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Running no cat

Jan 7, 2004 - 11:28 PM
Justin View Member Profile Enthusiast Joined Dec 13, '03 From Alabama Currently Offline Reputation: 1 (100%)	Tomorrow I'm going to get some custom exhaust pipe made for my celica. I was wondering how much louder it would be without cat. I am gonna have 2 1/4 in piping with no resonators and a muffler. Also, I heard that if you dont have a cat there will be a very noticable smell indicating you dont have one. Third, would it give me any hp gains since the midpipe would now be 2 1/4 Last, how easy would it be for a cop to tell that you dont have one. I live in alabama and we dont have to go through any emissions or vehicle inspections

Replies

Jan 8, 2004 - 9:44 AM

SpedToe169

Enthusiast

Joined Aug 29, '02
From Dallas, Tx
Currently Offline

Reputation: 0 (0%)

QUOTE

Instead of removing the cat, get a header.
It eliminates the cat.
then get a high flow cat and have it welded in somewhere in the piping.

That is an excellent idea.

I don't know where you're all getting this 'smell' business from. Its not going to smell if you take off the cat....have none of you ever driven a pre 1975 automobile? No cats there.

Coomer...backpressure is ALWAYS a bad thing!!

QUOTE

BACKPRESSURE = TORQUE?
An old hot-rodder's tall tale: Engines need some backpressure to work properly and make torque. That is not true. What engines need is low backpressure, but high exhaust stream velocity. A fast-moving but free-flowing gas column in the exhaust helps create a rarefaction or a negative pressure wave behind the exhaust valve as it opens. This vacuum helps scavenge the cylinder of exhaust gas faster and more thoroughly with less pumping losses. An exhaust pipe that is too big in diameter has low backpressure but lower velocity. The low velocity reduces the effectiveness of this scavenging effect, which has the greatest impact on low-end torque.

Low backpressure and high exhaust stream velocity can be achieved by running straight-through free-flowing mufflers and small pipe diameters. The only two exceptions to this are turbocharged engines and engines optimized for large amounts of nitrous oxide. Both of these devices vastly increase the exhaust gas volume and simply need larger pipes to get rid of it all.

Don't get rid of the cat, its irresponsible environmentally and won't gain you any power.

Posts in this topic

Justin Running no cat Jan 7, 2004 - 11:28 PM

FallenHero NO WE DON'T welcome to the board! If you... Jan 7, 2004 - 11:49 PM

Coomer I'd keep your cat on...you probably need it fo... Jan 7, 2004 - 11:52 PM

Phat_99CeliGT Instead of removing the cat, get a header. It elim... Jan 8, 2004 - 12:28 AM

dcgoalie312 i got my cat removed as soon as i got my car cuz i... Jan 8, 2004 - 9:28 AM

SpedToe169 QUOTE Instead of removing the cat, get a header. I... Jan 8, 2004 - 9:44 AM

Coomer QUOTE (SpedToe169 @ Jan 8, 2004 - 6:44 AM) Coomer.... Jan 8, 2004 - 1:18 PM

Justin thanks for the advice I'll be keeping my cat Jan 8, 2004 - 1:54 PM

Uppitycracker QUOTE (SpedToe169 @ Jan 8, 2004 - 7:44 AM) Don... Jan 8, 2004 - 2:13 PM

wind that rotten egg smell is the cat smell.... the cat... Jan 8, 2004 - 3:34 PM

Uppitycracker QUOTE (wind @ Jan 8, 2004 - 1:34 PM) that rotten e... Jan 8, 2004 - 3:43 PM

SpedToe169 QUOTE When racing, I'm sure it is, but when yo... Jan 8, 2004 - 5:45 PM

Justin I just got my exhaust completed a ffew hours ago a... Jan 8, 2004 - 9:31 PM

Doge The purpose of a cat is to take away all the envir... Jan 10, 2004 - 2:18 AM

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