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I have a CAT in the I-Pipe.

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Old 11-16-2005, 08:27 PM
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Lightbulb I have a CAT in the I-Pipe.

I recently saw my Y-pipe and noticed it has been banged up after a year or so of driving. It needs replacing and I will go the dual route when I feel comfortable. In the mean time, I might as well ask...

I have Hooker long tubes, going into a mufflex off road y. And In the I-pipe I have 1 cat installed. Now I originally wanted two in the mufflex, but the exhaust shop told me they didnt know if they could fit 2 carsound cats (which I bought previously) into the mufflex without it not being properly sealed. And since it was a nice setup, they didnt want to go messing it up. Well, now that it is messed up, do you think that 1 cat in the I-pipe is restrictive? its 3" in/out as is the y and catback is all 3". But I just wanted to know from the mathmaticians in here, if having that cat in that part of the exhaust would be worse than 2 in the proper spots of the Y.
Old 11-16-2005, 10:06 PM
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My question is why? If you have it on for emissions, a) it's not doing anything because they need lots of heat to work and b) you won't pass smog becuase it's not in the factory location.

The only reason I could see is to cut out some rasp, but I would think that an XR1 or a Bullet would be less restrictive and better suited for the job.
Old 11-16-2005, 10:22 PM
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Originally Posted by Zeus
My question is why? If you have it on for emissions, a) it's not doing anything because they need lots of heat to work and b) you won't pass smog becuase it's not in the factory location.

The only reason I could see is to cut out some rasp, but I would think that an XR1 or a Bullet would be less restrictive and better suited for the job.

it was for the smell.
Old 11-17-2005, 12:13 AM
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Yes, it is restrictive. One high flow cat in the I pipe is more restrictive than two stock cats in the y-pipe.
Old 11-17-2005, 06:07 AM
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Originally Posted by AKIRA
I recently saw my Y-pipe and noticed it has been banged up after a year or so of driving. It needs replacing and I will go the dual route when I feel comfortable. In the mean time, I might as well ask...

I have Hooker long tubes, going into a mufflex off road y. And In the I-pipe I have 1 cat installed. Now I originally wanted two in the mufflex, but the exhaust shop told me they didnt know if they could fit 2 carsound cats (which I bought previously) into the mufflex without it not being properly sealed. And since it was a nice setup, they didnt want to go messing it up. Well, now that it is messed up, do you think that 1 cat in the I-pipe is restrictive? its 3" in/out as is the y and catback is all 3". But I just wanted to know from the mathmaticians in here, if having that cat in that part of the exhaust would be worse than 2 in the proper spots of the Y.
It's all a matter of flow rate, so yes it is VERY restrctive. It will be helping emmisions as heat is not the primary source of lower emissions, it is a chemical reaction of the exhaust gases flowing over the cat innerds, usually a ceramic block.

Use this as a guide, 2.2cfm for every 1hp.

I have no idea what you CAT flows at, but I doubt it's startling. At best it is probably 400cfm, but would well be below 200cfm. If you assume a stock engine produces 345bhp.

345 x 2.2 = 759

Your minimal flow rate on a stock engine should be 759cfm. Even the best metal matrix CATS only flow at around 550cfm so yes it is very restrictive.

If you have one CAT per exhaust/cylinder bank it only has to deal with half the exhaust gas and half the flow rate. So on a stock engine with two CATS they only need to flow 380cfm which is pretty doable my many aftermarket CATS.
Old 11-17-2005, 10:01 AM
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Originally Posted by AKIRA
it was for the smell.
got'cha
Old 11-17-2005, 10:18 AM
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Originally Posted by 300bhp/ton
It's all a matter of flow rate, so yes it is VERY restrctive. It will be helping emmisions as heat is not the primary source of lower emissions, it is a chemical reaction of the exhaust gases flowing over the cat innerds, usually a ceramic block.

Use this as a guide, 2.2cfm for every 1hp.

I have no idea what you CAT flows at, but I doubt it's startling. At best it is probably 400cfm, but would well be below 200cfm. If you assume a stock engine produces 345bhp.

345 x 2.2 = 759

Your minimal flow rate on a stock engine should be 759cfm. Even the best metal matrix CATS only flow at around 550cfm so yes it is very restrictive.

If you have one CAT per exhaust/cylinder bank it only has to deal with half the exhaust gas and half the flow rate. So on a stock engine with two CATS they only need to flow 380cfm which is pretty doable my many aftermarket CATS.
Then its settled. For the time being, Ill see if someone I know can take it out and put in a pipe.

Do you think this cat is used up? Or can it be recycled? Remember I have 2 carsounds (1 in garage, 1 in I-pipe). And when I come around to getting someones true dual system, I want to put these in. If I can recycle it I will.




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