bigger cat or test pipe?
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From: Canada City
bigger cat or test pipe?
hmmm..gonna get a 3" downpipe.
what should I do. get a bigger cat?? test pipe?? or just have the exhaust right off the header????
opinions wanted pls
what should I do. get a bigger cat?? test pipe?? or just have the exhaust right off the header????
opinions wanted pls
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From: San Francisco, CA
Re: bigger cat or test pipe? (Quaalude)
when i took out my random 3" cat & replaced it with a 3" test pipe, i gained 4psi of boost at the same boost controller setting & the turbo spooled soooo much faster.
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From: NOR CAL, US
Re: bigger cat or test pipe? (qwkteg125)
When i had my stock exhaust i had about 7 psi on my controller then i went with my open 2.5 inch downpipe it also went about 3 to 4 psi higher with the same setting...
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From: Denver, PA, 17517
Re: bigger cat or test pipe? (CM-R)
Sorry but I'm still learning, a test pipe is just a pipe that goes instead of the car right, doesn't it also have a spot for the 02 sensor so the check engine light wont' go on?
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From: TheNine2Five, Ca, USA
Re: bigger cat or test pipe? (jamal-188)
Sorry but I'm still learning, a test pipe is just a pipe that goes instead of the car right, doesn't it also have a spot for the 02 sensor so the check engine light wont' go on?
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From: Markham, Ontario, Canada
Re: bigger cat or test pipe? (Bryson)
Only run a 3" exhaust if your making 400hp or better. 2 1/2 is more then enough, and flows more efficently.Unless your running open downpipe.
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From: Denver, PA, 17517
Re: bigger cat or test pipe? (MIKES)
Only run a 3" exhaust if your making 400hp or better. 2 1/2 is more then enough, and flows more efficently.Unless your running open downpipe.
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From: Canada City
Re: bigger cat or test pipe? (jamal-188)
you sure?
plenty of guys making 250 whp or so run with a 3" and before they had smaller and made less power..
ahaha at that huge *** cat.i know i dont have a header..i rushed typing that. sorry.
ive got a greddy evo and was really debating whether or not to switch to a 3" thermal orjust stay greddy. i would go thermal but I LOVE the way the greddy looks. awesome! its like a supra exhaust
so...either get the thermal( so i will need a 3" downpipe) or stay with the evo and get a 2.5" down pipe.
what do you suggest?
plenty of guys making 250 whp or so run with a 3" and before they had smaller and made less power..
ahaha at that huge *** cat.i know i dont have a header..i rushed typing that. sorry.
ive got a greddy evo and was really debating whether or not to switch to a 3" thermal orjust stay greddy. i would go thermal but I LOVE the way the greddy looks. awesome! its like a supra exhaust
so...either get the thermal( so i will need a 3" downpipe) or stay with the evo and get a 2.5" down pipe.what do you suggest?
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From: I heart tool, US
Re: bigger cat or test pipe? (MIKES)
Dumbass.
You shouldn't go around telling people this.
with a turbo THERE ARE NO DOWNFALLS for using a HUGE exhuast.
I mean there is no notible difference in power between a 3" and a 8" exhuast.
The exhuast turbine, is such a restriction it self, that a bigger exhuast will not REDUCE power.
Less back pressure the better, and Turbo's do not rely on gas velocity in exhuast as N/A engines do.
You shouldn't go around telling people this.
with a turbo THERE ARE NO DOWNFALLS for using a HUGE exhuast.
I mean there is no notible difference in power between a 3" and a 8" exhuast.
The exhuast turbine, is such a restriction it self, that a bigger exhuast will not REDUCE power.
Less back pressure the better, and Turbo's do not rely on gas velocity in exhuast as N/A engines do.
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From: Portland, OR
Re: bigger cat or test pipe? (Bryson)
Dumbass.
You shouldn't go around telling people this.
with a turbo THERE ARE NO DOWNFALLS for using a HUGE exhuast.
I mean there is no notible difference in power between a 3" and a 8" exhuast.
The exhuast turbine, is such a restriction it self, that a bigger exhuast will not REDUCE power.
Less back pressure the better, and Turbo's do not rely on gas velocity in exhuast as N/A engines do.
You shouldn't go around telling people this.
with a turbo THERE ARE NO DOWNFALLS for using a HUGE exhuast.
I mean there is no notible difference in power between a 3" and a 8" exhuast.
The exhuast turbine, is such a restriction it self, that a bigger exhuast will not REDUCE power.
