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dweishaar
GenIII
 
9/10/2002
00:11:51
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 Subject: Cat removal
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a buddy of mine has a speed shop, and we're constructing a swap system for my truck. (i can remove my cat and swap it for a strait pipe, and vice versa for smog down the road, then un plug the cat and put the strait pipe back in after words with no welding, pretty sweet little set up) but any way, would this affect my O2 sensor? i was pretty sure that it was forward of the cat, but a frind of mine says its behind. i obviously don't want to hurt the truck for 3-4 hp and better sound. can anyone help?
One Eyed Fox
The Baja Dak
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CW
GenIII
9/10/2002
08:57:46
|  RE: Cat removal
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The 02 sencors are only behind the precats not the main cat.
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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polchartude
Dodge Dakota
JOIN HERE
9/10/2002
09:34:26
|  RE: Cat removal
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Removing the cat without altering the pcv system will have an affect on your fuel management system. ie.fuele pulse freq. will be wider to accomidate for the increased 02 reading.but there are 2 ways to fool the pcm. to achive a richer fuel to air ratio.
1.move the a.i.t. sensor to a cool locatin and plug the hole in the manifold w/ a 1/4" nps plug
this decrease in voltage will decieve the pcm into thinking the ambient air temp is colder than it really is, therfore increasing fuel mixture this will compensate for the low 02 reding.
2.remove the pcv vlve and hose from the vlv. cover and put an air breather on it. and cap off the vacume to the Tb from the vlv. cover this eliminates the low 02 readig from the sensor due to elimination of the need to burn the non combustable gasses from ur crankcase
I have done all of this(both mods)and have seen a dramatic increase in power and milage.
Ps. you won't get any mil lights or codes ar at least I didn't Hope I have helped..
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Ty
Dodge Dakota
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9/10/2002
10:04:28
| RE: Cat removal
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I removed my cat on a 98 r/t it was a pain in the ass with the o2 sensors u just have to plug them back in where you took them out make sure they won't fall out i havn't had a problem yet and its been 5 months
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CW
GenIII
9/10/2002
14:25:23
| RE: Cat removal
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polchartude: The cat has nothing to do with the PCV system. Don't bother giving adivce unless you know what you are talking about.
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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Duner
Dodge Dakota
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9/10/2002
14:32:16
| Hahahaha
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I'm gonna take my pcv valve out of my valve cover and see how fast I can go! ;>)
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polchartude
Dodge Dakota
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9/10/2002
14:54:14
| RE: Cat removal
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It's obviouse u are the one who should not be giving advice. Cause if u have ever anylized emisions before and after tossing the pcv system u would know that the only reason for the cat is to burn those gasses. and that's why this mod is proly not leagal in most emmission resrtictive states. because the blow-by gasses vent out of the crankcase breather and into the atmosphere rather than being sucked into the intake and burned in the CAT! most all <70's 300+ v8 didn't burn crankcase fumes and most modified 300+ v8 today toss that crap out too. Face-it it's just not efficient to burn hot gasses low in oxygen that arn't combustable when compressed . But u knew that anyways ur a tech right CW ? What's ur 1/4 times ?
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polchartude
Dodge Dakota
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9/10/2002
15:09:05
| RE: Cat removal
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If u don't like my responce or think I should keep my advice to myself perhaps u should contact sandman and ask him , maybe he's smarter than myself and has a faster truck than me. mabe u should be the forum advisor due to ur advanced capacity to comprehend and explain technical data to those who are the lesser.
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xplikt
GenIII
9/10/2002
15:13:38
| RE: Cat removal
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CW had to push the big red button.
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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Rob
GenIII
9/10/2002
15:43:39
| RE: Cat removal
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"u should be the forum advisor due to ur advanced capacity to comprehend and explain technical data to those who are the lesser."
He got one thing right!polchartdude-if you would research before you post you would realize he has a 2001 4.7 which has 3 cats.he is talking about removing the third cat which has no o2 sensor.I dont want to waste my time arguing with you and you shouldnt waste yours arguing with CW and Duner whom in my opinion are the only two guys on this board with the knowledge and the BALLS to try things on there own.
nuff said!
