O2 housing questions

[vtown661]

Ok ive been researching O2 housing on this site for a while and I just cant seem to understand some things. In what order do the exhaust components go on a turbo car? I thought it was exhaust mani - turbo - O2 housing - downpipe - cat- catback exhaust. If thats correct then how does an O2 mounted wastegate work since the WG has to be before the turbo? Also I have heard about people deleting their O2 housing. When would this be appropriate? Is this only for drag cars or is it an option for a daily driver? Also, Is it true that in order to recirculate a manifold mounted wategate you must have piping from the wastegate to the O2 housing or downpipe? and can T3 turbos have a recirculated O2 housing? Sorry for the dumb questions but its a lot harder to learn when you cant actually see what youre talking about.

 

[wont_luz]

Some delete their o2 housing if they have an external wastegate, such as a deltagate. The wastegate is hooked up to the exhaust manifold, and the opposite end is sometimes dumped into the exhaust downpipe, or sometimes extended down a ways and dumped to the atmosphere (which sounds awesome I think).

 

[synthetek]

how does an O2 mounted wastegate work since the wg has to be before the turbo?

The wg dose not have to be before the turbo it can be mounted on the manifold before the turbo, but on an internally gated turbo the wg is on the exhaust side of the turbo. The wg flapper can be removed on an internally gated turbo and a wg can be mounted on the o2 housing instead.

I have heard about people deleting their O2 housing. When would this be appropriate? Is this only for drag cars or is it an option for a daily driver?

Some turbos with no internal wg just need a DP

Is it true that in order to recirculate a manifold mounted wg you must have piping from the wg to the O2 housing or downpipe?

If you don't want the wg to dump to atmosphere the dump tube from the wg has to be routed back into the downpipe.

 

[1gDSM4g63]

High boost big turbos require external wastegates.

I wouldn't say exhaust manifold's that mount external wastegates are better. There are o2 housing, recirculating o2 housing, or dump pipe for external wastegate too.

 

[kenamond]

Ok ive been researching O2 housing on this site for a while and I just cant seem to understand some things. In what order do the exhaust components go on a turbo car? I thought it was exhaust mani - turbo - O2 housing - downpipe - cat- catback exhaust.

That's correct. You can combine various components past the turbo (like if you remove the cat, it's just one long exhaust pipe from the DP to the muffler).

If thats correct then how does an O2 mounted wastegate work since the WG has to be before the turbo?

The turbine housing contains both the inlet and outlet for the turbine. Exhaust can go into the housing from the ex. mani., through the turbine wheel, out the turbine outlet, and into the O2 housing. Or it can go into the housing from the ex. mani., through the wastegate passage (before the turbine wheel), and into the O2 housing. The WG just bypasses some of the exhaust gas around (adjusting how much goes through one or the other is how boost is controlled).

Basically, there is a hole in the side of the tubine inlet with a valve of some sort covering it. When the valve opens, exhaust can leak past. Since it's not going through the turbine wheel, it's not contributing energy (torque) to the shaft that drives the compressor wheel.

Here is a picture of the turbine housing of a FPB28 (left) and blown T25 (right). The O2 housing bolts to that flat surface (with 4 bolts). The manifold bolts to the bottom flange, so exhaust would be going up into the housing in that picture. Notice that the lower right side of the housing has a bell-shaped passage cast into it with a "flapper" valve in it. You can also see the lever on the outside of the housing that opens/closes that flapper valve. The lever and flapper are connected via a shaft running through the wall of the housing. Also notice that the flapper is in between the exhaust manifold and turbine wheel.

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The O2 housing has two pipes (one for the wastegate flow and one for the turbine exit flow) that merge together. The downpipe bolts to the O2 housing after flow is collected to one O2 outlet pipe.

Also I have heard about people deleting their O2 housing. When would this be appropriate? Is this only for drag cars or is it an option for a daily driver?

I'm not sure what you mean by deleting. If anything, you need to send the exhaust gas toward the road, or the exhaust gas will fry everything under the hood. Some will gut out the flapper valve in an "internal" wastegate like in that picture and weld the hole shut, or they'll leave it in there and just weld the flapper closed. Then they connect an "external" wastegate to the exhaust manifold instead. Then the O2 housing only has to contain the turbine exit flow (doesn't have to merge the wastegate flow).

Also, Is it true that in order to recirculate a manifold mounted wategate you must have piping from the wastegate to the O2 housing or downpipe? and can T3 turbos have a recirculated O2 housing?

Yes. If you want to be reasonably quiet, you need to plumb the wastegate flow back into the exhaust. Some have a dump tube aimed at the pavement (that stuff's very hot), but it will be LOUD. Keep in mind that at full boost (where you will be quite often if you have a lead foot like many of us), the wastegate is constantly open (that's why your boost stopped going up). And the exhaust coming out of that wastegate is about 18" from your exhaust valves with nothing in between. And you're under full load.

Another option is to gut the flapper so that there's just a hole. Then you get an O2 housing that does the normal thing with the turbine flow, but the wastegate flow goes from the turbine housing to an external wastegate, and the wastegate exit flow goes into another pipe that merges back with the turbine exit flow like in a stock configuration. This gives you much better flow out the wastegate than the flapper valves can offer (many of those flappers only open 45 degrees, so the flapper is still hanging out in the way of all of that exhaust flow). An obvious variation on this is to dump the exhaust after it exits the external wastegate rather than merge it back into the O2 housing flow, but you still need piping to get it down out of the engine bay under the car.

Sorry for the dumb questions but its a lot harder to learn when you cant actually see what youre talking about.

Here's another picture of my FPB28 just before install. The O2 housing is on the right, then the turbine housing, then the center section, then the compressor housing. The O2 housing outlet you see would be pointing at the road, and the compressor inlet and outlet (with paper towels stuffed in them) would be pointing toward the passenger side of the car. You can see by the shape of the O2 housing that there are two internal passages that eventually merge. The one farther from you is the wastegate, the closer one is the turbine exit. On the far side of the turbine housing, you can see the flange and two of the bolt holes where the exhaust manifold bolts to the turbine housing.

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There are trillions of pictures on this forum of every kind of O2 housing setup, wastegate setup, etc. You can also go "window shopping" online to some of the DSM performance shops to see what they have to sell. They'll have pictures.

Hope that helps!

 

[vtown661]

Ok so heres the plan and you tell me if Ive got it right.

Tubular mani with wastegate off the collector
Tail 44mm WG (Recirculated)
GT3582R (Doesn't have internal WG)
I would need a custom built piping from the WG to a custom built DP? Or can I buy these somewhere? I havent seen them.
And if I did this setup I wouldn't need an O2 housing?
Wouldnt this also remove the O2 sensor in that housing causing malfunctions? This is all for a daily driver in california so it cant be really loud (must be recirculated) and can't throw CEL (cant remove O2 Sensors, etc) but i dont care if its illegal cause basically everything is illegal here. I just dont want it to be obvious.
Am I better off just getting a custom piping connecting the WG to the O2 housing?

thanks for the replies everyone. and kenamond thanks for the visuals. BIG HELP.

 

[synthetek]

A GT3582R with no internal wg should just have 1 outlet , a custom downpipe could be made to attach to the outlet and that would eliminate the need for an o2 housing but you would still need an o2 sensor bung in the downpipe to install the o2 sensor.