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Bernd
GenIII
 
4/01/2001
15:22:49
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 Subject: RE: Removing Cat on '01 4.7
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Another example:
MAP Signal: There are parameters in the PCM that look at the MAP reference voltage and compare it to a variable or static table. If you change out to a larger bore TB or an aftermarket cam (overlap comes into play on this), the pressure drop is quicker than with the stock throttle body. (Also what's considered a timing issue.)
As for building a 8-second 'Cuda...I've seen many capable of that (not just 'Cuda's...and not just Mopars). Nothing new to me. It's old technology with some electronics and a lot of parts matching. Try that in conjunction with using the modern MPI systems...it's not that easy. Custom PCM programs or custom PCM's are required (and Speed Density systems are more commonly used than Mass air for this). MAP, O2, and TPS are the main players in tuning this. Getting them to the right calibrations (timing again) is essential.
Bernd D. Ratsch
1997 Dodge Dakota SLT
Supercharged w/Nitrous
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matt
Mechanic
4/01/2001
18:41:24
| RE: Removing Cat on '01 4.7
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Ok all by that berd. the High perf. issue was with some one else not you. I have seen your truck and have read what yu have done to it, and I think it is very impressive.
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Bernd
GenIII
4/01/2001
20:43:13
| RE: Removing Cat on '01 4.7
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Oh...oops...hope I didn't offend ya on those comments.
Bernd D. Ratsch
1997 Dodge Dakota SLT
Supercharged w/Nitrous
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matt
Mechanic
4/02/2001
00:15:59
| RE: Removing Cat on '01 4.7
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Message:
naa, no offense taken
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CyberWolf
GenIII
4/02/2001
10:23:03
| RE: Removing Cat on '01 4.7
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Message:
I was the one that made the high performance mechanic comment. Sorry Matt, been there done that on the 8 second thing. And I did it in the quarter, not the eighth. Honestly though, I have only been able to run 9's with a couple of my engines. I'm a Chevy Mouse guy though. The 360 (yes I said 360) in my '85 Chevy pickup is the last engine I built (about 3 months ago) It pushes 430 hp (street legal) with 475 lb ft torque. All of this matters very little. I made that comment because it seems that when it comes to this performance stuff I haven't heard anything from you that really made since when I thought about it. I have always known that when the cat is removed it COULD give a false reading with the o2 sensors. That is why I asked the question. Let me guess, if you had a Mustang Fox body you would leave the stock h-pipe on because that is the way it was meant to be from the factory. You had NO good come back to what I said in my long post that questioned your mechanic ability. Shall I say it again?
"I know what kind of effects could happen by removing certain cats. I guess you think that people that run off-road H pipes on Mustangs are ruining their engines also. By the way, if you are a mechanic than you know that installing an off-road H pipe on a mustang removes 2 cats and 2 resonators. Damn if they don't gain 8-10 hp by doing that with no BAD effect on the engine. I have removed the cats from several vehicles besides Mustangs and got nothing but good results. Granted, a '98 Mustang GT that we just installed an H pipe on has the check engine light on now but they make a PCM that corrects that."
What do you have to say to all of this except "I built (or knew a guy that built) a Cuda that runs 8s."? Is that 1/4 or 1/8? If that is 1/8, keep working at it, you'll have a fast car someday. Also, if you think that the 3-way cat is anything near a highflow cat (like you said earlier), do some research.
To all of the tree huggers out there, hehehe. I'm only talking about removing one of three cats. Do you give mustang guys and rice burner guys the same lecture? For a performance forum, I have never seen so many people afraid of removing a cat.
I apoligize to everyone, except Matt, for having to read all of this petty arguing. I appreciate everyones posts. I joined this forum because I hate all of the petty arguing and this forum seemed to have almost none. Now here I am involved in the petty arguing and cut downs. For that I am sorry.
Back to the issue. Bernd, so after everything that has been said, what do you think? Will removing the 3 way cat and adding the Kat Box add noticable power? Is it doable? Remember, I would make it a bolt up deal with a couple sets of collectors so that I can reinstall it for the emissions check. Also remember tree huggers (hehehe), the emissions on this engine even with the cat removed will still be far better than probably 90% of the vehicles on the road.
