Cats Cut Out=power/mileage Loss=myth

[silveradoguy98]

Well, i cut my cats out last night. I didnt feeel any power loss whatsoever. Too soon to tell if i lost any mileage or not, but i'm guessin its gonna be the same. The check engine light is on but i went to http://www.afterthoughtsauto.com/o2sim.html and bought some o2 sims which wil arrive in a couple of days. That should get rid of the light. So if there's any of you guys that are skeptical about cuttin your cats out, don't listen to anyone unless they've actually done it like me. I've got 2" true duals ran back to two 14" glasspacks. Truck never ran better...

[Koots]

Cutting the cat out or gutting it will not decrease power, but it will not significantly add to it either. Most cats don't actually limit horsepower enough to care until you start pushing the horsepower on your engine to a higher level. Plus most peoples cats are close to being clogged and to get rid of them seems like a whole new jump in performance.
But i'm glad things are workin out for the better, Have fun with your improved truck exhaust.

[Chevyman247]

you just increased your exaust velocity, good job.

I dont have cats, runs great sounds better too.

You noticed sound differnce?

[Koots]

Not that is sounds better without it. it just sounds louder. if you have a crappy sounding engine (like my old 88 cavalier) than you now have a crappy and loud sounding car. you must have had a nice sounding engine anyway. I just got rid of the cat on my Civic cuz i got a header and mid-pipe. the cat is actually located in the manifold itself so i have no choice but to be illegal hehehe. Can't wait to get it running.

[Just G]

Interesting article on cats, since many say that by removing them, the environment is adversely affected.



E.P.A. Says Catalytic Converter Is
Growing Cause of Global Warming
By Matthew L. Wald
Copyright 1998 The New York Times
May 29, 1998

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WASHINGTON -- The catalytic converter, an invention that has sharply reduced smog from cars, has now become a significant and growing cause of global warming, according to the Environmental Protection Agency.

Hailed as a miracle by Detroit automakers even today, catalytic converters have been reducing smog for 20 years. The converters break down compounds of nitrogen and oxygen from car exhaust that can combine with hydrocarbons, also from cars, and be cooked by sunlight into smog.

But researchers have suspected for years that the converters sometimes rearrange the nitrogen-oxygen compounds to form nitrous oxide, known as laughing gas. And nitrous oxide is a potent greenhouse gas, more than 300 times more potent than carbon dioxide, the most common of the gases, that is warming the atmosphere, according to experts.

This spring, the EPA published a study estimating that nitrous oxide now comprises about 7.2 percent of the gases that cause global warming. Cars and trucks, most fitted with catalytic converters, produce nearly half of that nitrous oxide, the study said. (Other sources of nitrous oxide include everything from nitrogen-based fertilizer to manure from farm animals.)

The EPA study also showed that nitrous oxide is one of a few gases for which emissions are increasing rapidly. Collectively known as greenhouse gases, they trap heat in the earth's atmosphere.

The increase in nitrous oxide, the study notes, stems from the growth in the number of miles traveled by cars that have catalytic converters. And the problem has worsened as improvements in catalytic converters, changes that have eliminated more of the nitrogen-oxygen compounds that cause smog, have conversely produced more nitrous oxide.

Wylie J. Barbour, an EPA official who worked on the recently published inventory, said that the problem created by the converter is classic. "You've got people trying to solve one problem, and as is not uncommon, they've created another."

Nitrous oxide, or N2O, is not regulated because the Clean Air Act was written in 1970 to control smog, not global warming. And no regulations exist to control gases that are believed to cause global warming.

The United States and the other industrialized nations agreed in Kyoto, Japan, last December to lower emissions of greenhouse gases to 5 percent below 1990 levels, over the next 10 to 15 years, but the agreement has not been approved by the Senate, and no implementing rules have been written.

"This hadn't really been on people's radar screen until climate change started becoming an issue," said one EPA official involved in reducing pollution from cars, who asked not to be identified by name.

The EPA has not proposed a solution at this point, and is seeking public comment on its study. Auto industry experts say they could solve the problem by tinkering with the catalytic converter, but some environmentalists suggest that the growing production of nitrous oxide is yet another reason to move away from gasoline-powered cars. The EPA's study estimated that nitrous oxide may represent about one-sixth of the global warming effect that results from gasoline use.

"It's like, clean is not green," said Sheila Lynch, executive director of the Northeast Alternative Vehicle Coalition, a public-private partnership that encourages non-traditional power sources.

Another expert, Christopher S. Weaver, an engineering consultant who wrote a study on the subject for the environmental agency, said, "We haven't cared enough to establish standards."




Precisely how much nitrous oxide the converters produce remains an issue. A report used by the EPA in preparing its greenhouse gas study, calculated that a car with a fuel economy of about 19 miles a gallon would produce .27 grams of nitrous oxide per mile. That represents an amount that is about one-third the limit of emissions for nitrogen oxide, the chemicals causing smog.

Steven H. Cadle, a research scientist at General Motors, said, "it's a huge number." In contrast, an older car without a catalytic converter produces much larger amounts of nitrogen oxides, but only about a tenth as much nitrous oxide, the greenhouse gas.

The EPA calculated that production of nitrous oxide from vehicles rose by nearly 50 percent between 1990 and 1996 as older cars without converters have neared extinction. Using a standard unit of measure for global warming gases, millions of metric tons of carbon equivalent, nitrous oxide emissions rose to 54.7 million tons from 36.7 million during those years, the study said.

The contradictory impact of the converter has not been lost on environmental officials or industry experts, who continue to debate not only the extent of the growing problem as well as how to reduce the emissions in future years.

Ned Sullivan, the head of the Maine Department of Environmental Protection, said the converter problem requires a "comprehensive" response. "This specific issue fits into a broader context that our regulatory system has tended to deal with pollutants on an individual, rather than a comprehensive, basis," he said.

