# wastegate plumbed back into exhaust vs. atmosphere



## kcbmxer (Feb 22, 2002)

so what are the pros and cons to each.... my set up right now is plumbed back into the downpipe, but some have told me to just plumb it straight down and let it go to atmosphere. 
give me yoru opinions.


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## Monarchy (Sep 8, 2006)

*Re: wastegate plumbed back into exhaust vs. atmosphere (kcbmxer)*

Plumbing a separate tube (aka dump tube/screamer pipe) for the wastegate is the most efficient method (less pressure drop). Some people say that the plumbing is harder, but in my eyes it's a heck of a lot easier to just drop a striaght pipe from the wastgate then it is to weld the dump tube into your downpipe. 
Cons? It's loud. They aren't called screamers for nothing.


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## kcbmxer (Feb 22, 2002)

*Re: wastegate plumbed back into exhaust vs. atmosphere (Monarchy)*

so what is the benefit, of having less pressure drop? Are there noticable gains?


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## MKII16v (Oct 23, 1999)

*Re: wastegate plumbed back into exhaust vs. atmosphere (kcbmxer)*

The gains will vary depending on the engine,exhaust manifold, wastegate size and placement, turbine housing, and the exhaust system. Its way too loud on a street car and pretty much a ticket waiting to happen.


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## herbehop (May 4, 2004)

I used an open dump for ~ a year. I its quite loud and at first, I liked it. However, in the end (this week) I ended up having a new DP made for me by Sleepers Perfomance. It got annoying, I wanted to hear more turbo, less exhaust, and it attracted too much attention from the authorities








As for efficiency...Sure a dump is going to be more efficient, but I know people making ~500whp with a reroute so I'm not sure how much it matters... 
A pic of my new downpipe w/ reroute.


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## MKII16v (Oct 23, 1999)

*Re: (herbehop)*

FWIW Atp has an adapter flange that will let you rotate the wastegate 90 degrees to make pluming easier.
To the last poster....you setup looks great.


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## Ohio Brian (Aug 13, 2001)

*Re: (MKII16v)*

And with an open dump, when you hear the scream, you know you're at full boost.


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## 1.8TRabbit (Nov 15, 2004)

*Re: wastegate plumbed back into exhaust vs. atmosphere (kcbmxer)*

Pro for rerouting it back in. = better spool http://****************.com/smile/emthup.gif


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## 801pete (Apr 20, 2006)

*Re: wastegate plumbed back into exhaust vs. atmosphere (1.8TRabbit)*

who told you that nonsense?


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## 1.8TRabbit (Nov 15, 2004)

*Re: wastegate plumbed back into exhaust vs. atmosphere (801pete)*


_Quote, originally posted by *801pete* »_who told you that nonsense? 
 More back pressure into the exhaust = quicker spool. http://****************.com/smile/emthup.gif


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## 801pete (Apr 20, 2006)

oh wow you couldn't be more wrong. 
Turbocharger turbines work on the pressure drop across the turbo. High tempurature, high pressure gasses on one side, expend energy turning the turbine, and end up as low pressure, lower tempurature gasses on the other. 
If you increase the backpressure against the turbo, you decrease the pressure difference from one side to another, and the turbine can't extract as much energy. Sort of like a hydro electric plant out in the middle of a river, versus a hydro plant with lake mead on one side, and a river on the other. 
Furthermore, since the wastegate isn't open at all during spool up, really it makes NO difference at all to spool either way. I just felt like expanding upon the backpressure above because it is very important with regards to your downpipe and exhaust choices. 
So, lets clear this up... More pressure PRE turbo results in quicker spool. This is the premise for manifold / turbo wraps and coatings decreasing spool time... More pressure POST turbo = more lag. 
Wastegate in / out / upside down/ in the drivers lap / whatever... doesn't effect spoolup one bit, because the wastegate is closed and not operating at all during spool up. The ONLY critical thing which regards to the wastegate involving spoolup is that regardless of setup you must ensure that the gate is not leaking, and not opening prematurely.


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## Issam Abed (Feb 12, 2004)

*Re: wastegate plumbed back into exhaust vs. atmosphere (1.8TRabbit)*


_Quote, originally posted by *1.8TRabbit* »_ More back pressure into the exhaust = quicker spool. http://****************.com/smile/emthup.gif 

Peugeot 306 T16 with a 2.5" downpipe into a 2" exhaust (exhaust was not upgraded)
@ 21Psi - 213whp
@ 16Psi - 221whp
You do the math....


