Manifold mounted WG vs O2 mounted WG on a 60-1

[hardware]

I ran a search and didn't find out any advantages either way. Maybe it's just me, but it seems like mounting a WG on the O2 housing doesn't really allow it to do what it's supposed to, which is bypass exhaust gasses around the turbine. I dunno, thats why I'm asking. I'm thinking about getting an RS60T so let me know what ya'll think. Thanks!

 

[91gvr4]

On my RS60T I have a manifold mounted wastegate. I like it, it worked perfect on my 20g too.

 

[rowlex]

sorry this is just on a evoIII big16 setup but it works GREAT!

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[oldman]

The biggest cause of boost creep is the lack of accessibility to the wastegate path in the turbine inlet, the efficiency of an o2 mounted external wastegate is still limited to that restriction. Without properly porting the turbine inlet, an o2 mounted wastegate will not be a guarantee fix. Manifold mounted like rowlex's setup would be a better choice.

 

[1fastlaser]

ive been running a manifold mounted wastegate for 3 1/2 years now,i went to one because i dont like internals because they creep,mainly because my big16g started to creep,and i knew i was going bigger...now im on a 60-1 p trim and its great,perfect control,no creeping...i would go with a 38mm tial or bigger,i think my 35mm is just on the small side,and im gonna be going bigger soon enough

 

[Burnett03]

Maybe it's just me, but it seems like mounting a WG on the O2 housing doesn't really allow it to do what it's supposed to, which is bypass exhaust gasses around the turbine. I dunno, thats why I'm asking. !

why not? Its exactly like an internal gate.. It blocks exhaust from coming out of the wastegate, thus making it go back and spin the turbine.

 

[hardware]

It blocks exhaust from coming out of the wastegate, thus making it go back and spin the turbine.

That's exactly what I don't want it to do. I'm trying to avoid creep at lower boost levels, due to the fact that this is my only mode of transportation. Forgive me if I'm such a noob at this, but this is just my train of thought about the exhaust gasses. We all know that exhaust gas is fluid, so lets imagine a leaky hose spinning our turbine instead of the exhaust.

Manifold Mount - Leak is before the turbine, allowing a portion to completely bypass, and not give the energy to spin the turbine in the first place(best option IMO)

Internal - Depending upon the design of the housing, it could be before or after, in my case, the AGP RS60T, I believe its right where the housing starts to curve downward toward the turbine outlet, closer to the manifold than the O2, but still too small to be effective

O2 Mount - Leak is after the turbine. All exhaust gasses have to pass through the turbine housing to allow backpressure to be relieved on the exhaust side.

What I'm thinking about the O2 mounted setups is, all they do is relieve backpressure on the system, not really solving the problem of creep unless you have a much larger wastegate than you need. Look at FP's v-band mounted system on the turbine housing of their 30-series turbos. It uses a 44mm wastegate mounted far upstream of the turbine wheel. Obviously somebody smarter than me designed the thing, but could a 40mm do the same job mounted in the collector?

So now that I've gone cross-eyed trying to sound smart..... WTF

 

[oldman]

Internal - Depending upon the design of the housing, it could be before or after, in my case, the AGP RS60T, I believe its right where the housing starts to curve downward toward the turbine outlet, closer to the manifold than the O2, but still too small to be effective

What is the point of a wastegate after turbine? Can you give us one example? The sole purpose of a wastegate is to diver gas before it enters the turbine.

What I'm thinking about the O2 mounted setups is, all they do is relieve backpressure on the system, not really solving the problem of creep unless you have a much larger wastegate than you need.

Again, an o2 mounted external wastegate is before the turbine wheels, not after. Not quite sure what you mean by back pressure.

 

[hardware]

This would work a lot better with pictures.....

You're right, thats why I was asking why go with an o2 mounted wastegate. I don't understand how one is upstream of the turbine wheel. That is exactly what I was looking for clarification on. If you could please explain it to me, I'd really appreciate it.

 

[rowlex]

this is a picture of an evoIII 16g turbo, the lower hole is the exhaust wheel the upper smaller hole is the internal wastegate passage (SAME place an o2 mounted external wastegate would relieve pressure from. all that would be done is the "flapper" (also could be considered a door) would be taken off and the hole would be ported larger. It does in fact divert exhaust gases around the turbine, it's just *right* before it.

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Here is a picture with the flapper door open this diverts the gas around the turbine

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here's a picture of a turbo INLET the hole in the middle/right side is the path the exhaust would follow toward the exhaust wheel

the hole on the left side is the wastegate hole, it will divert the exhaust around the turbine wheel, because it is placed before the turbine in the exhaust path.

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So as long as the o2 mounted wastegate is large enought, as well as the hole that the exhaust needs to fit through it will stop creep just fine.

 

[oldman]

The wastegate, though a part of the turbine housing, is located at the inlet before the turbine wheels. The wastegate/flapper opens when the desired boost level is reached diverting part of the exhaust gas through the wastegate path reducing the amount of air passing through the turbine wheels preventing it from spinning out of control.

Boost creep is caused by faulty/poor design of the wastegate path causing it not able to efficiently divert enough air therefore the boost level continues to rise (boost creep) after the flapper opens.

There are two effective ways to deal with boost creep. 1. External mounted on manifold and weld the flapper shut. 2. Properly port the turbine housing to fix the poorly designed wastegate path.

Back to your original question. An o2 mounted external wastegate is mounted after the wastegate path therefore a proper port job is still required. Here's an on going thread about porting and boost creep with great pictures that will help you understand more.

 

[hardware]

Thanks for the info.

 

[oldman]

Thanks for the info.

You're welcome. I think the problem is that you have never seen a turbo when it's out of a car. Once you have a turbo on one hand and an o2 housing in the other, things will become clear. Good luck.