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  #16  
Old 03-05-2010, 04:27 PM
richarddhoward richarddhoward is offline
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Default Re: gutting a cat

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Originally Posted by 00bamaranger View Post
as far as our trucks not putting out enough exhaust to get "stuck" in the cat, have you ever taken one apart and looked inside it? they are extremly restrictive. have you ever wondered why a cat has to have a heat shield, get under your truck after you drive it and the exhaust is still hot, the cat is a hell of alot hotter than the rest, from a thermodynamic point of view this means that the cat is taking alot of engery out of the system, in this case it is kenetic energy that the cat is taking out of the system slowing down the gas and creating more pressure of the engine side. and yes the engine does need some backpressure but the cat gives it more backpressure than it needs. and no mine wasnt stopped up when i took it out. i was running in with no cat for a while and decided to put a magnaflow highflow cat in because i didnt like the sound of it. when i put on the highflow cat my mpg went down but they were still higher than it was stock.
HAHAHAHAHAHAHA That's not true. The reason your cat is so much hotter is because of the chemical reaction of NOx gases and the precious metals in the catalytic converter changing the make up of the exhaust gases! Sorry to laugh but that's not how they work
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  #17  
Old 03-05-2010, 04:37 PM
00bamaranger 00bamaranger is offline
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Default Re: gutting a cat

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Originally Posted by richarddhoward View Post
HAHAHAHAHAHAHA That's not true. The reason your cat is so much hotter is because of the chemical reaction of NOx gases and the precious metals in the catalytic converter changing the make up of the exhaust gases! Sorry to laugh but that's not how they work
that is true the chemical reaction is part of the reason they get hot but the gas also has to be slowed down for the reaction to complete
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  #18  
Old 03-05-2010, 05:28 PM
Jp7 Jp7 is offline
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Default Re: gutting a cat

Quote:
have you ever taken one apart and looked inside it? they are extremly restrictive.
With a stock motor you are wrong, they are not restrictive. They are designed to keep the exhaust pulses moving at the high speed.


Quote:
the cat is a hell of alot hotter than the rest, from a thermodynamic point of view
The reaction is exothermic, which causes it to get warmer. It has nothing to due with backpressure.


Quote:
...yes the engine does need some backpressure...
No, it does not need any backpressure. Rookies confuse backpressure and exhaust gas speed all of the time.
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  #19  
Old 03-06-2010, 09:31 PM
00bamaranger 00bamaranger is offline
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Default Re: gutting a cat

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Originally Posted by Jp7 View Post
With a stock motor you are wrong, they are not restrictive. They are designed to keep the exhaust pulses moving at the high speed.




The reaction is exothermic, which causes it to get warmer. It has nothing to due with backpressure.




No, it does not need any backpressure. Rookies confuse backpressure and exhaust gas speed all of the time.

I am a senior majoring in mechanical engineering and i am taking intro to enviromental engineering and the design of catalytic converters was one of the first things we talked about this semester. your right the reaction is exothermic but the exhaust gases must be slowed down in order to achieve a complete reaction, creating friction which also causes it to get hot, so it is a combination of the reaction and the friction which causes it to get hot. part of the design is to slow the gases down. and yes an engine does need some backpressure to operate at maximum efficiency. exhaust gas speed and the volume of gas being moved (called the mass flow rate) and the design of the exhaust system, more specifically the drag of the system, contribute to the amount of backpressure. rookies get this confused about this all the time.
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  #20  
Old 03-07-2010, 01:52 AM
Jp7 Jp7 is offline
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Default Re: gutting a cat

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I am a senior majoring in mechanical engineering and i am taking intro to enviromental engineering and the design of catalytic converters was one of the first things we talked about this semester.
I graduated with my masters in ME in 2004, after 7 years of college and 7 years with the SAE formula car team. I've worked as a professional tuner for 3 years and I've been in the automotive field for 8 years. I've represented AEM at national events such as the North American International autoshow and I'm a certified AEM tuner specializing in Alcohol (Ethanol/Methanol) tuning for 2 years. My pride and joy achievement of late is a stock-turbo 421 whp IX I tuned for someone with absolutely no knock on only 93 (this is quite an achievement dealing with considerable amounts of heat and backpressure) ......... Since were talking credentials.