'01 4.7 CC, 5 speed, Sport , 3.92 limited slip, Intense
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Bernd
GenIII
4/02/2001
10:32:29
| RE: Removing Cat on '01 4.7
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Message:
Since you're not removing ALL of the cats..hehehehe...i'll refrain from any "Tree Hugger" comments. ;)
If you have a O2 sensor(s) after the last cat, you may have a problem. In your specific case, I haven't heard of anyone doing this (yet) so your guess would be as good as mine. (Worth a try though.)
Bernd D. Ratsch
1997 Dodge Dakota SLT
Supercharged w/Nitrous
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matt
Mechanic
4/02/2001
12:24:39
| RE: Removing Cat on '01 4.7
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Message:
Your fox body car is completly diff. from what we are discusing here and now. the diff is the computer system on the autos. The old ford had the first gen computers that are not much more than if and that computers( if this sensor reads this this should be taht) in laymans terms so you understand what I'm saying. They also only had uno o2 sensors and they have nothing to compare the signal two other than the factory preset. The new system uses two sensors and compare the front to the rear or upstream to the downstream to see if the mix needs to adjusted, it also tells the computer if the cats are doing there job. If the computer does not see the right changes It will set off the check engine light and make the truck run real bad. There are many ways around this but I will not even go there it is not worth the proformance gains and I do not think it is worth making you truck illegal in all states for 5 hp when you can do other mods and gain more.
If you want to be a bonehead be my guest.
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CyberWolf
GenIII
4/02/2001
13:35:22
| RE: Removing Cat on '01 4.7
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Message:
Matt, I'm going to be the bigger man and step down. You made a good point about the o2 sensors. I think you are wrong because of the placement of the o2 sensors. But hey, thats what I posted this for, to get peoples thoughts. Your post rubbed me the wrong way due to the quotes "Go ahead and ruin your truck" and "In short leave the damn thing alone"
Bernd, I think the last o2 sensor is way ahead of the last cat. I'll have to look again and make sure though. Hell, I could always weld it back on. I only wish I knew what I might gain by doing this. I'm still only thinking about doing it. I posted this to get other peoples thoughts. Thanks for your thoughts on the subject.
signed,
CyberWolf (destroyer of the environment)
'01 4.7 CC, 5 speed, Sport , 3.92 limited slip, Intense
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matt
Mechanic
4/02/2001
14:38:13
| RE: Removing Cat on '01 4.7
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Message:
You ask for peoples opionions dont get mad when youget them. I'm not tring to argue. When some one asks a ? and I think I have the answer I give it. The second or downstream is about three inchs behind the last cat.
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matt
Mechanic
4/02/2001
14:40:28
| RE: Removing Cat on '01 4.7
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Oh forgot to say that I do not think cyberwolf is the destroyer of the enviroment.
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CyberWolf
GenIII
4/02/2001
15:03:39
| RE: Removing Cat on '01 4.7
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Message:
Matt, I don't mean to keep argueing but I just took a second look at my o2 sensors. Both o2 sensors screw into the front cat. One screws into the pipes just in front of the front cat and the other screws into the backside of the front cat. Then there is nothing but about 1 foot of pipe to the y pipe. Then there is about 2 1/2 feet of nothing but pipe to the 3 way cat. After that last cat there is still nothing but pipe to the muffler. This is the reason that I can't understand how removing that 3 way cat could hurt the reading on the o2 sensors. Both of the o2 sensors are about 10 inches away from each other. Also, the fact that they are both about 3 1/2 feet in front of the cat that I want to remove tells me that there is no way they can effect the o2 readings. As far as speeding up the air flow possibly causing inaccurate readings, that seems impossible also due to the fact that the last o2 sensor is actually in the cat as opposed to being in the pipe after the cat. Therefore it seems to me that the Kat Box shouldn't even be needed. I am almost 100% positive that this will work. The only thing keeping me from doing this is not knowing how much I will be gaining. As you said Matt, it may not be worth it to only gain 5 hp. 3 way cats are very restrictive though. I could possibly gain up to 15 hp. There is no way to know for me because I have no access to a dyno (without spending a shit load of cash). Also, even if it is only 5 hp, that could be enough to push me over the edge of spanking all the little RTs around here, hehehe. Bernd, does all of this sound right to you?
