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ErnieQuad03
Dodge Dakota
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9/30/2003
09:57:07
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 Subject: Quick Cat-Converter Question
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Message:
I have searched over the boards here and haven't decided upon the removal or replacement of my 3rd Cat on a 2003 4.7 V8 Quad Cab.
For those who have done it, or have experience with it, is it better to just remove the 3rd cat and put in a straight pipe or buy a Carsound High Flow cat. I live where emissions are not an issue.
I would prefer to straight-pipe it since it is the least costly, but don't want to hurt performance.
Reason I am asking is I think a lot of cars/trucks perform differently in this situation. I had an '89 Formula 350 Firebird, removed the cats and saw rough idle and bad performance, once I installed high-flow cats everything was great. Had an '85 Ramcharger with a 360 and it was fine by just removing the cat.
Since there is no 02 sensors associated with the 3rd on in the Dakotas, I'm guessing a straight-pipe will do.
What are your takes on it?
Thanks in advance!
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midnightdak
Dodge Dakota
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9/30/2003
11:23:58
| RE: Quick Cat-Converter Question
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You can just take it off and put a straight pipe on but it will cause your motor to run alittle rich and this will cause the plugs to foul after a while,believe mine have once already,i'm putting a cat back on sooner or later on my dakota.Performance wise its better to remove it,it did on my 2001 4.7 but i guess a highflow cat it would do just the same or better performance wise,and it would foul out the plugs,but if you want louder or something it didnt help my buddie has the same pipe and muffler minus i have no cat and mine is no louder than his is.Hope this helps.
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gps_jetskier
Dodge Dakota
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9/30/2003
12:47:14
| RE: Quick Cat-Converter Question
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Haven't noticed the cat causing the plugs to foul. Took it off and had a straight pipe put in. Nice sound now. Just right for me.
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Demon Dakota
DakotaEnthusiast
9/30/2003
13:44:57
| RE: Quick Cat-Converter Question
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Message:
How could removing the third cat, which is not directly involved with fuel delivery, cause your engine to run rich? It can't. As a matter of fact, it will run lean(er) if anything due to increased airflow (and ECM correction). If your plugs are fouling, then it's because of an entirely different reason.
K&N Drop in AF (CAI during summer months)
True Dual exhaust and removed third cat
HO Cams & HO Intake
FASTMAN 70mm TB
Autolite 3923 Plugs
TPS @ .76 VDC
IAT Adjuster Mod
14.52@94.2 MPH at Silver Dollar Raceway
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midnightdak
Dodge Dakota
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9/30/2003
15:17:16
| RE: Quick Cat-Converter Question
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my bad guys,didnt mean that its going to happen to everyone that takes off there cats,just saying what it did to mine,cut off my cat and my buddie did a check and to my surprise it runs rich now.The reason for it to do it to mine is because when i took of something that is supose to stay on the truck,thats why they put it there when it was made.This is not part of the feul delivery but it is part of the feul system though and taking it of could mess that up,thats why i said that,sorry you guys are prolly right,these new cars and there computer...lol...i did feel more power from taking it off so thats why i was telling him to cut it,just dont cut the cat into like the guy did that cut off mine,that way if you dont like it it can be put back on the truck.
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Demon Dakota
DakotaEnthusiast
9/30/2003
16:18:21
| RE: Quick Cat-Converter Question
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Message:
Actually, it's not part of the fuel system. It's emmisions system related. It's two purposes in life are to help burn excess fuel leftover from the combustion process and create a slight bottleneck in the exhaust (producing some backpressure and loss of efficiency)...
K&N Drop in AF (CAI during summer months)
True Dual exhaust and removed third cat
HO Cams & HO Intake
FASTMAN 70mm TB
Autolite 3923 Plugs
TPS @ .76 VDC
IAT Adjuster Mod
14.52@94.2 MPH at Silver Dollar Raceway
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Kowalski
Dodge Dakota
JOIN HERE
9/30/2003
16:32:41
| RE: Quick Cat-Converter Question
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Message:
Midnightdak, you seem a little confused. Lessening restriction in an exhaust system will cause an engine to run leaner, not richer.
