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FredDQC
Dodge Dakota
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10/02/2002
19:00:02
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 Subject: CAT CLEANING
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I read in this forum that to make the elimination of the cat converter worth, you have to brake the stone inside and put a pipe through the cat. Today I went to the muffler shop, and the guy told me that it was not necessary to put a pipe through because the input/output was in-line and not off-set. So he said that you just have to de-gut the cat and it should work as if it had straight pipe. Is this true? By the way my truck is a QC 4.7L 2000 with only one catalytic converter and two O2 sensors; one before and one after the cat.
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CW
GenIII
10/02/2002
19:35:55
|  RE: CAT CLEANING
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It will work but then, if you have to, you can't put it back on. Sometimes the hollow chamber makes for a weird exhaust note.
4.7 HO, CW style
2001 4.7 5sp 3.92 LSD
Ported 68mm TB, IAT adjuster, 3" flowmaster cat back, TPS @ .76V, 4" Z-tube, Roadmaster active suspention, Removed Third cat, Electric fan Convertion, HO cams, Robert shaw 180 therm, HO intake manifold.
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FredDQC
Dodge Dakota
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10/02/2002
20:48:36
|  RE: CAT CLEANING
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Well I was thinking on leaving the cat on it just wouldn't have anything in it.I really don't see any other disadvantage, exept for the one you mentioned about the specific noise. I wonder if there is anyone out there with that setup that could tell me how did affected the noise and performance. Thank you for the info CW.
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Jon
Dodge Dakota
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10/02/2002
20:58:05
|  RE: CAT CLEANING
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Gutting the cat or removing it won't give you any more power. The original cats were very restrictive, however since the mid 1980's vehicles have been using monolithic cats that are capable of flowing more exhaust then you would ever need unless you have headers AND head work AND forced induction. If the cat gets plugged due to a misfire condition, or the engine running extremely rich then it will decrease power, otherwise you are wasting time and money messing with it.
-Jon
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CW
GenIII
10/02/2002
22:17:36
| RE: CAT CLEANING
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Jon you need to stay a little more up to date as the cats on the 4.7 become very restrictive after 5000 RPM. It was Duner who pointed this out with dyno results of 9hp at peak and about 30 at 6000 I have to find the sheet. All you have to do is drive one without the third cat and you will be amazed at what it will rev to after that.
4.7 HO, CW style
2001 4.7 5sp 3.92 LSD
Ported 68mm TB, IAT adjuster, 3" flowmaster cat back, TPS @ .76V, 4" Z-tube, Roadmaster active suspention, Removed Third cat, Electric fan Convertion, HO cams, Robert shaw 180 therm, HO intake manifold.
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xplikt
GenIII
10/02/2002
22:26:11
| RE: CAT CLEANING
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Jon, thank you for that opinion, because that is all it is. You obviously have not done this on your Dakota, or you would be stating factual information.
However, CW and I both have removed our third cats and can give you straight facts.
I have heard gutted cats on Mustangs and Hondas and it does have an odd echo-like sound to it. I have never done this to a Dakota, so I am not exactly sure if it'll do the same. The cost is minimal and your cost in time to do this is maybe a Saturday morning one weekend. You could try gutting it first, then if you find the sound to be a bit odd, stick a straight pipe in there. Simple as that.
It's a super easy process and if you run into any problems you can always feel free to come here and ask!
What does it do? You have power and a mean sound beyond 5200. Your low end loss is not felt on the Butt Dyno.
<-- gives the thumbs up on guttin' that tin can.
2002 2WD RC SLT 4.7L 5spd 3.92 LSD
MBRP Single in/out, straight piped 3rd cat, turndown tip
Hotchkis swaybars and springs
Bilstein custom tuned shocks
Roadmaster Active Suspension
Shaved emblems and antennae
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Clevite 77
GenIII
10/03/2002
08:48:57
| RE: CAT CLEANING
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I have... first I removed my third cat, then a couple months later, I gutted it all out, and it's nothing like a straight pipe. As the exhaust enters the cat, it goes from a 3" pipe to a 4" (or so) pipe, then bottle necks down to a 3" pipe. Once I gutted it, I had it put back on, because I didn't want the dealer to say anything.
CW, it didn't really change the tone too much, it did quiet it a bit, and I did loose a lot of power in the higher R's (it made more power with it removed, then with it gutted and re-installed)
CW, will I have any problem with warranty work, if I was to remove it again?
"If my calculations are correct, when this baby hits 88 miles per hour, you're gonna see some serious shit."
