DJNateGnau

HAHAHAHAHA, I knew someone would say that!

GTPsRule

Ok well then I further expect you to take off your smaller pulley, exhaust, and your intake, all of which create more emissions due to more air and fuel being burned
And for the record, the o2 sim does nothing to increase emissions. All it does is let the PCM know if the cat is bad or not. It does not perform the duties that the main pre cat o2 sensor does.

Brian MP5T

Did anyone bother to think that perhaps the engine was designed to run with backpressure and that removing the cat in theory would make the car breath easier but perhaps there is loss elsewhere (Like in the Valvetrain) that will make the "Ass Dyno" have diferent results than the "Real Dyno"

No negativity or Flaming, just an open forum for discussion...

selfinfliction

i meant to add to this that ohio is doing away with their e-checks as of next month. the reason for it is that they do absolutely no good

Drewfu$

backpressure = myth

But I'll assume you mean "scavenging" and thats only useful to naturally aspirated engines.

GTPsRule

Backpressure and its effects on scavenging is no myth, and is useful on all engines, but mainly N/A because of the usually lower dynamic compression ratios and lack of intake intake pressure to force exhaust gasses out of the cylinder. Scavening prevents reversion, which can cause a polluted air/fule mixture, which in effect will reduce power. And you dont want it too free flowing, which will cause some of the mixture to pass right through the cylinder and into the exhaust during valve overlap. Of course cam selection also plays a part in that, but tuning backpressure is also key in preventing both reversion and escaping fuel mixture.
To call it a myth when it is pure physics is kind of wacky if you ask me Just my $.02 on the subject.

Brian MP5T

Yes by Backpressure I mean the increase in effective removal of gas in a manifold and system by the use of the escape velocity of the gas by timing the manifold to match the firing sequence..

No Myth..

Ok, so I am a hypocrite and I removed my Cat, but I still have backpressure because of a 2.5" turbine in my system, On a turbo, backpressure is the devil.

On a N/A car, when you remove it, you normally do not gain more HP, you simply move it higher or lower depending on the basic engine design.

Just to clarify.. The Cobalt SS is still N/A as far as the exhaust system is concerned so Yes it is a F/I car but not on this topic...

R33P3R007

that was the point

myoshizawa819

I have tried to gut the cat but she keeps running away

Seriously, gutting the cat will produce more power.

Ohio is getting rid of e-check??? I can't wait, biggest waste of tax dollars in creation.

R33P3R007

where can you get a plug in simulator. I have seen the wire in kind and I have seen plug in ones for older cars. But not the 05+ 2.0 yet

R33P3R007

http://www.afterthoughtsauto.com/info.html says they have one, but I called like months ago and the lady was supposed to call me when they finished developing one that will work on our car. until then I am not doing it. No reason to cut the wires and splice one in if you don't have too. Now I can't get in touch with them again.

selfinfliction

yep sure did, and we fixed the backpressure issue yesterday with a method used on some types of race vehicles won't go into what it is until the exhaust is completely done. my issue is now the velocity is so fast coming out the flowmaster, it makes the stock exhaust tip rattle like a ****, so i had to order a new tip to replace it.



ebay, look aorund for reputable vendors, and then visit their website, you can contact them for specifics... if you have a 2.2L cobalt don't do it though cause it won't work you can buy them for $15~ or so

zinner

Removing your cat from your exhaust system greatly increases your emissions. Much more than just burning a little bit of extra fuel for more power.

In fact I would say that my mods cause me to run a bit leaner than stock and running leaning decreases emissions as far as VOC and CO are concerned.

Oh an if it was so bad then I think my emissions checks on my car would fail right? Since it's monitored by a high tech computer thats programmed by someone a lot more knowledgable about the subject than me. However removing your cat and placing an O2 sim in place of the secondary 02 system is defeating that emissions check, so that has to be great for the environment right? Definetly not comparing apples to apples.

You must have spent to much time over by kodak park GTP You should understand the pollution problem more than anyone else, I mean with cancer clusters and the ground water being so polluted in certain spots of monroe county.

05YELLOWSS

(hugging a tree)....goodbye tree...CHAINSAW

I use 10,000 gallons of fuel a day, I am an aircraft crew chief...

Brian MP5T

Ok, So you had to create backpressure because you got rid of a part of your car that made backpressure..

So what was the point. I really want to know, no Flames here 4 Real. I'm curious.

GTPsRule

Only thing I can guess is you inserted a cone into the exhaust after the header collector. I forgot what they were called, but I've seen them before. Other than that, I cant really think of any other way to increase velocity and decrease backpressure. Can we get a hint or two

selfinfliction

it doesn't create as much as a cat it just creates slight back pressure cause lord knows the flowmasters sure don't.


it has to do with lots of baffles (our addition) and the twist (from the race vehicle piping designs)

zinner

An article I read said that flowmasters had about the worst CFM ratings of most of the popular mufflers.

I will try to come up with a link.

Brian MP5T

"Hooah"

(US Army) A spirited cry, which can mean nearly anything positive. Short for "Heard, Understood and Acknowledged.

selfinfliction

there's 500 stories form where that word came from i was in for 6 years myself

selfinfliction

yep, but they also have 0 rasp, and on a 4cyl car with the muffler near the end, that's hard to do... without spending $800 on a borla

Brian MP5T

Still Going after 13 years..



[/threadjack]

selfinfliction

lol i was a tanker in the army too on the m1a1 heavy and commons

Brian MP5T

Leopard C2.. Try Google

n4ggs

MAD more gooder yo, fo shizzul

you gut the cat to get more power for free.... do we really have to explain anymore than that?

fin california emissions laws. ima go with a test pipe on the street and once every 2 years put the cat back on for the test.