Tiger Shark

If I were to ditch my pre-cats (pups), would I still be considered street legal in Texas?
I heard that the pre-cats were added only to allow the C5 to pass emissions requirements in California.

1) Is this true?

2) Without the pups, would I still pass emissions testing in Texas

3) What is the definition of street legal (with regards to the exhaust system)? Are you supposed to not modify any of your factory-installed exhaust system and if you do, you're not legal regardless of whether or not you meet current (in your state) emissions requirements?

If I replaced them, it would be by installing TPIS long tube headers thereby replacing the area of pipe previously occupied by the pups.

Thanks.


[Modified by targac5, 4:25 PM 9/4/2001]

65Z01

I'm not sure about C5, but Random Tech. makes a 3-stage hi-flow cat which can be used to replace the stock cat and the two pre-cats on a C4. It's smog legal in 49 states. You might check their site for C5 cats.

Anything after the cat is legal so long as it meets noise constraints.

wsaracen

i believe they have to be 18 to be legal. :jester

Tiger Shark

On the 2002 Z06, they removed the pre cats and improved the emissions control somewhere else. If it was done in the Z06 cats, I wonder if I could get a pair of those to replace my regular cats if I really still wanted to be considered street legal.

CP

There's no physical check for a converter or converters. You only have to pass the tailpipe probe!

MitchAlsup

Why are the pre-CATs called PUPs and not called Kitties?

97C5ENVY

Anyone feel free to correct me if i'm wrong.........but i was under the impression that any "Emmission Controlling Device" (eg. smog pump, pre-cats, cats, EGR stuff, etc) that was placed/installed by the manufacturer had to remain in place to be "legal".

However, i can't see why anyone would want to check if the pre-cats were in place or not........and never heard of anyone actually doing so either.

Tiger Shark

Okay, good answers above. Thanks.

So does anyone know if the pre-cats were simply added to allow the C5 to pass CA emissions requrements.

Would my C5 still pass Texas emissions testing without the pre-cats?

Gracias,
TargaC5

Tiger Shark

One more additional question to the above...

What exactly is the difference between the 2002 Coupe/Covertible exhaust and the 2002 Z06 exhaust that makes the Z06 not require the pups?

RajunCajun2001

You're right. It is illegal to modify emissions equipment. If you're in Dallas County, you will have to undergo emissions testing...without the pre-cats, you may or may not pass. Why run the risk of getting caught for minimal to zero hp gains? Some posts have actually reported low end hp and tq loss by removing pre-cats.

I don't remember the fines, but they were in the thousands. BUT, you'd have to get caught first. :cheers:


[Modified by RajunCajun2001, 4:38 PM 9/4/2001]

Tiger Shark

I thought you get substantial gains from ditching the pre-cats. Isn't that why Corvette engineers did away with the pre-cats on the 2002 Z06?

The main C5 cats are already super efficient and very little would be gained by doing away with them, but what about the pups?

Would I be able to pass emissions testing in Texas without the pups?

Thanks.



[Modified by targac5, 5:12 PM 9/4/2001]

DAP

Pre-cats, Pup-cats, Pre-heaters-they have lots of names (I called them Quad-cats on 86 and later V-8 'stangs).

I think their main and only purpose is to provide a higher level of "scrubbing" to assist the main cats before they come online temperature-wise during the vehicles warmup.

Once the system is up to temp, I believe the forward converters become of little use.

Removal of the pups may result in a slight loss off low rpm torque, which should be offset by the power gains. Allowing the '01's larger manifold to scavenge a little better...maybe 5-10 horsepower from the pre cats above 5K. There is only a few more horses to gain after that by dumping the back cats.

DAP

OOPS, sorry. You should be able to pass the tests, as long as your vehicle is warmed up while it is sitting there (which it will be thanks to Chevy's deliberate decision to turn the fans on at 225-230 degrees!) :mad

Tiger Shark

Heh heh, after next week, my fans will be turning on just a little bit sooner.

Thanks for the input.

DAP

Gee, you wonder why the LS1 has a 190 thermo, and the fans kick on at 225-230. Can you say "emissions" :p:

In 75 degree weather, I saw 186-stock thermo DIC-at 40+. It would lead one to beleive that the engine was designed to operate between 180-200, and not 230...Hmmmmm :chevy

Tiger Shark

ttt

corvette_karl

I've heard rumors that the car runs so clean that it will usually pass emissions even in CA w/o the precats.

In Texas I don't think you'll have a problem. My LT-1 in my '97 Ram Air sailed through with flying colors.

Get the engine good and warm before you take it in though. It runs cleaner when warm.

WhiteDiamond

I know from toying with my TransAm and MTI heads/cam mods to it that these motors will pass emissions very well with even larger cams in them. I used high flow cats on my car as well, and still had no issues.

But, as mentioned, removal of any factory provided emissions device is a federal offence. It is also true that removing the "pup" cats could show very little difference in your actual emissions test, but remember that GM does much more extensive emissions testing on drivetrains and measures cold start emissions as well(most people don't drag their car to the station on a trailor and then do a cold start emissions test, that is when the pups would help you out). The "pup" cats are easier to "light" off at lower temps, allowing the vehicle to enter low emission(LEV) status in 2001. GM said they where definately a restriction in the 2002 Z06 Corvette release info.

Todd

C5Longhorn

I think you could remove the Pre cats with no problem. They didn't even come on the '97-'00 cars and they have no problem.

RajunCajun2001

TargaC5, I think you'd pass emissions testing, but you wouldn't be legal. Removing them (regardless of emissions testing) is illegal, but there is no real mechanism to catch you other than emissions testing. But they'd have to look hard to find them missing, know enough about vettes to realize something's missing, and care enough to report you.

I asked around, and the fine for tampering with emissions equipment is over $10K and it is a Federal crime. But like I said, I doubt you'd ever get caught unless you fail emissions testing and they inspect under your car. Then again, they could change the laws and inspect under the car, and then you'd have to put them back on for sure.

Sounds like a real risk given the minimal if any hp/tq gains IMO.


[Modified by RajunCajun2001, 2:03 PM 9/5/2001]


[Modified by RajunCajun2001, 2:04 PM 9/5/2001]