deleting cats from stock headers question
06-13-14, 12:15 PM
#16
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I'll be your dyno....
Me and Slay raced not to long ago. We both data logged our cars, wot runs and A/F mixtures were great.
We raced from a 40mph roll till 160mph. We were head to head. At 90, 120, 140mph I jumped a foot at each. At 160mph I was only up by 3 tiny feet.
My car: afe filter, ppe header, isa cat back, iss scoops (a whole lotta $)
Slays: gutted primary cats w/ ppe 02 conditioner, replaced mufflers & secondary cats with straight pipes (he saved a lot of $, lol)
Me and Slay raced not to long ago. We both data logged our cars, wot runs and A/F mixtures were great.
We raced from a 40mph roll till 160mph. We were head to head. At 90, 120, 140mph I jumped a foot at each. At 160mph I was only up by 3 tiny feet.
My car: afe filter, ppe header, isa cat back, iss scoops (a whole lotta $)
Slays: gutted primary cats w/ ppe 02 conditioner, replaced mufflers & secondary cats with straight pipes (he saved a lot of $, lol)
What would be a truly interesting (but expensive) experiment would be to put the OEM cats after a set of headers and see what happens. It would not surprise me if the header's gains disappeared with the OEM cats back in the system.
If you do I have a bridge you might be interested in.
06-13-14, 03:44 PM
#18
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I ran a cryogenic gas separation lab. I know a little bit about gas behavior. Many times what looks good isn't significantly better than something that doesn't look good. This is why we test. Honestly I don't care about what it looks like. I'd say the results speak for themselves. Car with gutted cats hangs even with car with headers at WOT. What else do you need to be convinced?
06-13-14, 04:15 PM
#19
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Do you really consider 1 roll race to be definite proof one way or another Though?
I have done my fair share of roll racing and two cars just about never start at the exact same time. Those fractions of a second coupled with the fact we are talking a very small power difference here as it is, makes it hard to draw any conclusion.
You can't expect one car to run away from another when there's maybe 10-15whp difference on paper. We can't really quantify what Pulling "3ft" means in terms of performance.
I'd agree that what "seems" like it should work isn't always the case though. We don't really have any definitive proof one way or another vs gutted stock headers. All we know is that aftermarket headers make more power than untouched factory headers.
I'd love to see what both trap on the same day, given similar weight, and tire/wheel setups.
I have done my fair share of roll racing and two cars just about never start at the exact same time. Those fractions of a second coupled with the fact we are talking a very small power difference here as it is, makes it hard to draw any conclusion.
You can't expect one car to run away from another when there's maybe 10-15whp difference on paper. We can't really quantify what Pulling "3ft" means in terms of performance.
I'd agree that what "seems" like it should work isn't always the case though. We don't really have any definitive proof one way or another vs gutted stock headers. All we know is that aftermarket headers make more power than untouched factory headers.
I'd love to see what both trap on the same day, given similar weight, and tire/wheel setups.
06-13-14, 04:31 PM
#20
Sonicblu is my Uncle. This is something me and him have spoke about and a couple of questions and concerns were brought up with MRslayXX . This is something that he will try to see if there is a significant power gain. Also from speaking with mrslay; he mentioned that the PPE sim will not work. However he did mention that the SIkky sim will work so that a CEL will not pop up. We will try this and see what are the gains between the current set up vs deleted primary cats in the next few days once he gets the sim.
06-13-14, 05:38 PM
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Do you really consider 1 roll race to be definite proof one way or another Though?
I have done my fair share of roll racing and two cars just about never start at the exact same time. Those fractions of a second coupled with the fact we are talking a very small power difference here as it is, makes it hard to draw any conclusion.
You can't expect one car to run away from another when there's maybe 10-15whp difference on paper. We can't really quantify what Pulling "3ft" means in terms of performance.
I'd agree that what "seems" like it should work isn't always the case though. We don't really have any definitive proof one way or another vs gutted stock headers. All we know is that aftermarket headers make more power than untouched factory headers.
I'd love to see what both trap on the same day, given similar weight, and tire/wheel setups.
