i have no resonator and i need to cut my cat, what should i do with exhaust? [Archive] - GrandAmGT.com Forum

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surfermatt95
05-30-2012, 04:41 PM
i have the resonator in my room, the cat is clogged, i want a mean and growl of exhaust but not enough noise to have people look at me like an idiot, after i take the cat off should i just put on a universal cat and just put a pipe where the resonator goes? what do you think?

AaronGTR
05-30-2012, 05:27 PM
The muffler is going to make more difference than anything. If you go without a cat though it will sound like a chainsaw, so I would definitely get a universal high flow cat. Resonator or no resonator is up to you. I've gone with and without, and didn't notice a huge difference, but it may depend on what muffler you have.

[ChaosweaveR]
05-30-2012, 05:54 PM
If you don't have an OEM style cat, you'll be stuck with the P0420 code on.

Running without a cat on a street car is just stupid. Run a good muffler and resonator setup.

surfermatt95
05-30-2012, 05:57 PM
The muffler is going to make more difference than anything. If you go without a cat though it will sound like a chainsaw, so I would definitely get a universal high flow cat. Resonator or no resonator is up to you. I've gone with and without, and didn't notice a huge difference, but it may depend on what muffler you have.


should i put the old resonator back on though? any cons or pros to having it on or off

locoman99
05-30-2012, 06:34 PM
sorry, we don't give stupid, illegal advice on this website...

[ChaosweaveR]
05-30-2012, 07:11 PM
It's not a racecar, and it's not boosted. Getting rid of the cat on a stock GA has no beneficial results, other than cause the car to run more rich, smell bad and throw codes.

locoman99
05-30-2012, 07:20 PM
or incorrect technical advice either...

[ChaosweaveR]
05-30-2012, 07:28 PM
How would it it be cheaper and "less complex"? The LA1 isn't some carb'd Chevy 350 small block in a Nova, you eliminate the cat, resonator and muffler, you get rid of the back pressure in the exhaust. For an N/A setup, no back pressure = loss of power.

Like I said, it's not a racecar, getting rid of the cat only nets you a 1HP gain. It's not worth getting rid of. Just because you can, doesn't mean you should.

locoman99
05-30-2012, 07:59 PM
cats don't cost $300...

[ChaosweaveR]
05-30-2012, 08:04 PM
The fact that you say that an N/A setup doesn't need back pressure shows me your lack of knowledge.

1HP, do you honestly think you're going to feel that gain? Seriously?

Again, it's not a racecar, there's no need to delete the cat on a street car.

FromTheInside
05-30-2012, 08:11 PM
You want your car to smell like rotten egg farts? Your new converter will ideally not go bad for many many years as long as you take care of the engine. If you don't run on bad head gaskets, spark plugs, injectors, etc. for extended periods of time, it should be fine. My 99 has 184,000 miles on it and the converter is perfectly fine. Why? I make sure that I tackle every problem as soon as I see a symptom. Otherwise, I keep up on my preventative maintenance.

I think you (OP) should get a good sounding (not fart can) muffler and/or resonator and replace your converter. You will be doing the environment good, make your car operate as intended, and not have a check engine light and have to deal with clearing a code 45 minutes before getting your car inspected.

locoman99
05-30-2012, 08:33 PM
irrelevant to thread.

FromTheInside
05-30-2012, 08:43 PM
When did he say that it increases max hp?

locoman99
05-30-2012, 08:53 PM
same as #1.

locoman99
05-30-2012, 09:02 PM
irrelevant to thread.

FromTheInside
05-30-2012, 09:07 PM
Okay. I agree with you that it will be cheaper in the short term. The lack of back pressure may make more power but I do not know. However, will the engine run properly without the back pressure? The mixture is created and the ignition is timed assuming a certain back pressure inside of the exhaust system. I do not know the effects but I wonder if it could hinder operation in some way or cause a later problem.

Good for you if you can get away with it but in my personal opinion, I would not do it both for the environmental factor and the annoyance of the SES light and getting an inspection.

