legal? How would they prove it if you're registered and have stickers already?

what a dumb law.

What california needs is a mass revolt. Everyone should register their cars but declare them as being out of state.

There is a stupid law that allows you to keep a california plate EVEN if youre out of state and you will be exempt from smog. I know this because I STILL have cali plates on my 86 vette and 92 Bronco while out living of state. I just pay the fee every year and they send me the sticker so I'll keep doing it. Everytime I get pulled over I say the car just got here and that's the end of that conversation. The cop is usually too stupid to follow up and they just get engrossed in writing the ticket for the original offense ....

I'm not against the law enforcement community but in this case, kiss my keester and go get a life ....

(NONE of this is directed at fellow forum members. I'm just peeved at yet one more frikkkin unfair law passed by ignorant people.)
Old 08-07-2007, 03:44 PM
  #34  
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Originally Posted by leefarah
WOW!!!!!! Holy crap!!!!!!!! so if you owned a 1968 chevy vette in california, you'd have to retrofit it to be smog legal with today's standards? Unbeleivable.
No, I don't think that's the case. It only applies to limited production replicas or old hot rods that have been extremely modified in appearance. It goes by the year of the engine or chassis to determine what standards have to be met.



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