'01 4.7 CC, 5 speed, Sport , 3.92 limited slip, Intense
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matt
Mechanic
4/02/2001
15:14:30
| RE: Removing Cat on '01 4.7
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Message:
Okay I maybe able to help with this. On your exhaust the last cat should be near the transfercase right close to the transfercase should be an o2 sensor. If not the changed more than thought from 2000 to 2001. If there is no o2 sensor behind the last cat hollow the damn thing out and go on. Make sure that you are correct in that there is no o2 sensor behind the last cat. If there is and you hollow it out any way you will know shortly. Your gas mileage will go way down,( if you think it is bad now just wait) and performance will suffer instead of increasing.
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matt
Mechanic
4/02/2001
15:27:29
| RE: Removing Cat on '01 4.7
IP: Logged
Message:
Okay. I dont think my last replie went through I think I can help. If you look up next to the transfercase there should be an o2 sensor right behind the last cat. If not they changed more than I thought the had from 2000 to 2001. If it is true and you do not have an o2 sensor after the last cat you can hollow that last cat out without damaging anything other than mother nature. If you hollow out the last cat. make sure to install a pipe into the body of the last cat. Without the pipe the last cat could cause a venturie effect might be good might be bad( would not want to chance that) I would just put the pipe in after hollowing it out.
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CyberWolf
GenIII
4/02/2001
17:22:54
| RE: Removing Cat on '01 4.7
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Message:
Matt, We have both a 2000 4.7 and a 2001 4.7. The exhaust system is pretty different. There is no o2 sensor after the one that is in the front cat. I don't have a transfer case being 2wd but I know where you are talking about. So now that we have all of this pretty much figured out, I wonder what kind of gains I can expect? If this is a good power gain this could be a quick and free 5-15 hp. Of course, I only recommend this for off road use only, hehehehe.
'01 4.7 CC, 5 speed, Sport , 3.92 limited slip, Intense
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matt
Mechanic
4/03/2001
02:18:09
| RE: Removing Cat on '01 4.7
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Message:
You could expect 5 to 10 hp this way. But remember that you could have the reverse effect if you do not install a pipe straight through the cat. This is from the fact the convertor espands and contracts causing a venturie and will increase back psi.
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CyberWolf
GenIII
4/03/2001
09:18:13
| RE: Removing Cat on '01 4.7
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Message:
I'll probably weld up a straight pipe with a colector on each end so that I can bolt in the cat when I go to have it inspected or take it out when I go to the track. Also, that way I won't ruin my cat. That 3 way cat looks like it might be kinda expensive.
Thanks everyone for your help.
'01 4.7 CC, 5 speed, Sport , 3.92 limited slip, Intense
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teamfast
Dodge Dakota
JOIN HERE
2/17/2002
17:57:39
| RE: Removing Cat on '01 4.7
IP: Logged
Message:
So CW, now that you have done this, indulge
me as to how it performs. Is it louder?
My dilemma is a drop will reduce my
clearance for a dual exhaust set up so ive
decided to exit before the rear tyres on the
right. this however requires me to move the
muffler up 3 ft and so removing the third cat is
just a bonus.
I plan on 3" piping it from the headers to
muffler, up and over the frame rail and out
before rear tyres. I dont wanna chop up my
stock exhaust anymore than i have to (in case
i have to put it back on to sell) . Its stainless for
cryin out loud!
Thanks. Ryan
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CW
GenIII
2/18/2002
18:54:54
| RE: Removing Cat on '01 4.7
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Message:
I just cut it at the collector and got the guy to replace it all to the muffler. If it needs to go back in I will just get it welded. Performance wise I would say increased the revability by 500 rpm and gained HP all over the curve. I love that part.
2001 RC 4.7 5sp 9.25" 3.92 LSD
Ported 68mm throttle body, IAT adjuster, 3" flowmaster cat back, TPS @ .76V, 4" cold air, Roadmaster active suspention, Removed Third cat. Electric fan Convertion, Awaiting HO cams.
Working on adjustable fuel pressure with return.
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btt
Dodge Dakota
JOIN HERE
3/19/2002
21:17:20
| RE: Removing Cat on '01 4.7
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btt
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