Less back pressure the better, and Turbo's do not rely on gas velocity in exhuast as N/A engines do.
It certainly seems to be the case for NA cars that if you go to too big of a pipe that you will lose low-end power. The exhaust gas velocity will be too low and it won't be exiting fast enough at low revs...
It would seem with a turbo that you would get more power with a bigger pipe...
HOWEVER, that doesn't seem to be the reality with turbos, but don't take my word for it.
If you'd like to refer to page 132 in Maximum Boost, it reads; '"The larger the better" is not the case.'...furthermore...on page 133 you see a graph that shows that a 3" exhaust will not hamper flow until over 700hp it reads '"The larger the better" is not the case.' Corky Bell says: That the exhaust diameter should be 10% more than the turbine outlet...so, if it's ~2 inches, 2.25 would be good for your exhaust pipe.
I know you know some sh*t (possibly more than me) and that's cool, but you really shouldn't call someone a dumbass, when you aren't on top of the game. Just keep it cool man.
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From: Zoo York
Re: bigger cat or test pipe? (ion_four)
Dumbass.
You shouldn't go around telling people this.
with a turbo THERE ARE NO DOWNFALLS for using a HUGE exhuast.
I mean there is no notible difference in power between a 3" and a 8" exhuast.
The exhuast turbine, is such a restriction it self, that a bigger exhuast will not REDUCE power.
Less back pressure the better, and Turbo's do not rely on gas velocity in exhuast as N/A engines do.
dumbass?...anyway...
It certainly seems to be the case for NA cars that if you go to too big of a pipe that you will lose low-end power. The exhaust gas velocity will be too low and it won't be exiting fast enough at low revs...
It would seem with a turbo that you would get more power with a bigger pipe...
HOWEVER, that doesn't seem to be the reality with turbos, but don't take my word for it.
If you'd like to refer to page 132 in Maximum Boost, it reads; '"The larger the better" is not the case.'...furthermore...on page 133 you see a graph that shows that a 3" exhaust will not hamper flow until over 700hp it reads '"The larger the better" is not the case.' Corky Bell says: That the exhaust diameter should be 10% more than the turbine outlet...so, if it's ~2 inches, 2.25 would be good for your exhaust pipe.
I know you know some sh*t (possibly more than me) and that's cool, but you really shouldn't call someone a dumbass, when you aren't on top of the game. Just keep it cool man.
You shouldn't go around telling people this.
with a turbo THERE ARE NO DOWNFALLS for using a HUGE exhuast.
I mean there is no notible difference in power between a 3" and a 8" exhuast.
The exhuast turbine, is such a restriction it self, that a bigger exhuast will not REDUCE power.
Less back pressure the better, and Turbo's do not rely on gas velocity in exhuast as N/A engines do.
dumbass?...anyway...
It certainly seems to be the case for NA cars that if you go to too big of a pipe that you will lose low-end power. The exhaust gas velocity will be too low and it won't be exiting fast enough at low revs...
It would seem with a turbo that you would get more power with a bigger pipe...
HOWEVER, that doesn't seem to be the reality with turbos, but don't take my word for it.
If you'd like to refer to page 132 in Maximum Boost, it reads; '"The larger the better" is not the case.'...furthermore...on page 133 you see a graph that shows that a 3" exhaust will not hamper flow until over 700hp it reads '"The larger the better" is not the case.' Corky Bell says: That the exhaust diameter should be 10% more than the turbine outlet...so, if it's ~2 inches, 2.25 would be good for your exhaust pipe.
I know you know some sh*t (possibly more than me) and that's cool, but you really shouldn't call someone a dumbass, when you aren't on top of the game. Just keep it cool man.
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Joined: Aug 2000
Posts: 3,605
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From: Japan Dammit Japan
Re: bigger cat or test pipe? (ek9t)
Corky Bell.. Porky Smell 
Anyway, a 2.5" dp with a 3" exhaust and free flowing gato (cat) is plenty for a sub 400hp Honda. I will be using a 60mm to 70mm dp and 80mm exhaust with my new setup. It's impossible to use piping larger than 60mm for the first 3 or 4 inches if you have a 4 bolt T3 ex housing.
Oh yeah, Too big of an exhaust/dp can harm hp production. Option Magazine proved this a couple years ago with one of their Muffler test. Test car was a SR20DET powered RPS13 180SX with a cpu tune for 1.2bar, 76mm exhaust, 60mm dp, 300ZX air flow meter, free flowing exhaust, 550cc injectors and SR20DET powered RNN14 Pulsar GTiR turbo.