[ChaosweaveR]
05-30-2012, 09:38 PM
Okay. I agree with you that it will be cheaper in the short term. The lack of back pressure may make more power but I do not know. However, will the engine run properly without the back pressure? The mixture is created and the ignition is timed assuming a certain back pressure inside of the exhaust system. I do not know the effects but I wonder if it could hinder operation in some way or cause a later problem.

Good for you if you can get away with it but in my personal opinion, I would not do it both for the environmental factor and the annoyance of the SES light and getting an inspection.

Glad to see I'm not the only one with some common sense here.

Also: no back pressure = loss of all low end torque.

locoman99
05-30-2012, 09:49 PM
;1178771']Glad to see I'm not the only one with some common sense here.

Also: no back pressure = loss of all low end torque.

He said that he doesnt know, which is what you should be saying. And yes it will, just like almost every other mod push the t.c. Up the powerband. But we are talking just the cat, so the effectwill be minimal

[ChaosweaveR]
05-30-2012, 09:51 PM
also not relevant.

locoman99
05-30-2012, 10:11 PM
not relevant

jd99gagt
05-31-2012, 11:04 AM
what do you need to make you car run normal w/o a cat. Is there anyway to keep the pcm stuck on the mode it's in until operating temperature. what about o2 sensor/readings?

chris_gt_74
05-31-2012, 01:41 PM
what do you need to make you car run normal w/o a cat. Is there anyway to keep the pcm stuck on the mode it's in until operating temperature. what about o2 sensor/readings?

You have to disable rear o2 codes with a programmer but I think that's about it if it's all stock. I think a high flow is better than no cat just for emissions and being able to legally drive your car on the highway's.

AaronGTR
05-31-2012, 06:30 PM
and be cheaper, less complex and make better power...gonna throw a code with an aftermarket cat anyway...your gonna need a tune anyhow if you do much exhaust work.


You have no idea what you are talking about.

The HP difference on an NA car will be 1hp or less. You will NOT necessarily throw a code with an aftermarket cat versus an OEM (mine never did). And you will NOT need tuning with exhaust work. You will always make more power with tuning, but it's not required.

You also forget that running without a cat will make the car smell and sound like sh!t. lol And also a cat won't cost $300 dollars. This would be a pretty good size cat for a performance exhaust on a grand am. http://www.summitracing.com/parts/MPE-94006/ $74. Stays legal, sounds better, smells better, better for the environment. I see no downsides.

AaronGTR
05-31-2012, 06:48 PM
Also both you guys should stop arguing about power and back pressure. Neither one of you sounds like you really understand the concept. :rolleyes:

FYI, it really has nothing to do with back pressure or no back pressure. That is a side effect. What is important is exhaust velocity. Smaller piping = higher velocity, but more back pressure. That will make better low end torque because the speed of the gas stays higher at lower rpm so the gas wants to keep moving, but at higher rpm and flows the engine has pumping loss from trying to force more gas through a small pipe, so peak power is lower. That is a lower power band setup.

Larger exhaust piping will allow more flow with less resistance at higher rpm which equals higher peak power, but the gas velocity slows down at lower rpm, so there are pumping loss at low speed from the engine having to push more to keep the gas moving, so you lose low end torque. This shifts the power band higher.

Ideally if you can keep the piping size small but design it to reduce the internal resistance, you can increase the flow (to a degree) AND keep the torque up. Methods to do this would include using mandrel bends instead of crush bends for uniform pipe diameter, using smaller degree bends such as 30 degrees vs 45 degrees for less direction change, and making the smoothest joints and/or shortest exhaust system possible. You can also do this with a small increase in piping diameter for higher peak power with no loss or minimal loss in low end gas velocity. The trick is picking the right design and pipe diameter for the engine design, rpm range, and power level.

locoman99
05-31-2012, 07:29 PM
[QUOTE=AaronGTR;1178847]Also both you guys should stop arguing about power and back pressure. Neither one of you sounds like you really understand the concept. :rolleyes:

FYI, it really has nothing to do with back pressure or no back pressure. That is a side effect. What is important is exhaust velocity. Smaller piping = higher velocity, but more back pressure. That will make better low end torque because the speed of the gas stays higher at lower rpm so the gas wants to keep moving, but at higher rpm and flows the engine has pumping loss from trying to force more gas through a small pipe, so peak power is lower. That is a lower power band setup.