Quote:
....the reaction is exothermic but the exhaust gases must be slowed down in order to achieve a complete reaction, creating friction which also causes it to get hot, so it is a combination of the reaction and the friction which causes it to get hot. part of the design is to slow the gases down....
OEM's use a catalyst of wider diameter than the surrounding gas so that the flow isn't restricted as it passes in, and out of the brick. The catalysts are as close to the head as possible because the rate of the reaction is proportional to the square of the temperature and the hotter the flow, the faster it is. Turbulent flow exiting the catalyst is a difficult thing to design around, but is present primarily around high rpm (where you are not driving your ranger around) My primary research with this is with the Subaru EJ engine. I've probed the system in multiple places and compared catless and catalyzed exhaust and even in a high performance turbo engine, it makes no difference until you approach redline. The gain in removing the converter is in the fact you can increase timing and lean the mixture out because of the lack of backpressure when catless. If you don't have software to do this it is a big waste of time, and on a naturally aspirated engine even with the right software adjustments the gains are negligible on a stock engine with "street like" restrictive head(s). Making it "go fast" is 65% Software, 15% parts and 20% chemistry. (providing the parts are strong enough to keep things reliable)

Quote:
....an engine does need some backpressure to operate at maximum efficiency.
Backpressure is the enemy. Stock exhaust systems are designed for fast-flow at low rpms which leads to reasonable amounts of backpressure. It keeps the exhaust moving and a nice jump of torque in the everyday driving low rpm range. The exhaust you have that came with a converter was designed so that they pulses push and pull together. I've actually logged exhaust backpressure as a function of rpm over a run to see whats going on. Under high resolution you can see the individual pulses in the manifold at low rpm. Your engine (and all engines today) are tuned specifically for a basic configuration with a catalytic converter(s) .A good tuner with even a normally aspirated engine can adjust the maps to optimize the idle, low load and WOT portions of the maps to get benefit from any system, regardless of cat/no cat. The only real reason I see to remove a converter is the benifits from 'fun fuel' and drastic changes in maps unless you have a very modified engine, which basically no one on RF does. Now if you have a fully built racing engine with a CNC head, larger turbo, 500 lph fuel system with 150 lb injectors operating at 29psi daily the catalyst will cause a restriction. (like I do)
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People so often confuse "hating" with "knowing better".

Last edited by Jp7; 03-07-2010 at 03:18 AM.
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  #21  
Old 03-07-2010, 04:14 AM
SCRATCHBGONE SCRATCHBGONE is offline
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Default Re: gutting a cat

I took a broom stick to mine back in 99 no cel's no hp but better sound (headers through flowmaster)
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  #22  
Old 03-07-2010, 12:46 PM
Daedalus Daedalus is offline
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Default Re: gutting a cat

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Originally Posted by Jp7 View Post
I graduated with my masters in ME in 2004, after 7 years of college and 7 years with the SAE formula car team. I've worked as a professional tuner for 3 years and I've been in the automotive field for 8 years. I've represented AEM at national events such as the North American International autoshow and I'm a certified AEM tuner specializing in Alcohol (Ethanol/Methanol) tuning for 2 years. My pride and joy achievement of late is a stock-turbo 421 whp IX I tuned for someone with absolutely no knock on only 93 (this is quite an achievement dealing with considerable amounts of heat and backpressure) ......... Since were talking credentials.


Damit. I was looking for an "owned" smiley for this quote but we don't have one...
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  #23  
Old 03-07-2010, 02:51 PM
richarddhoward richarddhoward is offline
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Default Re: gutting a cat

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Originally Posted by Daedalus View Post
Damit. I was looking for an "owned" smiley for this quote but we don't have one...
x2 lol
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I think Henry just shit himself
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  #24  
Old 03-07-2010, 03:09 PM
nosdsm3 nosdsm3 is offline
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Default Re: gutting a cat

If you want to just test it out you could just get a test pipe. Then you can see the results for yourself at a 20-30 dollar price tag.
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  #25  
Old 03-07-2010, 09:14 PM
00bamaranger 00bamaranger is offline
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Default Re: gutting a cat

