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AHB900
10-26-2006, 05:40 PM
Hey guys i was wondering what kind of gains would i see with a GHL highflow cat.. a upgraded downpipe... and a 2.5 inch custom resonated exhaust system? im currently chiped got the forge 007 dv and evoms intake.. would i see a noticible gain? is it worth it? I cant get a test pipe cause of emissions here so i think the next best thing is a highflow cat by ghl its 350 bucks...


Thanks

lilr4o8
10-27-2006, 03:43 AM
well when do you have to smog, is it anytime soon?
if its in 2 years then go for the test pipe wait you're stock ehh its up to you

iowaboostin
10-27-2006, 05:03 AM
Freeing up backpressure on a turbo'd car will obviously yield some gains.. I'm not so sure you'll FEEL any difference but it'll be roughly a 5-10hp gain I would guess.

mike-2ptzero
10-27-2006, 07:32 AM
A good flowing exhaust will move the power band up a little bit in the rpm's and give you a slight gain in peak hp. If you are running a stock turbo expect some decrease in tq since reducing back pressure on our cars causes a loss in flow restriction thru the internal wg causing the turbo to spool up a little later.

AHB900
10-27-2006, 11:42 PM
oh waaaa i dont wanna get slower spool up lol... hmm im debating but like is it worth geting a down pipe? thats the one im debating on i think i might just keep my stock cat iono...

onemoremile
10-27-2006, 11:47 PM
the labree cat from tantrumwerks is a hundred bucks cheaper than that one you listed.

BoostFrenzy
10-27-2006, 11:57 PM
Originally posted by mike-2ptzero
A good flowing exhaust will move the power band up a little bit in the rpm's and give you a slight gain in peak hp. If you are running a stock turbo expect some decrease in tq since reducing back pressure on our cars causes a loss in flow restriction thru the internal wg causing the turbo to spool up a little later.

In a turbocharged engine *THE EXHAUST HOUSING ON THE TURBO* is the bottleneck with regard to engine backpressure, you're not going to see anything but gains ACROSSED THE BOARD FROM LOWEND TORQUE TO TOPEND even if you had no cat/downpipe at all.

And to further compound that, the ability to reduce the boost threshold with less backpressure post-turbo is going to significantly increase bottom end torque due to the ability to hit the threshold sooner.

Cats and exhaust choices on a turbo car are as simple as do you want to hug trees and how loud is too loud, how big is too big...

AHB900
10-28-2006, 12:07 AM
Originally posted by onemoremile
the labree cat from tantrumwerks is a hundred bucks cheaper than that one you listed.

does that work on the FWD if it does can u show me the link

thanks

mike-2ptzero
10-28-2006, 08:30 AM
Originally posted by BoostFrenzy
In a turbocharged engine *THE EXHAUST HOUSING ON THE TURBO* is the bottleneck with regard to engine backpressure, you're not going to see anything but gains ACROSSED THE BOARD FROM LOWEND TORQUE TO TOPEND even if you had no cat/downpipe at all.

And to further compound that, the ability to reduce the boost threshold with less backpressure post-turbo is going to significantly increase bottom end torque due to the ability to hit the threshold sooner.

Cats and exhaust choices on a turbo car are as simple as do you want to hug trees and how loud is too loud, how big is too big...


I am suprised you dont know this since you do own an A4.


Since the internal wastegate is before the exhaust wheel, when you reduce the back pressure just behind the back of the turbo the exhaust flow will take the path with the least amount of resistance. This is why most people have seen a decrease in tq when they decrease the back pressure between the back of the turbo and the down pipe by removing the cat. Just have to understand the wastegate is being controlled by a N75 valve that just does what it is told by the ecu which has NO clue as to what you have done to the back pressure.

I know this because of 6+ years experiance with the A4 1.8t and seeing that I have made the most power with the stock K03 turbo on a A4.

Also a well known shop that used to road race the A4 with the stock K03 at the time did some testing by pulling the cat and down pipe and the results were a pretty size decrease in bottom end tq.

bOOOOstedAudi
10-28-2006, 08:35 AM
better top end

ActiveMonkey
10-28-2006, 10:22 AM
After i got my exahust i noticed is was just barely a little slower off the line, but better once you get up in the RPM's.