1NICEDAK
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Texas Todd
Dodge Dakota
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9/10/2002
15:54:09
| RE: Cat removal
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Message:
IMHO, all these posts have correct technical merits. Some of which are posting about something, not directly related to the original post.
Let's not get bent out of shape, and get the forum shut down again.
I'll be putting my HO cams in soon, CW, did you take off your fuel lines with the special tool, or just carefully move them?
Todd Bouton
01, QC, 4.7, 5spd, LSD(good stuff), P&P TB, homebrew air&K&N, no belt fan, 180t-stat,
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CW
GenIII
9/10/2002
19:26:40
| RE: Cat removal
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I have the special tool in my tool box at work, so I used it. You can just unbolt the injector rails and put them off to the side. Tie them up with wire or something.
The reason I called him out was I am sure it is the guy I delt with before and giving the same scewed advice. If not I apologize.
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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dweishaar
GenIII
9/10/2002
20:46:53
|  RE: Cat removal
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Message:
so,.......... basically there are only two o2 sensors behind each pre-cat, and i don't have to worry about anything electrical when we do the mod?
One Eyed Fox
The Baja Dak
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Texas Todd
Dodge Dakota
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9/10/2002
22:49:24
| RE: Cat removal
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Thanks CW for the answer to a question that was tangentially put into this thread.
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QUADMAN
GenIII
9/11/2002
00:37:35
| RE: Cat removal
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Ok, I'll put it into simple terms, our 2001 4.7's have 3 cats really, 2 pre-cats that are located near the manifold and the main large cat that is located under the truck cab. Only the two pre-cats have o2 sensors so you can remove the large main cat with no problems at all.
P.S. CW and Duner are by far two of the most educated tuners on here so make sure you really know your crap when you go to busting on their posts or you just might get your pcv fouled up!
OPINIONS ARE LIKE....WELL, YOU KNOW THE REST!!
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CW
GenIII
9/11/2002
09:25:03
| RE: Cat removal
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dweishaar: Yes no worries with the O2 sensors.
I have no problems with anyone coming on to any thread weather I have posted or not. Just don't give out misleading information thats all.
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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9/11/2002
20:37:11
| RE: Cat removal
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Since CW and DUNER are the only "forum certified technicians" to give advise in this forum(joke).I will ask them what do I need to do to put a pipe trhough the cat(straight pipe)if I have a 00 DQC with the 4.7L and only one cat w/O2 sensors on each side?. A far as I have read in this forum, I only have to worry about the one after the cat. That is if the info I read was accurate or it came from polchartude.(joke again). I will apreciate any technical info.
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Jacque
Dodge Dakota
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9/12/2002
12:33:15
| RE: Cat removal
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Gains of 5-10 horsepower are normal when installing a crankcase breather. I have personally seen 30 horsepower from a 429 Ford on a dyno that made 505. After installing 2 crankcase breathers it made 535. Just ask any professional engine builder that dynos their engines what gains they have seen. Polchartude is right this time it seems. The cat burns off any unburned gases in the exhaust and the pvc system recirculates blowby into the intake manifold to be used on the next intake charge. If the blowby is eliminated, that is that much less for the cat to burn off.
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polchartude
Dodge Dakota
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9/12/2002
12:41:02
| RE: Cat removal
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Thanx Jacque, Also one other thing to think about that also contributes to those gains is the decreased air intake temp. (crankcase fumes are very hot at high rpm.)
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Dakaty
GenIII
9/12/2002
20:03:10
| RE: Cat removal
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I think we should rely on Leslie to resolve this matter.
She installed a K&N valve cover breather(s) and would i) grace us with her opinion as the effect on performace/mileage and ii) let us know if it triggered any MIL lights.
Leslie, we're all counting on you.
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CW
GenIII
9/12/2002
20:44:07
| RE: Cat removal
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The ammount of air recircualted at WOT is nill because there is no vacuume to pull it in. That .00001% going into the intake doesn't equate to anything calcualatable. Blow by on any engine is so minimal that it doesn't effect the intake charge volume.
