"stock" o2 not bolting up!?!

[Gregory]

Okay, I bought a EVO III 16g with ported stock o2 housing from a guy. I took the t25 off last night, and was putting the 16g on this morning. He assured me that the o2 housing was stock, and it should bolt up to the dp no problem. It was just ported. I do believe him since he is a reputable seller/buyer and proven member on dsmtuners, but my question is, is there some differences between a 95 gsx and a 98 gst? My dp flange is not as big and will not reach both studs on his O2. Do I need to buy exhaust now? Or do I need to put my old o2 housing on the 16g (if that will work)??? Does anyone know? Please help! Thanks for anything. You guys are awesome!

 

[Gregory]

okay... I just got an e-mail from the guy and he says it was off of a 97 gst... so now I'm really stumped... Please help!

 

[EclipseTrbo420A]

they should all be the same. just keep at it

 

[romeen]

It sounds like you may have gotten an EVO 3 O2 housing which is considered an upgrade over the stock housing. It has a larger bolt pattern and different angle than the stock housing. It's best to use a DP with the correct flange and flange angle with it (RRE has some nice ones) but it is possible to make your current DP work. You can either have the correct flange welded on in place of the one that is on there right now or you can cut the bolt holes into slots to allow it to mate up. If you do this it will put stress on the flex section and it may eventually fail. Here is some info copied from RRE's website:

EVO III O2 Housing:
These are BIG. They have a larger inlet hole for the turbine flow, larger wastegate passage, and a larger outlet. The bolt spacing on the outlet flange is wider, this makes easier to adapt a custom 3" down pipe. They have a slightly different angle at the DP flange. If you already have a 2.5" DP with a slotted flange, it is _possible_ to bolt it up to an EVO O2 housing. Usually it will stress the flex section too much so it should be considered a temporary solution only. We include a larger flange and also the larger inlet and DP gaskets with the O2 housing to make things easier for you.

For more info scroll about halfway down here:

http://roadraceengineering.com/eclturbos.htm

 

[Gregory]

hey. those sound like good ideas, but I don't understand why it would bolt right up to his stock 97gst? I mean, he took it off his car after I bought it, so i def think that's where it came from. can I put my o2 housing on the 16g? I don't know if I want to ruin my dp. If I can put my o2 on, will that be a bad mix? Like dangerous for the car or anything? I figure leaving that o2 housing with my dp will just create a lot of turbulance in the exhaust since it will be feeding from a larger hole into a smaller hole. Thanks for the help You guys rock

 

[Gregory]

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that is the new

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that was the old

 

[romeen]

Is your friend the original owner of the car? Is it possible that someone before him upgraded the O2 housing?

Looking at your pictures I am confident that the O2 housing you got is an EVO 3 housing. I have my stock, unported 2g housing sitting right here. I just measured it and it is identical to the one you show in the 2nd picture.

On the other hand the first picture clearly shows a 1/2" larger diameter outlet, larger flange and larger space between the studs. All of these are consistent with and EVO 3 housing.

If you have access to a die grinder then probably the most economical way to go would be to port out your stock housing and sell the EVO 3 housing as they are a desirable piece. I don't think it will hurt the engine to use the stock housing with the EVO 3 turbo but it will negatively affect performance and cause the turbo to work harder. Like you mentioned you really don't want any exhaust components going from a larger diameter to a smaller diameter. You can use an EVO 3 turbo to O2 housing gasket to gasket match the inlet of the O2 housing. While you're there you may as well enlarge the wastegate passage to help with potential boost creep.

FWIW, I am using a Buschur DP (standard flange) with my EVO 3 O2 housing. It definitely does put stress on the flex section but mine has held up for 2 years this way w/out leaking. Having said that I already have one of the RRE DP's with the EVO style flange waiting to go on as soon as I get the appropriately sized cat back portion.

Here is another paragraph copied from RRE:

If you have the upgraded EVO O2 sensor housing, order the EVO style DP. It comes with the larger EVO bolt pattern and is angled correctly for those cars running the EVO O2 housing

Hope this helps.

 

[Gregory]

Thanks Romeen! To clarify... I have to use the EVOIII gasket between the 16g and the stock O2 housing? I have everything I need, right? I don't have to order a new gasket?

 

[Gregory]

can anyone help me with what i'm askin?

 

[romeen]

Thanks Romeen! To clarify... I have to use the EVOIII gasket between the 16g and the stock O2 housing? I have everything I need, right? I don't have to order a new gasket?

Yes, I believe you should use the EVO 3 gasket. Place it on the O2 housing first just to make sure it lines up correctly and that no portion of it will be sticking out into the exhaust stream.

 

[Gregory]

Yes, I believe you should use the EVO 3 gasket. Place it on the O2 housing first just to make sure it lines up correctly and that no portion of it will be sticking out into the exhaust stream.

yea, that all looks good, but it looks like the stock o2 housing is a little smaller than the evoIII turbo. It seems to be bolting up good, but will just have some turbulance similar to what we were saying about the downpipe.

 

[romeen]

yea, that all looks good, but it looks like the stock o2 housing is a little smaller than the evoIII turbo. It seems to be bolting up good, but will just have some turbulance similar to what we were saying about the downpipe.

That's right. The turbine outlet of the EVO 3 is a little bigger than the outlet of a small 16G or T25. The EVO 3 O2 housing matches that. Thats why in post #7 I recommended using the EVO 3 gasket as a template to port your stock housing so that you won't be going from a larger diameter to a smaller diameter.