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midnightdak
Dodge Dakota
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9/30/2003
19:18:29
| RE: Quick Cat-Converter Question
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Message:
Whatever guys...but remember this forum is not about me,but you lose back pressure by taking the cat off...why would you want to do that?Another reason the r/t's beat us by more.when it comes to computer sh!t i'll leave it for someone who knows that sh!t,i'm more on carburated 500+hp SBC and BBC motors.Computer stuff and cat converters do confuse the crap out of me...rich?...lean? what the fuk ever its loss of back pressure which in my opinion i wouldn't want to lose any of that on my 4.7.
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gps_jetskier
Dodge Dakota
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10/01/2003
07:48:36
|  RE: Quick Cat-Converter Question
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Message:
No...no....would want a nice free flowing exhaust....yer right.....
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ErnieQuad03
Dodge Dakota
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10/01/2003
09:41:41
| RE: Quick Cat-Converter Question
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Guess I'll stick with throwing in a high-flow cat if I decide to do something about the 3rd cat. For now, I think I'll just put the exhaust on. Still debating on the single or split dual type configuration.
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Kowalski
Dodge Dakota
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10/01/2003
17:00:40
| RE: Quick Cat-Converter Question
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Message:
Would you run a 500 hp SBC or BBC with a restrictive exhaust ? When you make claims that defy the laws of physics, it becomes about you, midnightdak ! Sure, you want some backpressure, but not too much.
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midnightdak
Dodge Dakota
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10/02/2003
00:33:58
| RE: Quick Cat-Converter Question
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Message:
no i wouldnt want a 500 hp motor thats restrictive in any way,but my dakota has a whopping 230 hp so i want some back pressure,thank you,thats why...back to the subject guys,this forums not about me and thats why i was replying to the question saying that i would NOT cut of the cat,because i(myself) lost some hp by cuting mine and thats why its back under there.
SUBJECT CHANGE!!! back to the point of this forum guys,this guy might still need help...and guess what?...some of you guys aren't helping.
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gps_jetskier
Dodge Dakota
JOIN HERE
10/02/2003
13:22:45
| RE: Quick Cat-Converter Question
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Message:
True. I'm sorry.
My vote is for the straight-pipe. Worked like a charm for me.
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Demon Dakota
DakotaEnthusiast
10/02/2003
14:12:25
| RE: Quick Cat-Converter Question
IP: Logged
Message:
midnightdak,
The loss of backpressure is totally insignificant if you just remove the third cat. It only has an effect on the idle backpressure. As a matter of fact, you'll get more backpressure with the third cat removed once the airflow has increased enough (like when you depress the gas pedal). The increase in airflow throughout the entire system, while still maintaining the stock exhaust inside diameter, causes an increase in running backpressure, thereby increasing torque. You get slightly more HP due to higher volume of air moving through the exhaust as well (which is why we run slightly more lean when removing the third cat). The stupid ECU doesn't compensate well enough to richen up the mixture (it's a utility truck ECU program, not a performance ECU...so I guess I'll forgive it). That's why when you remove the third cat and/or go to a true dual exhaust, you need to either relocate the IAT to a direct airflow part of the vehicle, or make the IAT adjuster (which according to my fuel/air meter, gives you a +2 to -3 incremental change in your overall fuel/air ratio). The stock F/A ratio from Dodge is 13.5-14.0:1. When I went to true duals and removed the third cat, I went to 15-15.5:1, and now have it adjusted to 14:1 again.
K&N Drop in AF (CAI during summer months)
True Dual exhaust and removed third cat
HO Cams & HO Intake
FASTMAN 70mm TB
Autolite 3923 Plugs
TPS @ .76 VDC
IAT Adjuster Mod
14.52@94.2 MPH at Silver Dollar Raceway
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