I have done my fair share of roll racing and two cars just about never start at the exact same time. Those fractions of a second coupled with the fact we are talking a very small power difference here as it is, makes it hard to draw any conclusion.
You can't expect one car to run away from another when there's maybe 10-15whp difference on paper. We can't really quantify what Pulling "3ft" means in terms of performance.
I'd agree that what "seems" like it should work isn't always the case though. We don't really have any definitive proof one way or another vs gutted stock headers. All we know is that aftermarket headers make more power than untouched factory headers.
I'd love to see what both trap on the same day, given similar weight, and tire/wheel setups.
Who knows what the dyno difference would be? Dynos are cool, but just as lobux said, what looks good might not actually be better. If any local Fs want to try out so we can learn more just send me a pm.
06-13-14, 06:01 PM
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I would consider the fact that my old car probably still has the fastest 1/4 time in America today. Even with the super high heat and humidity we have in south Florida, the car was still able to run well and set records. My current ISF will run 10s later this year and it's going to utilizing the exact same exhaust setup that it has today.
Who knows what the dyno difference would be? Dynos are cool, but just as lobux said, what looks good might not actually be better. If any local Fs want to try out so we can learn more just send me a pm.
Who knows what the dyno difference would be? Dynos are cool, but just as lobux said, what looks good might not actually be better. If any local Fs want to try out so we can learn more just send me a pm.
Once you start adding spray, and other variables we are straying further from the question at hand. Does gutted stock headers, give similar power(or maybe greater power) to aftermarket headers on an N/A, non power adder setup? That is what most people seem to want to know.
Saying the car will run 10's doesn't mean X is better than Y. It just means it will run 10's with a given setup.
And to clarify, I have no bias one way or another. I am all for information. I would love to see a well organized test or A-B comparison. If at any point I feel confident the gutted stockers would out perform PPE's I would gladly run that setup.
If I were to speculate/hypothesize on the topic, I could see that maybe removing the cats frees up enough flow to make more power over stock, while keeping just enough back-pressure to give more area under the curve than an aftermarket header provides. So "maybe" gutted stock manifolds will give slightly less peak power, however give a broader powerband. I have no clue, but I have seen this exact thing on other platforms.
Last edited by Cronic; 06-13-14 at 06:04 PM.
06-13-14, 07:27 PM
#26
Not that my opinion matters much... but I honestly always thought it was the emissions and not so much the pipe diameters of the exhaust that was the problem. if you think about it, the exhaust valves are definitely SMALLER in diameter than the "log" style headers. Did you actually examine the stock cats? They are TIGHTLY packed.
Knowing what I know now, I would've tried gutting them with conditioners also. Oh well. Too late.
Knowing what I know now, I would've tried gutting them with conditioners also. Oh well. Too late.
06-13-14, 07:45 PM
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Your car would make one of the better test subjects since you are pretty in tune with what it traps, etc. Swap in some gutted stockers, and have at it.
06-13-14, 08:03 PM
#28
Taking the PPE headers out and putting back in the stock headers with gutted cats goes for about 600-1000 labor alone. After getting black ceramic coated headers (1500), labor (1,000), and new A/F sensors and gaskets (400?) and them some CEL repairs, I'm a lil over 3K in headers. I'm not about to pay another 1000 to go back to stock minus cats LOL.
I'm keeping my stock headers in case I might go back to stock down the road for emissions or sales purposes.
I'm keeping my stock headers in case I might go back to stock down the road for emissions or sales purposes.
06-14-14, 09:46 PM
#30
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Many times what looks good isn't significantly better than something that doesn't look good. This is why we test. Honestly I don't care about what it looks like. I'd say the results speak for themselves. Car with gutted cats hangs even with car with headers at WOT. What else do you need to be convinced?
Do you really consider 1 roll race to be definite proof one way or another Though?
I have done my fair share of roll racing and two cars just about never start at the exact same time. Those fractions of a second coupled with the fact we are talking a very small power difference here as it is, makes it hard to draw any conclusion.
I have done my fair share of roll racing and two cars just about never start at the exact same time. Those fractions of a second coupled with the fact we are talking a very small power difference here as it is, makes it hard to draw any conclusion.
Why? Keep it. Works well