AHB900
10-28-2006, 02:32 PM
hmm sounds interesting... by ne chance would this slower of the line thing make it much easier to stall? because my cousin is a machanic and his family like they have a shop that concentrates on more of audis and jags.. he told me removing the resonator will make it much easier for me to stall so he told me to forget bout it.

sean1.8t
10-28-2006, 06:13 PM
i don't know. when i put my testpipe on i notice better bottem end tq. maybe it is just in my head or i am just not getting what you guys are talking about

BoostFrenzy
10-28-2006, 08:47 PM
Originally posted by mike-2ptzero
I am suprised you dont know this since you do own an A4.


Since the internal wastegate is before the exhaust wheel, when you reduce the back pressure just behind the back of the turbo the exhaust flow will take the path with the least amount of resistance. This is why most people have seen a decrease in tq when they decrease the back pressure between the back of the turbo and the down pipe by removing the cat. Just have to understand the wastegate is being controlled by a N75 valve that just does what it is told by the ecu which has NO clue as to what you have done to the back pressure.

I know this because of 6+ years experiance with the A4 1.8t and seeing that I have made the most power with the stock K03 turbo on a A4.

Also a well known shop that used to road race the A4 with the stock K03 at the time did some testing by pulling the cat and down pipe and the results were a pretty size decrease in bottom end tq.

Well I don't think you're too bright so once I find a way to burn my own chips i'll slap the wideband in and beat your "records", all turbo cars have an electronic wastegate controller / boost controller, has NOTHING to do with the placement of the exhaust wheel, it vents the air back to the intake anyway... man reading most of your posts are a good laugh

BoostFrenzy
10-28-2006, 08:53 PM
Originally posted by mike-2ptzero
I am suprised you dont know this since you do own an A4.


Since the internal wastegate is before the exhaust wheel, when you reduce the back pressure just behind the back of the turbo the exhaust flow will take the path with the least amount of resistance. This is why most people have seen a decrease in tq when they decrease the back pressure between the back of the turbo and the down pipe by removing the cat. Just have to understand the wastegate is being controlled by a N75 valve that just does what it is told by the ecu which has NO clue as to what you have done to the back pressure.

I know this because of 6+ years experiance with the A4 1.8t and seeing that I have made the most power with the stock K03 turbo on a A4.

Also a well known shop that used to road race the A4 with the stock K03 at the time did some testing by pulling the cat and down pipe and the results were a pretty size decrease in bottom end tq.

Well I don't think you're too bright so once I find a way to burn my own chips i'll slap the wideband in and beat your "records", all turbo cars have an electronic wastegate controller / boost controller, has NOTHING to do with the placement of the exhaust wheel, it vents the air back to the intake anyway... man reading most of your posts are a good laugh

there's some good pics of a K03 on ebay, ALL EXHAUST EXITS THE REAR OF THE TURBO... the only thing the N75 does is bleed off pressure from the compressor so the mechanical wastegate diagram doesn't see it (spring pressure is always lower than desired pressure).

http://cgi.ebay.com/ebaymotors/Audi-A4-A6-VW-Passat-KKK-KO3-K03-Turbo-Charger-1-8T-K3_W0QQcmdZViewItemQQcategoryZ33742QQihZ014QQitemZ 330043022640QQrdZ1QQsspagenameZWDVW

onemoremile
10-28-2006, 10:32 PM
Whoa there hard charger. Play nice.

I think Mike is saying that the dinky little turbo is such a bottleneck that lowering the pressure downstream isn't going to give much of a net gain. The stock turbo and exhaust are well matched. Real backpressure gains get bigger as the turbos get bigger.

