Looking for dyno #'s without cats
Thread Starter
Melting Slicks
Joined: Jul 2005
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From: Bardstown Kentucky
Looking for dyno #'s without cats
Does anyone have dyno proven results with and without cats? I have recently removed my cats and installed an x pipe. I am wondering what this would have done to my car as far as performance goes. I dont want to lose torque, but it seems the mufflers would be adequate back pressure to keep my torque numbers where they are. Thanks for any help!
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From: San Pedro CA
geez... you knew this was coming... so why in the hell did you remove your cats, just to pollute the air we breathe, for a lousy 5~10 hp?
I cannot justify it, and I will berate, belittle and guilt those that do until they realize it's wrong.
I cannot justify it, and I will berate, belittle and guilt those that do until they realize it's wrong.
Safety Car
Joined: Sep 2003
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From: Hayward CA
Originally Posted by bogus
geez... you knew this was coming... so why in the hell did you remove your cats, just to pollute the air we breathe, for a lousy 5~10 hp?
I cannot justify it, and I will berate, belittle and guilt those that do until they realize it's wrong.
I cannot justify it, and I will berate, belittle and guilt those that do until they realize it's wrong.
Tell us how you really feel
That being said...... on a stock car, you'd be lucky to see 5 hp. It's just louder, and more noisey.
Team Owner
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From: altered state
St. Jude Donor '05
Might give you 5-10hp or so.
btw, Wecome to the forum
"and I will berate, belittle and guilt those that do until they realize it's wrong."
Isn't that against forum rules?
btw, Wecome to the forum
"and I will berate, belittle and guilt those that do until they realize it's wrong."
Isn't that against forum rules?
Last edited by cv67; Oct 19, 2005 at 12:43 PM.
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Originally Posted by bogus
I cannot justify it, and I will berate, belittle and guilt those that do until they realize it's wrong.
On second thought, NOT!
Your constant rant about this subject is becoming very annoying.
My 86 was catless and ran much better (SOTP) without than with.
Last edited by JrRifleCoach; Oct 19, 2005 at 04:44 PM.
Le Mans Master
Joined: Apr 2005
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From: Scarborough ONTARIO
Originally Posted by 95BlueBomber
Does anyone have dyno proven results with and without cats? I have recently removed my cats and installed an x pipe. I am wondering what this would have done to my car as far as performance goes. I dont want to lose torque, but it seems the mufflers would be adequate back pressure to keep my torque numbers where they are. Thanks for any help!
with hollow cat, tpis flowmaster II 3", hooker headers got
277 RH and 398 Rt (note its 3" cat back too).
The car now has Tpis RT cat but dont know numbers but by driving not much diff compared to hollow cat, with RT cat no resonance, no burning eyes if standing rear of car and less noise at idle but noise level pretty much same w/wo cat at WOT.
When i had a hollow cat for few days i observed resonance at 1600 rpm low speed infact my hand was little shaky feel.
After RT cat no resonance at all at all rpm a nice crisper sound at idle and low speed but at wot it sream.
Drifting
Joined: Jun 2002
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From: Savannah Ga.
Originally Posted by bogus
geez... you knew this was coming... so why in the hell did you remove your cats, just to pollute the air we breathe, for a lousy 5~10 hp?
I cannot justify it, and I will berate, belittle and guilt those that do until they realize it's wrong.
I cannot justify it, and I will berate, belittle and guilt those that do until they realize it's wrong.
..................... He's not the first one to do it , and he want be the last.....no need to berate or belittle anyone.....just state your opinion and be done with it!!
Thread Starter
Melting Slicks
Joined: Jul 2005
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From: Bardstown Kentucky
Bogus.... I guess you have serious problems with drag cars and pre emissions cars. Oh well. Hope the ozone layer don't collapse on you cause I'm burning a little more fuel.
I was just hoping to not lose torque with out my cats, thanks for the info sami! Seems to have helped a little. I dont really drive this car on the street much anymore, so the increase in noise hasnt bothered me so far. Now the fumes behind the car are very strong. Again, nothing I cant deal with.