Larger exhaust piping will allow more flow with less resistance at higher rpm which equals higher peak power, but the gas velocity slows down at lower rpm, so there are pumping loss at low speed from the engine having to push more to keep the gas moving, so you lose low end torque. This shifts the power band higher.

Ideally if you can keep the piping size small but design it to reduce the internal resistance, you can increase the flow (to a degree) AND keep the torque up. Methods to do this would include using mandrel bends instead of crush bends for uniform pipe diameter, using smaller degree bends such as 30 degrees vs 45 degrees for less direction change, and making the smoothest joints and/or shortest exhaust system possible. You can also do this with a small increase in piping diameter for higher peak power with no loss or minimal loss in low end gas velocity. The trick is picking the right design and pipe diameter for the engine design, rpm range, and power level.[/QUOTE

I have a cat on my car,btw

in all practical terms the only place were an exhaust can be truly " tuned" is the design of the headers and collecters. I agree that no cat vs hiflow cat is almost zero in terms of power and there are practical benefits to having one.
I disagreed with chris when he starts calling people stupid and makes up things like an engine needs backpressure.

[ChaosweaveR]
05-31-2012, 07:35 PM
He just pisses me off. lol

But my point remains, eliminating a cat on a street car is stupid and pointless.

[ChaosweaveR]
05-31-2012, 07:42 PM
not relevant.

AaronGTR
05-31-2012, 07:43 PM
in all practical terms the only place were an exhaust can be truly " tuned" is the design of the headers and collecters. I agree that no cat vs hiflow cat is almost zero in terms of power and there are practical benefits to having one.



Again, this just shows your lack of knowledge on the subject. You can "tune" the performance of the exhaust from the cylinder head port all the way to the exhaust tip. Not just in the headers. And there are many practical reasons for having a cat. I just listed all of them.

locoman99
05-31-2012, 08:23 PM
Again, this just shows your lack of knowledge on the subject. You can "tune" the performance of the exhaust from the cylinder head port all the way to the exhaust tip. Not just in the headers. And there are many practical reasons for having a cat. I just listed all of them.

After the collecter it is just backpressure. Once pulses are merged any scavinging effect is lost and gasses are cooling (expanding) and slowing down. Any "tuning" effect after the collecter is only the effect of backpressure on the effecincy of the engine and the corresponding "flattening" of the torque curve on the powerband. Period.

AaronGTR
05-31-2012, 09:52 PM
After the collecter it is just backpressure. Once pulses are merged any scavinging effect is lost and gasses are cooling (expanding) and slowing down. Any "tuning" effect after the collecter is only the effect of backpressure on the effecincy of the engine and the corresponding "flattening" of the torque curve on the powerband. Period.


And yet again.... you show your lack of knowledge on a subject. Yes, you can design a header to have a scavenging effect on exhaust flow from the engine... which NONE of our header designs do. But who said that is the only thing that constitutes "tuning"? Anything you do that can improve the power or driveability of the car can be considered tuning. Since cars are required to have an exhaust system to be technically street legal in all 50 states, and anything you can change on the exhaust that improve flows and lessen restriction will lower power losses and effectively increase the maximum HP at the wheels, that can be considered "tuning". Duh :rolleyes:. Oh yeah... PERIOD! lol

surfermatt95
05-31-2012, 10:13 PM
well, that was interesting to read lol , i may be moving to oregon here soon anyways so i will need a cat to pass emissions

locoman99
06-01-2012, 12:59 AM
bad advice again...

surfermatt95
06-01-2012, 05:13 AM
Only worry about it if they have a visual inspection or sniffers. Most places just have obd2 plugin testing. I know lots of cars that pass emissions here without cats. There puter only knows what yours tell it. It is not the end of the world to run catless, regardless of what a couple of self appointed know it alls might say.
i dont think ill be racing it since the previous owner didnt take too good of care . so ill just put one on to be safe

jd99gagt
06-01-2012, 08:01 AM
what about how how it runs,if i disable rear 02 codes than it won't run in open loop mode?I was gonna run no cat and stock muffler.

rocketfast123
06-01-2012, 08:45 AM
;1178860']

But my point remains, eliminating a cat on a street car is stupid and pointless.