The Subey really benefits from exhaust work since there is so much room for improvement. Even then a simple cat back doesn't yield much on a WRX. The bottleneck in that system is before the turbo. Once that bottleneck is dealt with the HFC and cat back become cost efficient performance options. That teeny K03 acts pretty much the same way. Get a turbo with a bigger compressor housing and wastegate and you'll actually need a larger exhaust.

mike-2ptzero
10-28-2006, 10:59 PM
Originally posted by BoostFrenzy
Well I don't think you're too bright so once I find a way to burn my own chips i'll slap the wideband in and beat your "records", all turbo cars have an electronic wastegate controller / boost controller, has NOTHING to do with the placement of the exhaust wheel, it vents the air back to the intake anyway... man reading most of your posts are a good laugh

there's some good pics of a K03 on ebay, ALL EXHAUST EXITS THE REAR OF THE TURBO... the only thing the N75 does is bleed off pressure from the compressor so the mechanical wastegate diagram doesn't see it (spring pressure is always lower than desired pressure).

http://cgi.ebay.com/ebaymotors/Audi-A4-A6-VW-Passat-KKK-KO3-K03-Turbo-Charger-1-8T-K3_W0QQcmdZViewItemQQcategoryZ33742QQihZ014QQitemZ 330043022640QQrdZ1QQsspagenameZWDVW

WTF are you talking about? since this has nothing to do with what I even posted about. I dont see how you are going to "learn" to burn chips if you dont even know how to read. How did you go from talking about back pressure to now talking about what the hell the boost controller does with the air? What does that have to do with anything I was even remotely talking about? Maybe it is time you put down the pipe and step back from the keyboard since you seem to have posted your reply twice.

LOL you need a wide band to beat my records? Maybe you should go back to driving school too.

I find it funny how you "think" you know so much about the A4 but yet yours is fully stock. Maybe it is time you stop being a "keyboard" tuner and actually get some experiance first.

BoostFrenzy
10-29-2006, 12:33 AM
Originally posted by mike-2ptzero
WTF are you talking about? since this has nothing to do with what I even posted about. I dont see how you are going to "learn" to burn chips if you dont even know how to read. How did you go from talking about back pressure to now talking about what the hell the boost controller does with the air? What does that have to do with anything I was even remotely talking about? Maybe it is time you put down the pipe and step back from the keyboard since you seem to have posted your reply twice.

LOL you need a wide band to beat my records? Maybe you should go back to driving school too.

I find it funny how you "think" you know so much about the A4 but yet yours is fully stock. Maybe it is time you stop being a "keyboard" tuner and actually get some experiance first.

No, you had mentioned something about the N75 valve and boost regulation having in some part, anything to do with the torque gains or losses involved with a catless downpipe... which just isn't true, you will never lose an ounce of power removing cats/uncorking the exhaust on a turbo car, ever.

...and the state of my car being stock holds no bearing on my skills or abilities, unlike you i have an A4 for a winter beater and have absolutely no desire to throw money at it to still be disappointing, it's a city commuter, not a race car

here's what you said originally:


Originally posted by mike-2ptzero
I am suprised you dont know this since you do own an A4.


Since the internal wastegate is before the exhaust wheel, when you reduce the back pressure just behind the back of the turbo the exhaust flow will take the path with the least amount of resistance. This is why most people have seen a decrease in tq when they decrease the back pressure between the back of the turbo and the down pipe by removing the cat. Just have to understand the wastegate is being controlled by a N75 valve that just does what it is told by the ecu which has NO clue as to what you have done to the back pressure.

I know this because of 6+ years experiance with the A4 1.8t and seeing that I have made the most power with the stock K03 turbo on a A4.

Also a well known shop that used to road race the A4 with the stock K03 at the time did some testing by pulling the cat and down pipe and the results were a pretty size decrease in bottom end tq.

you = dumb.

AHB900
10-29-2006, 01:57 AM
hmm apparently my thread turned into a war...

k0mpresd
10-29-2006, 01:03 AM
Originally posted by BoostFrenzy
man reading most of your posts are a good laugh
[cool] [;)]

mike-2ptzero
10-29-2006, 07:15 AM
Originally posted by BoostFrenzy
No, you had mentioned something about the N75 valve and boost regulation having in some part, anything to do with the torque gains or losses involved with a catless downpipe... which just isn't true, you will never lose an ounce of power removing cats/uncorking the exhaust on a turbo car, ever.

...and the state of my car being stock holds no bearing on my skills or abilities, unlike you i have an A4 for a winter beater and have absolutely no desire to throw money at it to still be disappointing, it's a city commuter, not a race car

here's what you said originally:



you = dumb.


Well if I am dumb you must not have a brain.