I am looking at heads and cam this winter and I heard that would help with the fuel smell. I guess if you go with a little bigger intake valve and leaned it out a little it would help. Without the cats though I keep thinking my car is running rich. I got a wideband 02 going in tonight.
Thanks again!
The Bomber
I was just hoping to not lose torque with out my cats, thanks for the info sami! Seems to have helped a little. I dont really drive this car on the street much anymore, so the increase in noise hasnt bothered me so far. Now the fumes behind the car are very strong. Again, nothing I cant deal with.
I am looking at heads and cam this winter and I heard that would help with the fuel smell. I guess if you go with a little bigger intake valve and leaned it out a little it would help. Without the cats though I keep thinking my car is running rich. I got a wideband 02 going in tonight.
Thanks again!
The Bomber
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Removing cats on the LT engines doesnt free up much power, they are pretty free-flowing already. Lingenfelter's book says he usually saw only a 5hp difference on a dynojet.
L98 is a different story.
L98 is a different story.
Le Mans Master
Joined: Apr 2000
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From: Manassas VA
I dont have dyno no's but I can tell you with mine I seen about 1tenth second difference on our local 1/8 mile track. But in all fairness Im not sure the cats were causing all of it. I had some bad plugs that I changed at the same time. Im still playing with exhaust, and I can tell you that I see no performance difference with the magnaflows compared to the stock mufflers.
Drifting
Joined: May 2003
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From: Charlotte NC
St. Jude Donor '05
One thing to think about to those who feel guilt free with thier cat cars.
How are you helping? Your still driving a vette and probally aggressively at that which waste fuel, tire life (part petrolium product), etc. Your still using fuel , your still polluting and more than you could otherwize be doing by driving a EVEN MORE fuel effiecient vehicle or using public transportation.
Heres my take on it, I drive my hotrod less than 3-4k yearly. Its for enjoyment only.. I have a seperate vehicle for day-to-day driving...Reason? well... 1 for comfort and 2. because i'm both enviromentally and economically aware of our situation as a nation. Its not my pocket that hurts when I waste gas but its the pocket of the entire nation. If I where to drive that car to work everyday I would be really concerned with fuel mileage, emmissions, tire pressure, tire wears, etc. but I do not, so I am not.
How are you helping? Your still driving a vette and probally aggressively at that which waste fuel, tire life (part petrolium product), etc. Your still using fuel , your still polluting and more than you could otherwize be doing by driving a EVEN MORE fuel effiecient vehicle or using public transportation.
Heres my take on it, I drive my hotrod less than 3-4k yearly. Its for enjoyment only.. I have a seperate vehicle for day-to-day driving...Reason? well... 1 for comfort and 2. because i'm both enviromentally and economically aware of our situation as a nation. Its not my pocket that hurts when I waste gas but its the pocket of the entire nation. If I where to drive that car to work everyday I would be really concerned with fuel mileage, emmissions, tire pressure, tire wears, etc. but I do not, so I am not.
Last edited by Alvin; Oct 19, 2005 at 05:07 PM.
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In 1991 no-one complained to the EPA when Sadam lit up the oil wells. In one second a burning oil well produces more smog than a 72 big block corvette using leaded gas in a lifetime. Just put the cats back for the "smog check" 
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From: SE NY
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Well another consideration is to think of how many Vettes there are on the roads, how much they are actually driven and then consider the number of gas-guzzling SUVs out there today.
And our government, with their usual "infinite wisdom" continues to promote them by not hitting them with the gas-guzzler tax that would be imposed on Vettes if they got anyway near such lousy mileage. Meanwhile they are now telling us to lower our T-stats and take public transportation.
OK back on topic. If you were running FL headers on a well tuned engine you would gain by reducing back pressure, to a point. Look at most engine dyno pulls and ask how are they done. I think the answer is (usually) with FL headers and a length of open pipe on the end of each collector.