He and others favor moving away from today's typical car design, a big gasoline engine driving the wheels, to electric cars. Maine would like electric cars. Another solution is hybrid cars, which use small, efficient engines running on gasoline to help turn the wheels and to charge batteries for electric motors that also run the wheels. Those have much higher fuel economy, and thus lower greenhouse gas emissions.

Car industry experts, however, favor less drastic changes. They propose cutting nitrous oxide production by adjusting catalytic converters in future models. They suspect that the gas is produced when the converter is warming up, and believe the converters could be redesigned to reach optimum temperature faster. That would also help them destroy other pollutants better.

Weaver said that measurements on more kinds of cars and light trucks would be needed to be certain about the size of the problem. But Weaver said, "It is quite clear that you produce nitrous oxide in a catalyst, in some circumstances."

At the Union of Concerned Scientists, an environmental group, an expert on transportation pollution, Roland Hwang, said, "We can't be pushing forward trying to reduce smog while making the global warming problem worse; we can't have programs that undercut each other." He said this was evidence that the transportation system would have to use something besides gasoline.

Cadle, of General Motors would not go that far. But, he said, "You have to be holistic and try and look at everything, which is obviously difficult."



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[silveradoguy98]

you just increased your exaust velocity, good job.

I dont have cats, runs great sounds better too.

You noticed sound differnce?
Hell yeah i noticed a sound difference. In my opinion, there is a night and day difference between a truck with cats and a truck without. I've got some before and after video sound clips that i will post once i fix my computer.

[Pauly]

Your Vortec 350 has dual 1 7/8" headpipes which crimp down even smaller in teh bends. if youw ant soem real power gains, replace the stock 17/8" headpipes with teh larger 2 1/4" headpipes from the 3/4 ton Vortec 350 truck. OR get some custom headpipes made up like I did. (dual 2 1/2")

The Vortec 350 cats arent the restriction, they actually flow very well in stock form. Its teh pipes that feed the cats that are therestriction. Great for off idle.low rpm torque torque, but crappy for power.

The money you spent on O2 simulators could have been used to get a full PCM tune, in which you can also have the post cat O2 sensors disabled. Plus you could have gotten TM disabled and gotten firmer shifting, top speed limiter disabled, better shiftpoints, the list goes on and on. In todays age of PCM tuning, O2 sims have become obsolete.

I cut off my cats once, and my Vortec 350 lost off idle torque, but I gained a hp or 2 up top.

Your new exhaust shoudl flow better than teh crappy dual in single out muffler.

Good to hear your happy with your truck. I bet it sounds great.

peace
Hog

[bradthomashines]

just curious is it true that cutting the cats enhances wear on engine by making the engine run rich or lean? I always heard that on the newer trucks they are tuned to function with the cats and cutting them out isnt good at all for the engine? Thats the only thing stopping me from cutting my out!

[Chevyman247]

your sig pic is too big, make it smaller like mine.

They increase backpressure and its harder form an engine to run with more back pressure, the less the better. I dont know about the computer stuff. someone else can help you on that.

[bradthomashines]

ok so from a back pressure stand point they hurt the engine? so it would be better to cut cats and run a muffler as opposed to leaving the cats and cutting the mufflers? and sorry bout the sig is it better now?

[Chevyman247]

sig and truck looks great!

They dont hurt the engine, they just make it harder for the engine to breath, so in the end the motor is working harder to pump exaust out. Its just easier on the enigine in general which in turn extends motor life. I dont run cats with my dual flow 44s and it sounds awesome! They also decrease sound.

[Hilljohnston]

So if i run no cats with true dual Dynomax bullets with 2 1/2 inch pipe with no crossovers at all it will run good? (2000 GMC Sierra w/ 5.3)

[96thebossgrnchv]

anybody actually dyno tested, with cats and without cats?

[phatchevy06]

anybody actually dyno tested, with cats and without cats?
I've seen it go both ways on different vehicles. Losing or gaining. This is why I'm a strong believer in high-flow cats. Maganaflow’s high-flows were proven to flow ALMOST the same amount of CFM as not having any at all...without the "potential" downside of not having any :wink:

[4ws f 7]

Like someone else said the PCM needs to know what has been done!

[Koots]

http://www.importtuner.com/features/0610impp_catalytic_converter_removal/

I've posted this link before but i cannot find it so here it is again.

This is an article pertaining to Honda Civic Engines, which don't gain a whole lot from simple bolt-ons but the information is there. I say if you did this with your truck you wouldn't gain more than 5-6 horses based on the honda info. But there are more factors involved between the Hondas and GM engine and vehicles, but it is a reciprocating internal combustion engine and will relate to our motors. Hope this article helps.

[bradthomashines]

anybody looking to be louder with a good tone for cheap just crawl underneath and cut the exhaust off completely after the stock Y pipe just cut right after the first hanger i did mine yesterday and i like the way it sounds I just wish it was a lil louder. and Thanks Chevyman247

[96thebossgrnchv]

lol i cut my exhaust off for acouple weeks, sounded badass at first, then got annoying as hell

[big burby]

The skinny on cats is that they work at egt's of 600 degrees or better proper running engine never maintains this so if engine working right they see no use. However as stated the new honeycomb or screen type produce litle to no increased back pressure although they will increasenoise slightly. cut em out won't hurt the truck but your gains are negligeble a proper muffler and correctly sized exhaust tubing duals should be no less than 2.25 and no larger than 2.5 on street engines of 200 400 horsepower include an x pipe will give you gains on an exhaust however most tools put open pipes on a un cammed engine and seee half the fuel charge shoot strait out the pipes. engines is an air pump ladies and germs make it efficient makes power not silly fads.