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## MKII16v (Oct 23, 1999)

*Re: wastegate plumbed back into exhaust vs. atmosphere (Wizard-of-OD)*

2" exhaust for mad spool gains yo








Just like how its pointless to run a big downpipe and exhaust when most turbine outlets are under 3"

















_Modified by MKII16v at 2:51 PM 9-13-2006_


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## 1.8TRabbit (Nov 15, 2004)

*Re: (801pete)*


_Quote, originally posted by *801pete* »_oh wow you couldn't be more wrong. 
Turbocharger turbines work on the pressure drop across the turbo. High tempurature, high pressure gasses on one side, expend energy turning the turbine, and end up as low pressure, lower tempurature gasses on the other. 
If you increase the backpressure against the turbo, you decrease the pressure difference from one side to another, and the turbine can't extract as much energy. Sort of like a hydro electric plant out in the middle of a river, versus a hydro plant with lake mead on one side, and a river on the other. 
Furthermore, since the wastegate isn't open at all during spool up, really it makes NO difference at all to spool either way. I just felt like expanding upon the backpressure above because it is very important with regards to your downpipe and exhaust choices. 
So, lets clear this up... More pressure PRE turbo results in quicker spool. This is the premise for manifold / turbo wraps and coatings decreasing spool time... More pressure POST turbo = more lag. 
Wastegate in / out / upside down/ in the drivers lap / whatever... doesn't effect spoolup one bit, because the wastegate is closed and not operating at all during spool up. The ONLY critical thing which regards to the wastegate involving spoolup is that regardless of setup you must ensure that the gate is not leaking, and not opening prematurely. 

WOW! I thought it did make a difference.








I guess I will eat my words and admit. I was wrong. I was mislead and believed it made a difference. Hmm... Learn something new everyday!


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## 1.8TRabbit (Nov 15, 2004)

*Re: (1.8TRabbit)*

And another question then. Why do people need back pressure then?


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## MKII16v (Oct 23, 1999)

*Re: (1.8TRabbit)*

Another misconception.


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## QuickK03Crap (Oct 5, 2004)

*Re: (MKII16v)*


_Quote, originally posted by *MKII16v* »_Another misconception.

In turbo motors anyways. lol


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## 801pete (Apr 20, 2006)

You'll have plenty (too much) backpressure AT the engine itself anyways because of the ristrictive turbine in the exhaust path... So, really any backpressure downstream of the turbo isn't adding any benefit.


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## GoKart_16v (Dec 17, 2004)

*Re: (1.8TRabbit)*


_Quote, originally posted by *1.8TRabbit* »_Why do people need back pressure then?









ask the women...especially those want it harder


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## GTijoejoe (Oct 6, 2001)

*Re: (1.8TRabbit)*


_Quote, originally posted by *1.8TRabbit* »_
WOW! I thought it did make a difference.








I guess I will eat my words and admit. I was wrong. I was mislead and believed it made a difference. Hmm... Learn something new everyday!
















you weren't totally wrong. There is a bit of truth, only if you have a digital boost controller which hides the boost from the WG until it meets the required level, will the wastegate open fully at an instant, other wise, a rerouted WG into a none sufficient DP size WILL effect spool up. Your wastegate starts to open pretty early until you reach max boost, at 10psi My wastegate was cracking at about 3 or so, that is just how it happens, the diagraph in the WG isn't going to know that you want XX amount of boost at XX time, unless you hide it. Only becasue you have a .6,.8, 1.0 etc. spring doesn't mean that your WG is going to open at that instantaneous boost level when it is reached (its not magic)
Now how much does it really effect spool up???? Probably not much if really at all if you have a proper sized DP, having a 2.25" dp and rerouting your dumptube... I garruntee you will have a slight laggier spool.
On the other hand... I ran and open dumptube for 2 years and personally, I got sick of how loud it really is. Driving WOT next to a large van, truck, close bulding etc. was almost ear piecing when the sound bounces back into your windows.
So I rerouted it with a 3" dp, and hearing the crazy spool of the turbo is more worth it.