But in the real world, if you live in an area where emisions are a serious consideration, a pair of hi-flow cats and mufflers will not reduce peak power appreciably until you get into the 500chp range.
And our government, with their usual "infinite wisdom" continues to promote them by not hitting them with the gas-guzzler tax that would be imposed on Vettes if they got anyway near such lousy mileage. Meanwhile they are now telling us to lower our T-stats and take public transportation.
OK back on topic. If you were running FL headers on a well tuned engine you would gain by reducing back pressure, to a point. Look at most engine dyno pulls and ask how are they done. I think the answer is (usually) with FL headers and a length of open pipe on the end of each collector.
But in the real world, if you live in an area where emisions are a serious consideration, a pair of hi-flow cats and mufflers will not reduce peak power appreciably until you get into the 500chp range.
Le Mans Master
Joined: Dec 2002
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From: Seattle Area WA
Here is a comparison on w/cats w/o cats I just stumbled on today...
And this is done on an engine dyno at what appears identicle atmospheric conditions, so yeah, this gets about as good as it gets....
FYI, I have LPE LTs into a gutted cat and out the Magnaflow catback. Sounds awesome! But I have a cat I might put on soon anyway to see if the back pressure helps power.
P.S. I ride a road bike...as in a bicycle...10 months out of every year for my ONLY mode of transportation.
http://dtcc.cz28.com/gta/dyno.htm
And this is done on an engine dyno at what appears identicle atmospheric conditions, so yeah, this gets about as good as it gets....
FYI, I have LPE LTs into a gutted cat and out the Magnaflow catback. Sounds awesome! But I have a cat I might put on soon anyway to see if the back pressure helps power.
P.S. I ride a road bike...as in a bicycle...10 months out of every year for my ONLY mode of transportation.
http://dtcc.cz28.com/gta/dyno.htm
Last edited by USAsOnlyWay; Oct 20, 2005 at 04:41 PM.
Melting Slicks
Joined: Feb 2005
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From: Sebastian Florida
St. Jude Donor '06
Originally Posted by USAsOnlyWay
Here is a comparison on w/cats w/o cats I just stumbled on today...
And this is done on an engine dyno at what appears identicle atmospheric conditions, so yeah, this gets about as good as it gets....
And this is done on an engine dyno at what appears identicle atmospheric conditions, so yeah, this gets about as good as it gets....
I am with Bogus, Some of you are acting like 2yr olds. 'Saddam set the wells on fire' or 'What about those big SUV's', how old are you???
Those SUV's might suck gas, but WHAT does that have to do with what Bogus said?
It will put out a lot less pollutants than your non cat Vette will and for what 5hp maybe!!
But cats are not that restrictive, if you feel you the need to relieve some back pressure, why don't you gut out your muffler?
This is the one site were you have to have a flame suit on and a fire truck standing by, if you make a comment somebody doesn't like!!
And yes, I called 911, before sending this post!!
Team Owner
Joined: Aug 2000
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From: San Pedro CA
Originally Posted by JrRifleCoach
Don't hold back now. Tell us how you really feel.
On second thought, NOT!
Your constant rant about this subject is becoming very annoying.
My 86 was catless and ran much better (SOTP) without than with.
On second thought, NOT!
Your constant rant about this subject is becoming very annoying.
My 86 was catless and ran much better (SOTP) without than with.
If I stop, then others will feel its ok, and will do this without any other input.
Get used to it.
Team Owner
Joined: Aug 2000
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From: San Pedro CA
Originally Posted by redcorvettedave
..................... He's not the first one to do it , and he want be the last.....no need to berate or belittle anyone.....just state your opinion and be done with it!!
There are many problems with our global environment, why can't we, as educated people, take a moment and be responsable ADULTS about the problems and do the little bit we can.
If you can't be grown up about it, please, forward me an air filter and O2 tank, cause if you get your wish, our air will be **** again within 10 years.
I don't want that and I suspect neither do your kids.