Going from a 76mm exhaust to an 80mm N1 type exhaust netted about 10hp across the board. Boost spiked by .2 bar with a 76mm exhaust/76mm dp combo and sacrificed some lowend hp and torque below 4500rpm eventhough the car screamed like a monkey on bad speed they said it didn't feel as good as the 76mm ex/60mm dp setup. The 80mm/76mm dp setup made the power curve peakier moved the torque peak higher and produced a higher Hp number. A "RACE ONLY" stepped 76mm/85mm dp with 90mm Ti exhaust made the lil" turbo lazy. Actually the turbo would over spin and creep past it's efficiency range with this setup. There were double digit power loses on the lowend and the turbo would over overspin right before redline. The CPU was retuned with each change.
Not every turbo will benefit from "OVER sized piping. There are many factors to consider.. turbo size, engine flow capacity, engine effective power range and boosted power range, dp angular restrictions (bends) and many other things. If you are not doing full race duty you should keep the dp moderately sized since it will help regulate lowend power building. Unlike street cars race cars do not worry about driving around thru towns that have stop lights, speed limits and Sunday drivers cruising the 'ville 24/7.
Stop calling people dumbasses and quoting things from Porky Smell that you obviously do not understand! Rather than quote (or misquote) your hero give examples that people WILL understand.
One more thing, the SR20DET upgrade kit that I conjoured up for a friend produced 298whp with a 60mm dp and 76mm.
Anyway, a 2.5" dp with a 3" exhaust and free flowing gato (cat) is plenty for a sub 400hp Honda. I will be using a 60mm to 70mm dp and 80mm exhaust with my new setup. It's impossible to use piping larger than 60mm for the first 3 or 4 inches if you have a 4 bolt T3 ex housing.
Oh yeah, Too big of an exhaust/dp can harm hp production. Option Magazine proved this a couple years ago with one of their Muffler test. Test car was a SR20DET powered RPS13 180SX with a cpu tune for 1.2bar, 76mm exhaust, 60mm dp, 300ZX air flow meter, free flowing exhaust, 550cc injectors and SR20DET powered RNN14 Pulsar GTiR turbo.
Going from a 76mm exhaust to an 80mm N1 type exhaust netted about 10hp across the board. Boost spiked by .2 bar with a 76mm exhaust/76mm dp combo and sacrificed some lowend hp and torque below 4500rpm eventhough the car screamed like a monkey on bad speed they said it didn't feel as good as the 76mm ex/60mm dp setup. The 80mm/76mm dp setup made the power curve peakier moved the torque peak higher and produced a higher Hp number. A "RACE ONLY" stepped 76mm/85mm dp with 90mm Ti exhaust made the lil" turbo lazy. Actually the turbo would over spin and creep past it's efficiency range with this setup. There were double digit power loses on the lowend and the turbo would over overspin right before redline. The CPU was retuned with each change.
Not every turbo will benefit from "OVER sized piping. There are many factors to consider.. turbo size, engine flow capacity, engine effective power range and boosted power range, dp angular restrictions (bends) and many other things. If you are not doing full race duty you should keep the dp moderately sized since it will help regulate lowend power building. Unlike street cars race cars do not worry about driving around thru towns that have stop lights, speed limits and Sunday drivers cruising the 'ville 24/7.
Stop calling people dumbasses and quoting things from Porky Smell that you obviously do not understand
! Rather than quote (or misquote) your hero give examples that people WILL understand. One more thing, the SR20DET upgrade kit that I conjoured up for a friend produced 298whp with a 60mm dp and 76mm.
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From: San Antonio, TX, 78240
Re: bigger cat or test pipe? (Dee)
i say run whatever size sewer pipe fits under ur car.....
i have a 92 hatchback w/ boost, only 5psi, but i have a custom 3" exhaust all the way from the lips of the turbo to the back of my bumper - no cat , and up until 3 days ago - no muffler, ...........i put a magnaflow 3" muffler on just to quiet down the highway drowning..........but its still fun to be sooooo loud when that wastegate cracks open!!!
i have a 92 hatchback w/ boost, only 5psi, but i have a custom 3" exhaust all the way from the lips of the turbo to the back of my bumper - no cat , and up until 3 days ago - no muffler, ...........i put a magnaflow 3" muffler on just to quiet down the highway drowning..........but its still fun to be sooooo loud when that wastegate cracks open!!!