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CW
GenIII
10/03/2002
09:13:05
| RE: CAT CLEANING
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Message:
That would be up to your local dealer. I doubt they would notice, unless they are looking for a reason to nail you.
4.7 HO, CW style
2001 4.7 5sp 3.92 LSD
Ported 68mm TB, IAT adjuster, 3" flowmaster cat back, TPS @ .76V, 4" Z-tube, Roadmaster active suspention, Removed Third cat, Electric fan Convertion, HO cams, Robert shaw 180 therm, HO intake manifold.
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Selcher
Dodge Dakota
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10/03/2002
09:19:22
| RE: CAT CLEANING
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So what you're saying is that on an '02 4.7L you can just simply cut off the third cat? Shazzam? Done deal? No codes thrown, nadda? I may cut that basturd off...
Regards,
Aaron
'02 CC 4.7L 4x4
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Clevite 77
GenIII
10/03/2002
09:39:18
| RE: CAT CLEANING
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Go for it Selcher, there's no o2 sensor after it, no codes for me.
CW, if they wanted to get me for something, can they? Like the old saying goes they have to prove that it caused the problem right? well removing the cat can't have any effects on anything can it?
Thanks CW, I appreciate your help
"If my calculations are correct, when this baby hits 88 miles per hour, you're gonna see some serious shit."
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Pistolero
Dodge Dakota
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10/03/2002
10:47:07
| RE: CAT CLEANING
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Message:
I'm not trying to influence or make a judgment on anybody's actions, just offering some info here, but I would just mention that it is a federal offense to modify or remove the catalytic converter on any legally registered vehicle in the U.S. I read that just the other day...
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Selcher
Dodge Dakota
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10/03/2002
11:20:41
| RE: CAT CLEANING
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Pistolero,
I live in Canada and the smog police aren't Nazi's so no worries there...
Regards,
Aaron
'02 CC 4.7L 4x4
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88dak
Dodge Dakota
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10/03/2002
11:27:58
| 88dak exhaust
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I have a 88 3.9L dakota 4x4 std. I was wondering what I could do with my exhaust to make it shound good I have eldebrock headers and the rest of the exhaust is stock, if I remove the cat would it give me more power? or will I loose power?and should I put duals after the muffler? should I get a different a muffler like a 40 series flowmaster. I just want to know what will make it sound good if you have any ideas let me know thanx
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dweishaar
GenIII
10/03/2002
14:44:18
|  RE: CAT CLEANING
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some one said earlier that their truck got quieter after they remioved their cat.......get behind it. f'ing LOUD. at idle, i can hear my truck from about 200 yards into my apartment complex. at 5000 rpm, the sound is ungodly. have someone drive your dak and get behind them when they punch it. you won't be dissappointed. after i removed my cat, it was windows down everywhere i went, regardless of temp. Pull the cat. if you live in cali, or are worried about dealers, e-mail me..i'll send you pics on what to do.
One Eyed Fox
The Baja Dak
Have you jumped a dak..........lately?
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FredDQC
Dodge Dakota
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10/03/2002
16:15:34
| RE: CAT CLEANING
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Message:
Ok! so far everyone here have talked about removing the third cat. Mine only have one cat with an O2 sensor in each side.I there anybody out there that have de-gut the single cat and notice any difference? as far as with the pipe and without the pipe?
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foleyr
GenIII
10/03/2002
16:39:46
| RE: CAT CLEANING
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Message:
Selcher
where are you in canada .. I am Ontario ..
Ryan
foleyr .. ..........
“Wise men talk because they have something to say, Fools talk because they have to say something”
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Clevite 77
GenIII
10/03/2002
16:47:22
| RE: CAT CLEANING
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FredDQC
in your case go to
www.speedtweaks.net
and they have an "o2 sim"
this plugs into the wire that plugs into your o2, Then you just remove the o2 sensor and cat. This tricks your computer into thinking the second o2 sensor is giving it a good signal. You'll only need one.
"If my calculations are correct, when this baby hits 88 miles per hour, you're gonna see some serious shit."
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Jon
Dodge Dakota
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10/03/2002
19:57:18
| RE: CAT CLEANING
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Message:
I'm not concerned about dyno results because they can vary by 15 HP or so depending on a hundred different variables, i would like to see flow bench testing of a catalytic convertor. Back pressure measurements befor and after removing that 3rd cat would be good too. The cat contributes very little to exhaust back pressure, and if it did contribute to backpressure removing it would cause you to loose as much low end power as you gained on the high end. Most racers remove the cats because they are running a 12:1 a/f ratio which would plug the cat. BTW what i am stating here is not only my opinion, but the opinion of master techs i have talked to at performance shops. Here is also some info i found on the internet.