_Modified by GTijoejoe at 3:37 PM 9-14-2006_


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## 1.8TRabbit (Nov 15, 2004)

*Re: (GTijoejoe)*


_Quote, originally posted by *GTijoejoe* »_
you weren't totally wrong. There is a bit of truth, only if you have a digital boost controller which hides the boost from the WG until it meets the required level, will the wastegate open fully at an instant, other wise, a rerouted WG into a none sufficient DP size WILL effect spool up. Your wastegate starts to open pretty early until you reach max boost, at 10psi My wastegate was cracking at about 3 or so, that is just how it happens, the diagraph in the WG isn't going to know that you want XX amount of boost at XX time, unless you hide it. Only becasue you have a .6,.8, 1.0 etc. spring doesn't mean that your WG is going to open at that instantaneous boost level when it is reached (its not magic)
Now how much does it really effect spool up???? Probably not much if really at all if you have a proper sized DP, having a 2.25" dp and rerouting your dumptube... I garruntee you will have a slight laggier spool.
On the other hand... I ran and open dumptube for 2 years and personally, I got sick of how loud it really is. Driving WOT next to a large van, truck, close bulding etc. was almost ear piecing when the sound bounces back into your windows.
So I rerouted it with a 3" dp, and hearing the crazy spool of the turbo is more worth it.




_Modified by GTijoejoe at 3:37 PM 9-14-2006_

God! I feel like a moron! For about two years I have been lead to believe that spool up is faster with rerouted dumo tube!







And more back pressure is better for a bigger turbo to help it spool faster.








I'd like to get my hands on the person that mislead me!


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## Rado.16vT (May 25, 2005)

*Re: wastegate plumbed back into exhaust vs. atmosphere (kcbmxer)*

let it out, sounds cool. if you let it inside the downpipe it will cause increase in backpressure giving you more lag depending on the size of your dp. Make sure if you go for open dump to route the gases properly not just blow them in the engine bay as you will suck that back into engine reducing your O2 content.


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## DrunkenMunkey (Jun 29, 2005)

*Re: wastegate plumbed back into exhaust vs. atmosphere (Rado.16vT)*

DUMP! For every reason. One unless you have a twin scroll turbo and the correct exhaust there are chances for exhaust turbulance (maybe turbine stall). It sounds ridiculous. Its loud but not that bad. Take your foot out of it. There is power there. Did I say it sounds DOPE. 
I often visit the Nurburgring and drive it, around the Wippleman I often get peeps jumping up and down from the sick sounds. I get comments from uber cars and they love the sound. Dump just do it the looks on faces when they are like ahhhh VW?
Abbot


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## phatvw (Aug 29, 2001)

*Re: wastegate plumbed back into exhaust vs. atmosphere (DrunkenMunkey)*

Why not have the best of both worlds: run a re-route and a test pipe for track days, put a muffler on for the street.


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## 92-8valver (Oct 9, 2003)

*Re: wastegate plumbed back into exhaust vs. atmosphere (phatvw)*

some porsches use a small muffler on the wg dump


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## 801pete (Apr 20, 2006)

*Re: (GTijoejoe)*


_Quote, originally posted by *GTijoejoe* »_
you weren't totally wrong. There is a bit of truth, only if you have a digital boost controller which hides the boost from the WG until it meets the required level, will the wastegate open fully at an instant, other wise, a rerouted WG into a none sufficient DP size WILL effect spool up. Your wastegate starts to open pretty early until you reach max boost, at 10psi My wastegate was cracking at about 3 or so, that is just how it happens, the diagraph in the WG isn't going to know that you want XX amount of boost at XX time, unless you hide it. Only becasue you have a .6,.8, 1.0 etc. spring doesn't mean that your WG is going to open at that instantaneous boost level when it is reached (its not magic)
Now how much does it really effect spool up???? Probably not much if really at all if you have a proper sized DP, having a 2.25" dp and rerouting your dumptube... I garruntee you will have a slight laggier spool.
On the other hand... I ran and open dumptube for 2 years and personally, I got sick of how loud it really is. Driving WOT next to a large van, truck, close bulding etc. was almost ear piecing when the sound bounces back into your windows.
So I rerouted it with a 3" dp, and hearing the crazy spool of the turbo is more worth it.




_Modified by GTijoejoe at 3:37 PM 9-14-2006_


Spring only suxx! 


_Modified by 801pete at 7:23 PM 9-14-2006_


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