Keithr726

By testpipe I mean straight pipe as in no cat in the middle of the pipe. Lindsey and speedforce both make exhaust systems with a clamp on cat and clap on straight pipe. This is a much better idea because you'd no longer have to remove the nuts from the downpipe.

333pg333

Well my plan is to get a removable Cat which I guess is what you call a test pipe.
Assuming that you have the Cat in and pass the 'test'?
Couple of V bands either side and in / out too easy!

This will be 4" Cat-back. Sound good?

evil 944t

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.

Geneqco

The problem for us is not visual inspection but "sniffer". As for "switching" to do a test, I've heard they can just come up behind you and "sniff". Sort of sounds like the animal kingdom!

evil 944t

Hmm, I see. I thought it was a visual thing. Around here, They just set up a time for you to go to inspection. They make it very easy. If you live far enough from the city(Chicago) you don't ever have to go.

RPHARRIS

A not so commonly known fact is that the common "oxidation catalyst" causes our cars to expel more CO2 than they would with a straight pipe. On my California smog certificate, one of the few things they do not limit is CO2 concentration. It's very interesting how the cause is lost somewhere in the the legislative/bureaucratic process. Running a straight pipe increases carbon monoxide and "smog" (NOx) pollution, however it does reduce greenhouse gas emissions.

I learned a ridiculous amount about this stuff when I had to deal with California smog this past summer.

333pg333

No they actually have to do something rather than pass a visual test. If they suspect your car has been modified they can take you to be tested there and then. Something tells me that a 4" exhaust and imitating a flame thrower is going to alert them, so I think by sacrificing a bit of power on the road and having straight through for the track should be the best of both worlds. There seems to be many viewpoints on the efficiency and effectiveness of Cats too, and their potential to rob power. Still better than having a $25k fine and car impounded.

Geneqco

Yeah, we don't have any automatic testing... it's just if they send you due to mods, or you want to voluntarily have testing due to mods, or get caught by a sniffer.

CO, NOx and HCO are very harmful whereas we encounter CO2 every time we exhale.

seattle951

Running 16 PSI boost and a Lindsey Racing stage II MAF and no cat, I ran 307 RWHP. After upgrading the MAF head to a better unit and adding a Lindsey Racing high flow cat, I ran 311 RWHP at 15 PSI. Both runs were done on the same dyno.

Although it is hard to separate the MAF impact from the cat impact, my guess is that adding the Cat made very little difference.

seattle951

Nitrous Oxide is a green house gas and is more effective at trapping heat than Carbon Dioxide. Therefore it is worse than CO2. Carbon Monoxide also contributes to global working. Below is some info from Wikipedia.

GWP = Global Warming Potential

Examples of the atmospheric lifetime and GWP for several greenhouse gases include:

- CO2 has a variable atmospheric lifetime, and cannot be specified precisely. Recent work indicates that recovery from a large input of atmospheric CO2 from burning fossil fuels will result in an effective lifetime of tens of thousands of years. Carbon dioxide is defined to have a GWP of 1 over all time periods.

- Methane has an atmospheric lifetime of 12 ± 3 years and a GWP of 62 over 20 years, 23 over 100 years and 7 over 500 years. The decrease in GWP associated with longer times is associated with the fact that the methane is degraded to water and CO2 by chemical reactions in the atmosphere.

- Nitrous oxide has an atmospheric lifetime of 120 years and a GWP of 296 over 100 years.

- CFC-12 has an atmospheric lifetime of 100 years and a GWP(100) of 10600.

- HCFC-22 has an atmospheric lifetime of 12.1 years and a GWP(100) of 1700.

- Tetrafluoromethane has an atmospheric lifetime of 50,000 years and a GWP(100) of 5700.

- Sulfur hexafluoride has an atmospheric lifetime of 3,200 years and a GWP(100) of 22000.

"Carbon monoxide has an indirect radiative effect by elevating concentrations of methane and tropospheric ozone through scavenging of atmospheric constituents (e.g., the hydroxyl radical, OH) that would otherwise destroy them. Carbon monoxide is created when carbon-containing fuels are burned incompletely. Through natural processes in the atmosphere, it is eventually oxidized to carbon dioxide. Carbon monoxide has an atmospheric lifetime of only a few months and as a consequence is spatially more variable than longer-lived gases."

Source: Wikipeida

RPHARRIS

Damn! Now I don't feel so smug spitting flames at all these Priuses (...wtf is the plural of Prius anyway?)

I guess now that I know better I need to go cat shopping.

Geneqco

Pri-i?

S2cab

Palm Beach County used to have emmissions testing. They did a visual for a cat, but I always suspected they profiled. Back when I had the NX2000, I had a factory cat with a Hot Shot header & CAI, & a Borla cat-back. It was a very discreet system. Not very loud at all. They use a mirror to see if a cat is present. I was asked to have the car run on the rollers, like a dyno w/o the computer, & have the tailpipe sniffed. I suspect that was to find out if the cat was gutted & a straight pipe welded inside. It wasn't very loud. That should have been the first clue the cat was in place. It did fail the test. There was a carbon clogged air injection diaphram that I had to clean out, but it was borderline. I retested after the fix, & all was fine. As a side note, the county employee almost wrecked my car on the rollers. He almost lost it when it started to go sideways during the test. That would have been interesting.

333pg333

Prissys??

PEvans

Any specific brand or source recommenations for a "quality" catalyst??