If you are talking about reducing windage by having a separate pump evacuate the crankcase I have seen gains yes. At 8000 rpm yes some gains. Some drag engines connect the PCV system straight to the exhaust and use the venturie effect to evacuate the crankcase but again a very radical and not street friendly system made for very high RPM applications.
Hey Duner pinch off your PCV line you will gain 50 hp since you have a turbo.
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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Duner
Dodge Dakota
JOIN HERE
9/12/2002
20:59:41
|  And that means ?????
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Polchartude and Jacque - OK, you're gonna have to explain this to me....
The tubing leading from my PCV valve is only 3/8" diameter. Exactly how much hot air/blowby do you think is going to go thru this dinky hose? How much blowby do you think these engines are generating? How much pressure do you think that air is under coming thru that little hose? Especially at only 4500-5500 rpms? It could possibly make some very small difference to the combustion process thru dilution of the intake charge, but the amount of unburned gases that come thru that little hose at 2psi will amount to about 1 cfm. Do you honestly believe that the amount of gases that come thru that small of a hose will make any difference to that catalytic convertor when you've already putting 650 cfm thru it? Do the Math!
I don't really care what anybody has seen on some high-tolerance, forged piston slapping 429 Ford race engine. If anybody believes they are gonna make 10-25hp by disconnecting the PCV valve on their modern engine I wanna sell them some beach front property here in Arizona. And you want us to believe that anybody was running a catalytic convertor behind a 535hp 429 Ford? And who the hell runs an engine on an engine dyno with a catalytic convertor on the system? Of course they saw an improvement by adding breathers.... who in the world would try building or running an engine without some sort of relief for the blowby? Especially a race engines that don't get to have all that break-in time for the rings to seal. They always have waaayyy more blowby than a street engine..... it goes with the territory.
Get the story straight!!! We ran NGK B8ES sparkplugs in the fuel altered and had to change them for every pass. WTF does that have to do with anything??? About the same thing as your story about some 429 Ford on some dyno! It makes a nice story - but you are pretty hard-pressed to apply any of the conditions or results to anything that we're driving.
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Duner
Dodge Dakota
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9/12/2002
21:19:07
| RE: Cat removal
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Doggone it CW!!!!!! You're giving away all my speed secrets!!!!
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polchartude
Dodge Dakota
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9/13/2002
06:28:44
| RE: Cat removal
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Sh!t dude already, don't know why u cling to ur pcv sys. but sh!t keep it on, and don't mess w/it. I forgot u know everythin, what do u pull, 13"s in the 1/4, trust me niether u or ur truck impresses me. Just 11.03 out of a 318 talkin here,but I'm not a "tech" I build engines and race cars in miss. but if ur so much smarter than me ad I shouldn't post cause I don't know what I'm talkin bout, how come my 98 Dak is presumably-not proven faster than yurs. before u even ask I don't have a scanner.
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Texas Todd
Dodge Dakota
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9/13/2002
08:43:13
| RE: Cat removal
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This thread is getting good..............
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CW
GenIII
9/13/2002
09:09:58
| RE: Cat removal
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Actualy Duner pulles 12.55s with a slipping clutch. Hehe.
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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DD
Dodge Dakota
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9/13/2002
10:18:50
| RE: Cat removal
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I think CW and dunner are married.
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DD
Dodge Dakota
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9/13/2002
10:19:00
| RE: Cat removal
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I think CW and dunner are married.
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Duner
Dodge Dakota
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9/13/2002
11:07:57
| Hahahaha - Typical Response!
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".....before u even ask I don't have a scanner"
That sounds about right.... in other words - "don't ask me to back up any of my claims".
Well I know I'm married.... but not to CW if that's what you mean. LOL
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Duner
Dodge Dakota
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9/13/2002
11:33:47
| Just being ornery I guess!
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Polchartude - I wanna apologize for jumping in your stuff and blowing your theory out of the water. I got carried away because instead of calling it an idea or a theory, you posted it like it was gospel. It's good to have everyone post their theories and ideas online so we can hash them out. The more we talk about this stuff - the more everybody learns about it.
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Demon Dakota
DakotaEnthusiast
9/13/2002
12:57:18
| RE: Cat removal
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Or you could just eliminate your cat. That would cause your cat to burn less as well.
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