It seems you have no clue about the basic functions of the ECU and N75 valve. If you allow more air to flow thru the wg which causes the boost made to decrease, the ECU doesn't tell the N75 to close more to increase the boost again. This is because the ECU has no clue there is less boost and the signal to the N75 is a set value in the ECU based on throttle position and rpm. The ecu cracks the wg open well before the exact boost level is made, so if more exhaust flow goes thru the wg the ecu has no way of closing the WG more to decrease that flow thru the WG to increase the boost level. The ECU has no way of reading boost pressure after the turbo to make adjustments so it can close the N75.(added) the map sensor on the dbw car is only used by the ecu as a safety feature not to help adjust the signal to the N75 valve. This is why the ecu throws a dtc when the boost levels are lower or higher then what the ecu is requesting.

Example

S4 owner ports out his WG outlets, by doing so he causes a less restriction within that outlet. This causes the boost to come on later( a lag) since less exhaust is going thru the turbo and the ECU has no way to close the N75 to increase spool up.

This is the same thing that happens when you decrease the back pressure right at the back of the turbo since the exhaust wheel is a restriction already. This then decreases the flow restriciton thru the wg outlet.

ECU/N75/WG 101 class dismissed.[;)]

bellofello
10-29-2006, 07:23 AM
I vote mike=wins, just because his a4 is, what 500 sumthin whp? I think he knows what he's talking about.

k0mpresd
10-29-2006, 08:00 AM
Originally posted by mike-2ptzero
This is because the ECU has no clue there is less boost and the signal to the N75 is a set value in the ECU based on throttle position and rpm....The ECU has no way of reading boost pressure after the turbo to make adjustments so it can close the N75.(added) the map sensor on the dbw car is only used by the ecu as a safety feature not to help adjust the signal to the N75 valve.
this is so far off its not even funny

you really are racking up some good posts lately [;)]

AudiRacerS4
10-29-2006, 08:12 AM
to get back on topic i felt a pretty good gain after i installed my testpipe [:p]

BoostFrenzy
10-29-2006, 01:34 PM
Originally posted by mike-2ptzero
Well if I am dumb you must not have a brain.

It seems you have no clue about the basic functions of the ECU and N75 valve. If you allow more air to flow thru the wg which causes the boost made to decrease, the ECU doesn't tell the N75 to close more to increase the boost again. This is because the ECU has no clue there is less boost and the signal to the N75 is a set value in the ECU based on throttle position and rpm. The ecu cracks the wg open well before the exact boost level is made, so if more exhaust flow goes thru the wg the ecu has no way of closing the WG more to decrease that flow thru the WG to increase the boost level. The ECU has no way of reading boost pressure after the turbo to make adjustments so it can close the N75.(added) the map sensor on the dbw car is only used by the ecu as a safety feature not to help adjust the signal to the N75 valve. This is why the ecu throws a dtc when the boost levels are lower or higher then what the ecu is requesting.

Example

S4 owner ports out his WG outlets, by doing so he causes a less restriction within that outlet. This causes the boost to come on later( a lag) since less exhaust is going thru the turbo and the ECU has no way to close the N75 to increase spool up.

This is the same thing that happens when you decrease the back pressure right at the back of the turbo since the exhaust wheel is a restriction already. This then decreases the flow restriciton thru the wg outlet.

ECU/N75/WG 101 class dismissed.[;)]

Porting the wastegate outlet on any housing is going to have negative results with regard to factory boost control (and makes a mbc or other form of boost control neccesary), however removing restriction behind the turbo and not touching the wg flapper/outlet port is NOT.

Even if it does, you go get a mbc and dial it in, either way you will never, ever, ever never, ever lose power going to a catless setup

sorry everyone around here thinks you know what you're talking about because you make good power with a 1.8t, but money spent doesn't equate to intelligence

CaSp3r9
10-29-2006, 01:55 PM
http://plig.org/things/pictures/tn/arguing.med.jpg

Not saying I'm any more knowledgable about cars than either of you because I'm definitely not. But honestly, why does every thread on here have to turn into an ever lasting battle between people over something that really doesn't matter? Everyone has their own opinions from their own personal experiences or lack thereof. Horray?

