Cat removal??? so what...
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Senior User
Joined: Feb 2004
Posts: 438
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From: Ormond Beach
Cat removal??? so what...
the real deal? I have been told that if you remove the Cat only you will get better milage but that the vehicle's PCM needs to be re-programmed to accomadate the change.
What if you arlready have a tuner?
What if you arlready have a tuner?
Cargo Master
Joined: Oct 2004
Posts: 2,148
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From: Seneca, SC
cutting the cat will make for more exhaust flow, which could increase mileage. The problem is this, if you have two exhaust emissions sensors (not sure what you'd have on a diesel) one before the cat and one after, then you can get in a bad way easy. The second sensor will pretty much always signal rich, and I don't know of any way to trick the computer into thinking otherwise. Maybe somebody else knows different, but I'd go with a high flow cat if somebody makes one.
Senior User
Joined: Jul 2004
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From: W. Philly Burbs
from my simple opinion from what ive read on FTE the cat doesnt mean much or anythhing to thr 6. unless ur doing some seripus power work....and any basic tuner wont come into this "threshold".......therefore are the most gut it to keep ur dealer happy/////otherwise upgrade the exhuast and have fun.
BTW, 04 engine build on an 04 truck//////////////my downpipe is as clean and straight as can be (its fully rounded through the turns.....no kinks or cuts) ......no kinks...................it must only deal with some models/dates?
BTW, 04 engine build on an 04 truck//////////////my downpipe is as clean and straight as can be (its fully rounded through the turns.....no kinks or cuts) ......no kinks...................it must only deal with some models/dates?
Elder User
Joined: May 2005
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From: Tennesee
DougD,
Just so you know it's illegal. Now that that is out of the way the diesels have no O2 sensors or anything that will sense and kick a CEL, the factory computer will adjust for less back pressure by itself and the EGT's will drop because of less back pressure. removal of a cat on stcok exhaust is a minimal gain at best, to make it really work you need a larger mandrel bent system. Call us if you want we have all the MBRP system that aloow you to keep the cat totally stock or take it out for off road and racing use etc. Do NOT gut the cat, if you need to ever buy one you'll kill yourself when you find out how much they cost!
Mark @ DPPI
Just so you know it's illegal. Now that that is out of the way the diesels have no O2 sensors or anything that will sense and kick a CEL, the factory computer will adjust for less back pressure by itself and the EGT's will drop because of less back pressure. removal of a cat on stcok exhaust is a minimal gain at best, to make it really work you need a larger mandrel bent system. Call us if you want we have all the MBRP system that aloow you to keep the cat totally stock or take it out for off road and racing use etc. Do NOT gut the cat, if you need to ever buy one you'll kill yourself when you find out how much they cost!
Mark @ DPPI
Senior User
Joined: Jul 2004
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From: W. Philly Burbs
actuallly ive read in in places where the cat was removed n some 6.0s and the emission machine didnt bitch......................
Look at it this way, if a lot of people say the cat has almost no restrictive poilicy on the exhaust of the 6.0.........(AKA exhaust gasses) how can it "trap" many pollutants?
Look at it this way, if a lot of people say the cat has almost no restrictive poilicy on the exhaust of the 6.0.........(AKA exhaust gasses) how can it "trap" many pollutants?
Senior User
Joined: Jan 2004
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Originally Posted by Btravelen
I doubt that it makes much difference in performance at all compared to the damage it does to air quality by removing it, the good reason these things were put on in the first place. 
Last edited by BigF350; Feb 12, 2006 at 04:53 PM.
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Posting Guru
Joined: Mar 2004
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From: MI
Originally Posted by DougD
the real deal? I have been told that if you remove the Cat only you will get better milage but that the vehicle's PCM needs to be re-programmed to accomadate the change.
https://www.ford-trucks.com/forums/s...&highlight=vgt
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Senior User
Joined: May 2005
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From: Atlanta GA
Just modify the factory exhaust as a "sound test", this can be done for under $125. Less if you can weld. And if you just have to have a 4" and just have to have the brand name exhaust then you know what to order, cat delete or not. Like I have said before, I get guys asking on a daily basis what size, type, and who makes my exhaust questions. And they are very happy to hear that it is factory and cost me $120. I guess it just depends on your wallet and how deep it runs. Oh yeah, and just to avoid the "I told you so's" I still have my OE cat (in storage that is). Just in case I get the "no-no" finger from the EPA guys.