You just mad because your state has inspections.


But if you have the right O2 sim, it will run fine. I don't have a cat or res on a 90 tech 4. It just has some mangaflow knock off muffle with a res tip. No ses,no hard cold starts, no bad smells, and sounds like a bad ass little diesel tractor. The tech 4 was not the best sounding engine. Can't say if power was lost since it only has like 92hp.

mfuller
06-01-2012, 09:56 AM
Whether your region does emissions testing or not, if your car came from the factory with a catalytic converter, it is illegal to remove it.

Catalytic Converter Laws
Rules for Replacing Converters
In 1986, the U.S. Environmental Protection Agency issued new guidelines for the construction, efficiency and installation of aftermarket catalytic converters. All CleanAir converters listed in this catalog have been designed, tested and manufactured to meet this policy.

In addition, CleanAir converter listed in this catalog is appropriate for use under the current requirements of the California Air Resources Board (C.A.R.B.).
E.P.A. guidelines state that replacement converters may be installed only in the following situations:

1. The vehicle is missing a converter
2. A state or local inspection program has determined that the existing converter needs replacement
3. Vehicles manufactured prior to 1996 must have more than 50,000 miles, and a legitimate need for replacement must be established and documented
4. In cases of OBD Il-equipped vehicles (1996 and later), the O.E. manufacturer's 8-year/80,000-mile warranty must have expired and a legitimate need for replacement must be established and documented.
Please note that Federal law prohibits removal or replacement of a properly functioning O.E. converter.

When replacement of the converter is appropriate (as outlined above), the E.P.A. further requires that:

1. It be installed in the same location as the original
2. It be the same type as the original (i.e., two-way, three-way, three-way plus air/three-way plus oxidation)
3. It be the proper model for the vehicle application as determined and specified by the manufacturer
4. It be properly connected to any existing air injection components on the vehicle
5. It be installed with any other required converter for a particular application
6. It be accompanied by a warranty information card to be completed by the installer.


Source: http://www.catalyticconverter.org/law/index.htm

locoman99
06-01-2012, 11:16 AM
not relevant to thread.

AaronGTR
06-01-2012, 05:54 PM
jeeeeez dude ...

Who said that comment was directed at you? I meant the epa types in the government that try and tell us what to do...

Its alwaaays about aaron...


Same thing. I think the EPA serves a useful function, and I also think running a daily driver without a catalytic convertor is irresponsible, regardless of whether there are any technical merits or not. If it's not a race car, there is no reason to run without one, except for being a stupid douchebag.

[ChaosweaveR]
06-01-2012, 06:00 PM
Same thing. I think the EPA serves a useful function, and I also think running a daily driver without a catalytic convertor is irresponsible, regardless of whether there are any technical merits or not. If it's not a race car, there is no reason to run without one, except for being a stupid douchebag.

:applause: Thank you.

locoman99
06-01-2012, 07:27 PM
The thread is related to cats...

mfuller
06-01-2012, 09:05 PM
Okay....that went downhill in a hurry.
Rule of thumb - if you wouldn't say it to your grandmother, don't say it here. This is still a public forum.

locoman99
06-01-2012, 09:14 PM
;1178992']You're my entertainment.

Post a picture of your car, you lying sack of dogsh!t.

Lol...u mad bro? I go take my break and ur still here havin a hissy fit. Ill make u a deal...u stay on subject for this thread(for your own good) and explain to me why an engine needs backpressure and I will post a bunch of pics of my car soon( i guess its a widespread problem with people falsly claiming to own grand am gts, because it is such an exclusive car...lol) if not i guess u will have to just look at the pic on my profile til i choose to make time and post some...of course, i will post in the correct area.
Now since we are in the tech section, lets get back on the subject of the thread... Now u where saying an internal combustion engine actually needs backpressure...please explain the dynamics and physics behind this principle you have discovered and stop this child like bickering.