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High-flow catalytic convertors ('cats') are also available, it is also possible to 'gut' the OEM unit. Typically this does not offer performance gains for street use and are effective only in the later stages of a build-up program when other more significant bottlenecks have been removed.
----
Anyone contemplating CAT removal should understand that not only is it illegal, but the performance of your car will NOT improve significantly. The noise it produces will "improve" - you are modifying a sports car and bringing it's performance in line with a 20 year old pickup truck. I make no apology for this statement. Let's be realistic. If you are an immature kid looking to get noticed, then this is the way to do it
--------
-Jon
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xplikt
GenIII
10/03/2002
20:46:50
| RE: CAT CLEANING
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Message:
Again, Jon speaks from generalizations only, not specifics.
When it comes to cars, everybody has their idea of what's best.
No apology is needed, you are free to speak your mind! However, talk is cheap and so is the internet. You are only repeating what you have heard, nothing from experience.
Although, I did forget to point out that it is illegal and becareful where you do it.
2002 2WD RC SLT 4.7L 5spd 3.92 LSD
MBRP Single in/out, straight piped 3rd cat, turndown tip
Hotchkis swaybars and springs
Bilstein custom tuned shocks
Roadmaster Active Suspension
Shaved emblems and antennae
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CW
GenIII
10/03/2002
20:56:36
| RE: CAT CLEANING
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Message:
Jon on the 4.7 it makes a decent difference. The 4.7 breaks alot of rules. It will breath all the way to 7000+ RPM on a 218° cam. Pushrod motors like the magnum will not. It likes alot of air as well where other motors do not. If dyno and track times are not accurate I have not idea what is. To your last statment there is no need to dip to that level. You will notice I also have a small cat in each side of the motor. I think everyone is smart enouph to know that removing the cat is at their own risk.
Clevite: Like I say it is up to your dealer from what I have seen. Why not ask and see what the reaction is.
4.7 HO, CW style
2001 4.7 5sp 3.92 LSD
Ported 68mm TB, IAT adjuster, 3" flowmaster cat back, TPS @ .76V, 4" Z-tube, Roadmaster active suspention, Removed Third cat, Electric fan Convertion, HO cams, Robert shaw 180 therm, HO intake manifold.
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Jon
Dodge Dakota
JOIN HERE
10/04/2002
07:25:51
| RE: CAT CLEANING
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Message:
The last part of my previous statement was not mine it was from a website about cats, although i don't agree with you guys i wouldn't resort to name calling. I can't say from experiance what will happen with them on a 4.7 but i have another truck in my driveway with straight pipe exhaust, i didn't gain anything by removing the cats.
BTW here's a good website: http://www.randomtechnology.com/technical.html
They dyno tested an lt1 motor w/ and w/o cats, they gained 3 hp when they installed factory cats.
-Jon
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FredDQC
Dodge Dakota
JOIN HERE
10/04/2002
17:49:16
|  RE: CAT CLEANING
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Message:
Thank you! Clevite77 for the info. Let it be clear that I want to remove the cat not because I'm an inmature kid like jon says but because I'm not used to them. The mayority of my life I have been driving mexican cars. Mexican cars don't have cats. so I guess everyone there is inmature. I do know for a fact that improves responseness in some engines. I had a Grand Marquis(american)with a 302 engine. I removed the cat and ran a straight pipe and I could feel the difference in performance and gas mileage. I do not know if it will do the same to the 4.7L but like I said I'm not doing it to get notice by having a louder truck. I just don't like cats and needed some info from experts here to bypass the post O2 sensor. I wasn't looking for advise on wether or not remove the cat. No ofense to those who provided info or advise. I'm pretty sure it was with the best intentions and I appreciate it.
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Jon
Dodge Dakota
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10/04/2002
18:26:07
| RE: CAT CLEANING
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Message:
Like i said, i didn't call anyone immature that part was from a website about cats, calling kids that remove them immature.
You can't drive a car with a cat because your not used to it???
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xplikt
GenIII
10/04/2002
19:01:36
| RE: CAT CLEANING
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With my MBRP muffler on there it isn't even that loud unless I take it to 5000. Do I get noticed? Hardly. The people who do notice me are other general truck fanatics and mechanics -- and they love it and ask what I did.