Wizard-of-OD
10-29-2006, 02:04 PM
Originally posted by CaSp3r9 Everyone has their own opinions from their own personal experiences or lack thereof. Horray? [/B]
Not to sound like a total moron but horsepower wins an argument.
Mike is @ what now? 500AWhp?I dont know about you but Id take whatever he types with the confidence that he must know what the hell he is talking about.
Best advice I can give is to shut up and read....

BoostFrenzy
10-29-2006, 02:24 PM
Originally posted by Wizard-of-OD
Not to sound like a total moron but horsepower wins an argument.
Mike is @ what now? 500AWhp?I dont know about you but Id take whatever he types with the confidence that he must know what the hell he is talking about.
Best advice I can give is to shut up and read....

LOL that's just because you don't know any better either, this forum is great

k0mpresd
10-29-2006, 03:12 PM
issam (wizard) knows his ish...i wouldnt speak bad about him

mike has a lot of knowledge but is not *always* right..he just thinks he is

and i think mike and issam know each other...looks like we have a little friendly bandwagoning going on [;)]

mike-2ptzero
10-29-2006, 04:41 PM
Originally posted by BoostFrenzy
Porting the wastegate outlet on any housing is going to have negative results with regard to factory boost control (and makes a mbc or other form of boost control neccesary), however removing restriction behind the turbo and not touching the wg flapper/outlet port is NOT.

Even if it does, you go get a mbc and dial it in, either way you will never, ever, ever never, ever lose power going to a catless setup

sorry everyone around here thinks you know what you're talking about because you make good power with a 1.8t, but money spent doesn't equate to intelligence


Who said anything about losing power when reducing back pressure, I said the K03 will lose some low end tq but will have some gains in the mid-high rpm range.

sorry to tell you but I have always worked directly with the shops when it came to my car and worked directly with GIAC when it came to tuning back when I had my K03 and PES T28 setup. I know why you think I just send my car to shops and just pick it back up with out every dealing with my car at all. But what should I expect from a Audi noob.

sean1.8t
10-29-2006, 06:52 PM
Originally posted by CaSp3r9
Not saying I'm any more knowledgable about cars than either of you because I'm definitely not. But honestly, why does every thread on here have to turn into an ever lasting battle between people over something that really doesn't matter? Everyone has their own opinions from their own personal experiences or lack thereof. Horray?


i second that.

and why does it always seem that Boostfrenzy (mr stock a4 cause i hate a4's yet i still get on here like im an audi enthusiest guy) is in the mix?

BoostFrenzy
10-29-2006, 07:33 PM
Originally posted by sean1.8t
i second that.

and why does it always seem that Boostfrenzy (mr stock a4 cause i hate a4's yet i still get on here like im an audi enthusiest guy) is in the mix?

nah i love a4's for their intended purpose, but i choose to keep mine stock and drive it through the snow, doesn't mean i won't exploit morons in the process

TQMB5
10-29-2006, 08:13 PM
not trying to get involved cause shit i could really ccare less but just wondering why you dont through some snow tires on the sti? its awd. my buddies is a haus in the snow and its fun to drive[:p]

BoostFrenzy
10-29-2006, 08:30 PM
Originally posted by TQMB5
not trying to get involved cause shit i could really ccare less but just wondering why you dont through some snow tires on the sti? its awd. my buddies is a haus in the snow and its fun to drive[:p]

because I got the A4 dirt cheap, about this time last year I promised to sell all my cars (02 wrx, 94 rx7 tt, 90 audi 90q, 93 escort at the time) and buy a STi, keeping it the primary/all seasons vehicle... but i broke this promise this year because I want to sell it for a Z06 and the audi came my way for 4k so i was like hrmm

Wizard-of-OD
10-29-2006, 08:48 PM
Originally posted by BoostFrenzy
LOL that's just because you don't know any better either, this forum is great
I know what I need to know[;)]

k0mpresd
10-29-2006, 08:56 PM
i tihnk you flip from forum to forum as fast as i do

reply here then another reply on vortex 4 mins later [cool]

Wizard-of-OD
10-29-2006, 09:02 PM
Originally posted by k0mpresd
i tihnk you flip from forum to forum as fast as i do

reply here then another reply on vortex 4 mins later [cool]
It helps when you have 8 forum windows open[;)]
I am everywhere.... [:D]