AaronGTR
06-02-2012, 12:02 AM
Actually the hi flow cat u have on your car violates the epa law, so put your money where your mouth is and take off and while u are at it put your egr back to its stock configuration because that violated the law also...hypocrite




grrr. Reeeeaaaallly? Why do you have to be such an I D I O T ?



You should shut your mouth before you put your foot in it... again. Removing the EGR is not illegal. Removing the cat is... unless it fails.... stupid. Catalytic convertors have a limited lifespan. Same as the rest of the exhaust. The exhaust has a 6 year warranty from the manufacturer for integrity and function of the cat. If it fails before that, GM has to replace it... regardless of the 3 year general warranty on the rest of the car. Try reading your warranty sometime. You'd know that. If it fails after 6 years, you are responsible for replacing it. You can change it out for any type of cat you want... as long as there is a catalytic convertor on the exhaust it is legal. Try doing some research next time before you open your big mouth.

And at least I give enough of a **** about my fellow citizens to make at least that much effort not to pollute the environment that we all live in. That their children and some day my children and grandchildren will inherit. You sound like a typical conservative republican though... only care about yourself and only about right now. :rolleyes:


Who's the hypocrite?

GrandAmMe
06-02-2012, 12:19 AM
This is the most action i've seen on here in ages lol

[ChaosweaveR]
06-02-2012, 12:23 AM
*wall of whiny text*

>implying you own a grand am

locoman99
06-02-2012, 12:27 AM
grrr. Reeeeaaaallly? Why do you have to be such an I D I O T ?



You should shut your mouth before you put your foot in it... again. Removing the EGR is not illegal. Removing the cat is... unless it fails.... stupid. Catalytic convertors have a limited lifespan. Same as the rest of the exhaust. The exhaust has a 6 year warranty from the manufacturer for integrity and function of the cat. If it fails before that, GM has to replace it... regardless of the 3 year general warranty on the rest of the car. Try reading your warranty sometime. You'd know that. If it fails after 6 years, you are responsible for replacing it. You can change it out for any type of cat you want... as long as there is a catalytic convertor on the exhaust it is legal. Try doing some research next time before you open your big mouth.

And at least I give enough of a **** about my fellow citizens to make at least that much effort not to pollute the environment that we all live in. That their children and some day my children and grandchildren will inherit. You sound like a typical conservative republican though... only care about yourself and only about right now. :rolleyes:


Who's the hypocrite?

more stupid whiny text.

[ChaosweaveR]
06-02-2012, 12:36 AM
not relevant.

locoman99
06-02-2012, 12:44 AM
not relevant.

chris_gt_74
06-02-2012, 01:10 AM
I'm in Texas and removing the cat, egr or disabling it will fail inspection. But all we have in my area is visual inspection. There is no emission testing or odb2 testing near me.

locoman99
06-02-2012, 02:22 AM
But aaron loves the children and is a great democrat and american so when he hits the dyno again he will have a ceramic core cat and fully functional oem egr system.

But no prob...he gots all that knowledge you know...n he is just an all around good guy.

locoman99
06-02-2012, 02:33 AM
Good night and good luck

http://www.youtube.com/watch?v=zQHLthLLZXo&feature=youtube_gdata_player

[ChaosweaveR]
06-02-2012, 07:56 AM
not relevant.

AaronGTR
06-02-2012, 08:12 AM
But aaron loves the children and is a great democrat and american so when he hits the dyno again he will have a ceramic core cat and fully functional oem egr system.

But no prob...he gots all that knowledge you know...n he is just an all around good guy.

