montie98

A high flow cat is the way to go

bogus

that may be true - to a point... the cats will keep those numbers down for the entire life span of the engine.

smallblock

:rolleyes: :rolleyes:

6318

I agree with CFI-EFI...it all depends on how cheap your cat was in the first place...modern low resistance cats only take 3-4hp...old cheapies can rob as much as 10-15...I would guess factory vette's steal about 5-6...but if you haven't maximized your headers, exhaust...cat restriction won't be your bottleneck...

Gearheadotaku

I remove cats for a second reason, the amount of heat they put out. The pre-cats are close to the motor and trans, the main near the seats. By getting rid of these, the car runs much cooler. Not all cars have trouble with heat, and yes, a modern cat in good order won't affect flow much. But an old, clogged, or poorly placed cat has to go! People like us keep our cars in good running order, so the pollution is not a concern.

my .02 :smash:


[Modified by Gearheadotaku, 7:34 AM 12/26/2003]

HiRiser

I have never had a gutted cat car not pass emissions. Cats are just govt mandatred fail-safe devices for dopey people(obviously no one on this board ) who never change their oil or plugs. With LCD (lowest-common-denometer)actions like this the 95% pay for the foolishness of the 5%
But it looks like the tree hugger propoganda is working fine :jester

WardVette

Damn those free riders!

C10 JDR

I once read somewhere that the pollution caused by the manufacture of a CAT is greater than the pollution reduced by the CAT in its service life

I am cynical old and grumpy enough to believe it.

J Z06

YEp ... thats the day almost everyone ran their best at the challenge! We we're walking around like the smiling robots! It makes a big difference having a free/flow type of exhaust versus one that is capped up. :yesnod:

Gearheadotaku

haven't heard this before, but sounds resonable so...
:iagree:

NOT-MEE

Hell i just removed the precats and went with a aftermarket high flow Y pipe and cat and no mufflers .I just passed state emissins inspection on theier dyno with flying colors my car was putting out 1/4 of the emissions spec that it can and still pass.ill Post my spec sheet later this week.

TheStef

Cool to know, I had my precats gutted, one of them had broken on the inside and was ratling.

They just re welded the pre cat shut after gutting them.

I was told they are mostly for the resonnance, not as much for polution.

Mrcorvette91

Just get rid if the pre-cats and the cat...weld in their place aluminum pipe...Huge seat - of the -pants feel in power, and for the first time, she sounds like a real sports car. Dump the factory mufflers and purchase a set of aftermarket mufflers... :thumbs: Then you will not only run better, but you will sound the way a Corvette was meant to sound... :thumbs:

98NYFINESTVETTE

I did it, and did I notice a big difference in ET's and mph.

VR'92

I removed mine and put 2 straight through pipes on for $50. It has been the best/cheapest Mod I have done so far. Too bad for California people :nopity

Larrym96815

How much difference?

Aloha,
Larry

joeveto

Don't forget that the "buttometer" is monitoring both your wallet and the jar of Ben Gay. The harder the job, the longer it takes or the more it costs, the greater the "buttometer" readings. I should have gotten a full second off my ETs with the heater core change.

:iagree:

Truer words have never been spoken.

:yesnod:

darkred91

:iagree: :iagree:

kcl98

I think alot of your gain will depend on if your car has single or dual cats - dual cats flow pretty good. The factory claimed 10 horse for the dual cat L98 F-body over the single cat cars. I had a 383 TPI TransAm a few years ago that made 339 rwhp through dual random technology high flow cats. On open headers it made 346 rwhp - only 7 horse - but that's a seriously modified motor - and that measurement also included loss through the muffler. A stocker would probably only make 5 or less - unless it was a single cat car to begin with. Also, if you do it - I'd put in a straight pipe - a punched out converter may create some added turbulence in the gas flow due to changing cross-sectional area compared to the pipe - the area expands as the gas enters the hollow converter & then contracts again as it leaves the converter. That effect may hold you back from maximizing your already small gains.

KC :cool:

MyBlueC5

I have to disagree. When I had an LT1 in my late model S10 that was built, no smog pump, no cats, my CO2 readings were .02% (out of an allowable 2.2%
Hydrocarbons were at 2.2ppm (out of an allowable 220 ppm)

These motors burn SO clean that even with the stuff removed, they are cleaner than 99% of the cars from the factory.

Even the LT1 that's built in my '95 vert with cats gutted blew through the inspection...

Mark