Exhaust Size!?

[dragon2144]

I have a 2g Talon FWD Tsi and im looking at going with a EVOIII 16g in the future. I'm going with a stainless VRS exhaust. My problem is what size to go with 2.5 inch or 3 inch? Im looking at going with about 400hp not much more then that. Yes im going to have a cat on it so factor that in. Also how much hp about is about max on a 2.5 exhaust. I know there is a lot of factors but if any one has a EVOIII 16g and a 2.5 vs. 3 inch exhaust numbers would be nice. thanks every one that helps me.

 

[JusMX141]

If you're serious about making 400hp, then 3".

If you're serious about not getting boost creep trying to run less than 20psi, then 2.5".

 

[Joshuah Stedman]

I have a 2g Talon FWD Tsi and im looking at going with a EVOIII 16g in the future. I'm going with a stainless VRS exhaust. My problem is what size to go with 2.5 inch or 3 inch? Im looking at going with about 400hp not much more then that. Yes im going to have a cat on it so factor that in. Also how much hp about is about max on a 2.5 exhaust. I know there is a lot of factors but if any one has a EVOIII 16g and a 2.5 vs. 3 inch exhaust numbers would be nice. thanks every one that helps me.

I went 3', and im glad i went 3 inch. Go with the 3 or youll regret it later...

 

[dragon2144]

If you're serious about making 400hp, then 3".

If you're serious about not getting boost creep trying to run less than 20psi, then 2.5".

My goal is to make 400hp by keeping the EVOIII 16g under 20 psi for reliability and longer life for the turbo so i don't have to rebuild it every year. im looking at a stoker kit or high compression pistons. something like 9.0:1 or high if i can do it. So im looking at high compression with low boost is what im going for. will the 2.5" be ok for that or will it be better to go 3"?

p.s. Boost creep is where it shots up and then slowly comes down at high rpm?

 

[Doubleot]

I've got 3"
Never looked back

 

[deerhunter0881]

go 3"

 

[JusMX141]

You're not going to make it to 400 horses under 20psi too easily on a 16G. There's just not enough airflow available at that boost level to get you to your goal. Perhaps with 10.5:1 pistons and 200-octane gasoline such a task could be accomplished; higher compression or aggressive timing will all help, but it's going to boil down to more boost being required.

Don't be scared to crank up the boost. Evo III 16G's are one of the most reliable turbos out there....they use the same center housing and internals as a standard 20G, and even the FP Green and FP Red models. Obviously these turbos are designed for use with boost levels much higher than 20psi.

Boost creep is where the boost is uncontrollable because your exhaust system is too big and too unrestricted to allow the Evo III 16G's wastegate system to function properly. Wastegate mods and longer-throw actuators sometimes help, but it all boils down too a case of too little exhaust restriction.

 

[USER_22]

3" all the way, it should provide you with more then enough to handle your goals.

 

[dragon2144]

Thanks to all of you will be going with 3" and wont look back

 

[boosteclipse]

3" all the way!

 

[spawn87]

just port the hell out of that turbo get a good o2 housing to match and go 3inch all the way especially if your gana have a hi-flow cat. i did and i have no creep problems and leaves room for more power

 

[vettesmoker]

im pretty sure boost creep is from too restrictive of wastegate passage, causing more exhuast gasses to go through the turbine as if the wastegate was closing. 3" pipe wont cause that. dont want to run big boost? port the wastegate passage.

 

[gstryyder]

The only person that mentioned any note worthy info for you is jusmx141... For what you are looking to do... I say good luck with 400whp on your 16g. Especially with how your going about doing it... As for your exhaust, you should run a 2.5" DP, 3" catback. Anything bigger will only hurt you. I know girls will not agree... but bigger isn't always better. It's about knowing how to maximize the effectiveness of what you have to work with. Rather then trying to makeshift fix a problem.... start out right. There is a science that goes into this stuff. It's like having too big of an intercooler piping or core... Doesn't help performance just because you have 3" piping and a 4" thick core on a 14b... C What I'm sayin'?

 

[bluevoviii]

Also, if you are thinking about building your car in the future, it will be nice to already have an exhaust that can handle it on your car already... 3inches

 

[JLindback]

Dont want to go 2.5inch then later regret not getting the 3in. Then you will have a used 2.5 inch and have to get a new 3in. Double the money spent in the long run.

 

[JusMX141]

Thanks to all of you will be going with 3" and wont look back

Looks like all the posts made beyond #9 are a waste of server bandwidth.


The bottom line:

- To anyone looking for a good exhaust system for their daily driver under 18-20psi, try full 2.5" or use a 3" cat-back with the stock downpipe. If you add too much exhaust flow to certain turbochargers (especially the Evo III 16G), you will suffer from boost creep that will make you pull your hair out.

- To anyone looking for a great low-restriction system for their 20psi+ or high lb/min turbo, full 3" is the answer.

 

[ziggo0]

What about 20psi on the dot?

 

[JusMX141]

At some point, the level of boost creep negates the maximum boost level you're running. It seems like once you start creeping at 12psi, it just keeps climbing and climbing most of the time beyond the capability of your fuel system because the exhaust flows too freely and never allows any type of turbine restriction. At 20psi, there is already enough turbine housing backpressure due to the added boost level to allow the wastegate system to function properly under most circumstances....and even if it does creep, it's not going to creep too far.

If you're sitting at 20psi, just go for the 3". Boost is very addictive- if you're at 20psi, in less than a year you'll be a 22-23psi. The following year you'll be putting in head studs so you can run 25psi, and so on. At that point you'll appreciate the 3" system.

I'm basically speaking for the 12psi guys that bolt a 3" system on their car and wonder why they have absoultely no control of boost.

 

[dragon2144]

At some point, the level of boost creep negates the maximum boost level you're running. It seems like once you start creeping at 12psi, it just keeps climbing and climbing most of the time beyond the capability of your fuel system because the exhaust flows too freely and never allows any type of turbine restriction. At 20psi, there is already enough turbine housing backpressure due to the added boost level to allow the wastegate system to function properly under most circumstances....and even if it does creep, it's not going to creep too far.

If you're sitting at 20psi, just go for the 3". Boost is very addictive- if you're at 20psi, in less than a year you'll be a 22-23psi. The following year you'll be putting in head studs so you can run 25psi, and so on. At that point you'll appreciate the 3" system.

I'm basically speaking for the 12psi guys that bolt a 3" system on their car and wonder why they have absoultely no control of boost.

I have head studs and cometic Head Gasket from when i built my head after the time belt broke Yea I'm going with 3" thank everyone for there help.

 

[92dsm1]

Not to jack your thread, but I have 2.5" DP to 3" catback with a ported 14B and I have terrible boost creep with my MBC all the way out 20 psi minimum. I am also planning on going with a bigger turbo later, the reason for the 3" cat back. If I need more flow I will only have to change my DP.