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Originally Posted by Jp7 View Post
I graduated with my masters in ME in 2004, after 7 years of college and 7 years with the SAE formula car team. I've worked as a professional tuner for 3 years and I've been in the automotive field for 8 years. I've represented AEM at national events such as the North American International autoshow and I'm a certified AEM tuner specializing in Alcohol (Ethanol/Methanol) tuning for 2 years. My pride and joy achievement of late is a stock-turbo 421 whp IX I tuned for someone with absolutely no knock on only 93 (this is quite an achievement dealing with considerable amounts of heat and backpressure) ......... Since were talking credentials.



well you do have much much higher credentials than me so i guess ill have to take your word on it, but regardless i did have positve results on my truck when i took mine off, i never had it on a dyno or anything just the seat of the pants dyno haha, it wasnt a 20 hp gain or anything but maybe 5-10hp (i never said there were big gains but noticable) but i did pick up a little extra mpg. these were my results so im not going to argue about that because this is not a theory but what actually happened for me. but ill take your word on the science behind it because you would know alot more about it than me. where did you get your bs and masters from? here we cant work on the sae formula car team until junior year and if you did it for 7 years i guess you did it as a freshman.
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  #26  
Old 03-07-2010, 09:18 PM
00bamaranger 00bamaranger is offline
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Default Re: gutting a cat

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Originally Posted by Jp7 View Post
My pride and joy achievement of late is a stock-turbo 421 whp IX I tuned for someone with absolutely no knock on only 93 (this is quite an achievement dealing with considerable amounts of heat and backpressure) ......... Since were talking credentials.


oh and i forgot to say that is impressive
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  #27  
Old 03-07-2010, 09:27 PM
Jp7 Jp7 is offline
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Default Re: gutting a cat

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Originally Posted by 00bamaranger View Post
well you do have much much higher credentials than me so i guess ill have to take your word on it, but regardless i did have positve results on my truck when i took mine off, i never had it on a dyno or anything just the seat of the pants dyno haha, it wasnt a 20 hp gain or anything but maybe 5-10hp (i never said there were big gains but noticable) but i did pick up a little extra mpg. these were my results so im not going to argue about that because this is not a theory but what actually happened for me. but ill take your word on the science behind it because you would know alot more about it than me. where did you get your bs and masters from? here we cant work on the sae formula car team until junior year and if you did it for 7 years i guess you did it as a freshman.
Your mileage and power are both highly dependent on the state of your fuel trims. Every vehicle responds differently to modifications, I've seen some pretty strange things. This is why I never modify anything on a vehicle that I don't have the software to make proper adjustments. I went to the State University of New York @ Buffalo. I knew I wanted to join the formula team even when I was in high school and I was even able to use a project working on a Engine swap for college credits during my senior year.
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Originally Posted by FireRanger View Post
I'm dying to see this at night. Someone go tell the sun to give up already.
Quote:
Originally Posted by beef08 View Post
Your the man, you bring our dreams to a reality within the lighting spectrum
Quote:
Originally Posted by BCobe View Post
Jp7 you always do AMAZING work! Hats off to you sir
Quote:
Originally Posted by FireRanger View Post
People so often confuse "hating" with "knowing better".
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  #28  
Old 03-07-2010, 09:41 PM
00bamaranger 00bamaranger is offline
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Default Re: gutting a cat

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Originally Posted by Jp7 View Post
Your mileage and power are both highly dependent on the state of your fuel trims. Every vehicle responds differently to modifications, I've seen some pretty strange things. This is why I never modify anything on a vehicle that I don't have the software to make proper adjustments. I went to the State University of New York @ Buffalo. I knew I wanted to join the formula team even when I was in high school and I was even able to use a project working on a Engine swap for college credits during my senior year.
yeah my little 4 cylinder doesnt make much power so every little bit helps. and youre right every vehicle resonds differently to mods, on another thread someone was askin about the airaid throttle body spacer that i have on my truck and they swore up and down that it didnt work for them on their 3.0 and it actually hurt power and mpg, but i had good results with it on mine. yeah i wish i had all the software to tune myself, i will one day hopefully. i wish i could done an engine swap for college credit but to my knowledge alabama doesnt do anything like that.
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  #29  
Old 03-07-2010, 10:08 PM
FireRanger FireRanger is offline
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Default Re: gutting a cat

Humph. I thought this was a thread about Chinese food.
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  #30  
Old 03-07-2010, 10:20 PM
00bamaranger 00bamaranger is offline
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Default Re: gutting a cat

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Humph. I thought this was a thread about Chinese food.
haha thats funny
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