Posting Guru
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From: Tennessee
Originally Posted by drtry10
Boy, have I been waiting for some idiot to say this! First off a Cat on a diesel serves no environmental purpose except to please the environmentalist who are too ignorant to get a degree. A Cat on a normal gas powered auto has a catalyst inside like platinum, palladium, or rhodium. This catalyst converts harmful toxins like CO (carbon monoxide), hydrocarbons, or N (Nitrogen) in to less toxic compounds like CO2, O2, H2O. Now on a diesel the chemistry behind the formulation of diesel and the physics behind the internal combustion diesel engine dictate that these harmful toxins are not found in the exhaust of diesel engine. To go back to a gasoline-powered auto, they have what is called an O2 sensor before the Cat to determine the amount of oxygen in the exhaust. This can be used to defuel the engine and help the Cat do its job. Now you will notice that on our diesels there are no O2 sensor. If you also examine a Diesel Cat you will notice that is contains a bunch of screens and that is it. The reason for this design is to filter out the smoke that is coming out of a diesel. You see MOST environmentalists are ignorant (meaning uneducated) and believe more in what you can see instead of scientific fact. I have attended a green peace conference in Seattle WA and have heard that on diesels they think the smoke coming out of a diesel is the most toxic chemical known to man, when in actuality, the unseen emissions from a gas auto is. They also said that the amount of trash created by man is increasing the mass of the earth by 1 billion tons per year. How do you increase the mass of the Earth? Everything we have is made from the Earth. To move on, the Cat on a diesel serves no purpose except to keep the uneducated quiet. But I would highly recommend keeping the Cat on a Gas vehicle, it does serve it's purpose.
Senior User
Joined: Oct 2004
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From: FREELAND
I have a 04 6.0 with the cat on I was getting 12.5 mpg with a predator programer. then I put a MBRP turbo back with cat delete same programer now Im getting 18 mpg thats was doing 70mph towing a two place snowmobile trailer.
Elder User
Joined: Feb 2003
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Originally Posted by drtry10
Boy, have I been waiting for some idiot to say this!.........to filter out smoke..........
"Sales growth of diesel cars has raised concern on the possible health effects from the ultra-fine particulates in diesel emissions. All diesel-engined cars sold in Europe are now fitted with oxidation catalysts. Some, but not many, heavy-duty vehicles also use oxidation catalysts. Oxidation catalysts lower particulate mass by up to 50%, by destruction of the organic fraction of the particulate, as well as making significant reductions in CO, HC and the characteristic diesel odour. However, the number of particles is unchanged and issues associated with the effects of ultra-fine particulates remain unresolved."
Cats on diesels, though not a perfect solution to cleaning up diesel emissions and agreeably not the same as on gassers, DO serve a purpose.
You can believe what you wish.
Last edited by Btravelen; Jan 30, 2006 at 10:37 PM.
Senior User
Joined: Dec 2004
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From: Kenner, Louisiana
I took mine off to get the full sound of my mbrp exhaust. Truck runs fine. I noticed when I took the cat off it was already full of soot (15k miles). I would think after accumulating a lot of miles it would easily clog and hamper performance.
Elder User
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See the third pic here, and the reason for it. http://www.forddoctorsdts.com/photographs/index5.php
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Btravelen, I am not here to argue with you. But I would suggest taking a physics or chemistry class. Maybe Organic chemistry or particle physics. Both will enlighten you to the fact that the catalyst inside a catalytic converter is designed for the exhaust gasses of a gas engine and not diesel emissions. You can quote whatever you want from the internet, but keep in mind the internet has just as many personal beliefs as is does facts. I would suggest reading a physics book. You see the sustained high temp that a diesel cylinder is exposed to is greater then that of a gas engine. Although the temp is higher, it last for more time. The sustained high temp helps to effeciently burn most or all the diesel fuel. This reduces the amount of hydrocarbons, which is essentially unburnt, or partially burnt fuel. Todays diesels are more effecient then those from years ago, that is why you find newer diesels smoke less. Organic chemistry will help to to see that the chemical compound of Gas and diesel are different therefore when combustion happens, different emissions are the result. I do agree that diesel engines do give off more particulates then that of gas engines, but a catalytic converter is not the answer. Just for the record, I am an avid enviromentalist, and part of the Sierra Club here in California, so I am not one for destroying the enviroment. I just know that the majority of enviromentalist are one sided and do not listen to reason. I am for the successful and intelligent solution, not the quick fixes that look and sound ok but don't actually work. Now if you would like a detailled explanation to the physics behind the cat I would love to tell you. Just let me know.