2002 2WD RC SLT 4.7L 5spd 3.92 LSD
MBRP Single in/out, straight piped 3rd cat, turndown tip
Hotchkis swaybars and springs
Bilstein custom tuned shocks
Roadmaster Active Suspension
Shaved emblems and antennae
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Cotharyus
GenIII
10/04/2002
19:48:56
| RE: CAT CLEANING
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Message:
xplikt - I know I've talked to you before, but tell me - how loud is the MBRP compared to stock exhaust? If anyone else wants to take a shot at this they can too. I'd like to hear (esp. from xplikt) a sound bite of the MBRP on the 4.7. When I had my cat work done (today), I didn't notice it got any louder, just a little deeper.
2001 QC 4x4, 4.7,5 spd, LSD, K&N Gen II Intake, Robert Shaw 180 Stat, Hanson Industries custom front bumper, Highflow cat
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CW
GenIII
10/04/2002
19:56:28
| RE: CAT CLEANING
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Mine had a 3" flowmaster on it with the three cats it was pretty quiet removed the third cat and it got alot louder. A little to loud for my tastes. I would like a more quiet muffler with out the HP going down.
4.7 HO, CW style
2001 4.7 5sp 3.92 LSD
Ported 68mm TB, IAT adjuster, 3" flowmaster cat back, TPS @ .76V, 4" Z-tube, Roadmaster active suspention, Removed Third cat, Electric fan Convertion, HO cams, Robert shaw 180 therm, HO intake manifold.
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xplikt
GenIII
10/05/2002
02:04:45
| RE: CAT CLEANING
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The MBRP is not super loud, but it's not quiet either. I'd have to say it's down around the middle.
If it's any help, my dad told me it's the sound he and his friends were trying to get three decades ago. Nice and mellow, solid sound.
My dream would be to have true dual 2 1/4 or 2 1/2 inch, x pipe, mandrel bent, MBRPs, with turn down tips a foot after the cab. Man I bet that would sound incredible!
A sound clip would be kinda cool. Maybe I should find a time a friend of mine can use his nice Canon DV cam to get something from it. Wont be anytime in the near future though.
2002 2WD RC SLT 4.7L 5spd 3.92 LSD
MBRP Single in/out, straight piped 3rd cat, turndown tip
Hotchkis swaybars and springs
Bilstein custom tuned shocks
Roadmaster Active Suspension
Shaved emblems and antennae
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FredDQC
Dodge Dakota
JOIN HERE
10/07/2002
16:29:53
|  RE: CAT CLEANING
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Sorry I refrase that; is not really me that is not used to but the car I'm driving. Often I find myself having to put mexican fuel and to tell you the truth mexican fuel and cats don't mix. That's why I always take out the cat on all the vehicles I have had in the U.S.
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DJDanRT
Dodge Dakota
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10/07/2002
22:26:55
|  RE: CAT CLEANING
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Jon
Of course the companys selling cats are going to say not to remove them and how they make less power, I mean after all they are in the cat selling business!! Are you one of the ones that has bought a TB spacer like the tornado or helix?(haha).
Bottom line is the cat is a restriction in the exhaust for emissions purpose only. Removing it makes less restriction(obviously). This isnt rocket science.
,Dan
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Dr Vinculum
Dodge Dakota
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2/02/2003
03:48:30
| RE: CAT CLEANING
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Message:
You guys that are cleaning out your cats, how exactly are you removing and reattaching the cat? I could cut the pipe with a cutoff wheel, but then how are you getting it back on? I could weld it together if i removed the entire exhaust and cleaned the rust coated pipes, but thats alot of work and who knows if it will weld ok. I was considering just replacing it with a pipe as well, i guess clamps would work in this situation, but it seems as if the pipe isnt perfectly round on my '99 dak. I want this to be as simple as possible. Mine has an internal rattle thats driving me nuts, and since i dont need it for inspections, off it comes! Just need a little insight on the best way to seal the exhaust back up!
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ShortSport
GenIII
2/02/2003
12:30:32
| RE: CAT CLEANING
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Message:
xplikt......man your suspenion mods sound really good. my quess is it handles much better than stock... if i could can i ask how much it all cost and how long it would take a average machanical guy with good tools to install all that....thanks in advance
2002 Reg cab 4x2 4.7 5-spd 3.55.1 LSD
fiberglass tonneau cover; stainless steel cat-back dual exhaust; magnaflow muffler
Go hard or go home!!
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