Whatever. I've never read anything anywhere saying removing the EGR is illegal. Removing it was necessary for my setup with the supercharger, as was modifying the PCV system. Also the thing about the cat and obd1 is recent. That was not the case when I bought it 4 years ago. At least I kept the PCV system in place, since it's good for the car and there's no need to eliminate it. That's better than most people on here who decide they want to eliminate the PCV and put a valve cover breather on. That's far worse than taking the EGR out, since it directly sends unburned fuel and combustion contaminants into the atmosphere. The impact from removing the EGR is minimal since I still have a cat and most of it is burned in there. So at least I TRY and make a positive choice.... unlike you, who don't care about anyone but yourself. I also ride my bike to work most of the time, so I'm not even driving my car that much, or using as much gasoline, and I obsessively recycle. What have YOU done to minimize your impact on the environment lately?

I would try shutting your mouth. That would greatly reduce the amount of air born pollutants being emitted. lol Want to keep this up? I can do this all day.

locoman99
06-02-2012, 08:39 AM
Here is your link to the law... Clean air act. Yep u gotta lose your blower because of the dems...irony huh? Egr cannot be tampered with or altered. You should do some research before you open your mouth. Read it and educate yourself. After you get off your soapbox about how legal and rightious you are you need to get to work figuring out how to make your car street legal again.

http://docs.google.com/viewer?a=v&q=cache:p3yGGJu6mWMJ:www.epa.gov/region4/air/sips/fl/Chapter-62-243.pdf+Clean+air+act+tampering+pollution+control&hl=en&gl=us&pid=bl&srcid=ADGEESg4-U6V9mzN3S3QgNc_m1CQug0HSYYStE-04cAXNxLEH3Y1qFRLoa8kUwPwbkxP13Su3VvHI5lSXiap7cxXH HaTONFE_9PxxXIlBWttBNYih4R8OJNwBHoekaGiY03aOAfLCju Y&sig=AHIEtbRtqmLinJr-GLE7BCJn0p6h4FKGDw

locoman99
06-02-2012, 09:54 AM
not relevant.

jd99gagt
06-02-2012, 10:45 AM
I was gonna have this custom exhaust shop mke it so you can adapt a staraight piep in place of the cat, so you can put it back on if you need. How do you get it to run normal w/o a cat?

[ChaosweaveR]
06-02-2012, 11:43 AM
I was gonna have this custom exhaust shop mke it so you can adapt a staraight piep in place of the cat, so you can put it back on if you need. How do you get it to run normal w/o a cat?

Did you even read the posts? lol

AaronGTR
06-02-2012, 01:52 PM
Yeah.... I like how just because I care about environmental issues, that automatically makes me a democrat too.... even though I've repeatedly said I'm not.


If anyone cares to have the information (accurate info that is), the important part of a catalytic convertor is the core with the matrix which has a special coating containing platinum. That is the "catalyst" that starts the chemical reaction to burn pollutants. It doesn't matter if I have a metal core or ceramic core. They both have the coating so they both work. The difference is, the smaller the core, and the larger the holes in the matrix, the less surface area the matrix has to work. Therefore it is less efficient and also takes longer to heat up so it takes longer for the cat to start working on a cold start.

THIS is the reason why the link I provided earlier in the thread had a cat with a 16" core instead of the smaller 12" core available. It would be less likely to set a check engine light because of the larger core. Anyway a factory cat is much more dense and contains much more platinum which is why they are worth more money at a recyclers compared to an aftermarket cat. But you can still do alright with an aftermarket cat if you get it properly sized and keep enough heat in the exhaust. That's another reason I recommend ceramic coating for people with headers, besides the performance and durability benefits.

As for me, I could certain switch to a more efficient cat if I wanted, and since I have an electric cutout I can use at the track, it wouldn't make much difference. Anyone else could do the same and get the best of both worlds. Since I already have a working cat though, and have spent a lot of money on my setup already, I'm not going to change my cat just to satisfy locodouche's vindictive nature. At least I have a cat, and I'm not going around telling people to take theirs off like an idiot.

Now that that's settled... I don't think this thread is going to accomplish anything more, so it's getting locked. Make sure to thank loco next time you talk to him. :rolleyes: