O2 Housing Problem

[gilmac1010]

So I had my car up on the lift today... The stock downpipe was being held
on by two shouldered nuts to the stock 02 housing... I tried to put on
a 3" diameter downpipe after getting the stocker off.... Firstly I couldn't use
the shouldered nuts because of not enough clearance between the studs and
the fatter pipe. Then I found some "thinner" (not shouldered) chrome nuts
and barely got them on with a stubby wrench... But now the exhaust gases
are leaking somewhat from that connection? I have a Garrett/Bullseye N trim
turbo (16 or 18G?). I'm wondering if I should put an O2 housing with a wider
space between the studs on? Will the exhaust leak at the O2 housing mess
up my turbo? (I ran it for about ten minutes to get it home). Open to any and all suggestions. Thanx. Gil

[Kibo]

The OEM downpipe nuts are not shouldered, but they are self-locking. You may have better luck getting the OEM nuts to fit as they are likely smaller than what you are using now.

Your exhaust leak is more likely due to a blown/damaged gasket or a warped flange on the downpipe. It could also be due to the construction of the downpipe (i.e. the flange might not be at the correct angle, for example).

An exhaust leak after the O2 housing shouldn't adversely affect your turbo, although it may be close enough to the O2 sensor that it will affect readings (especially if you have a 2G O2 housing).

I suggest buying some OEM downpipe nuts, perhaps a new gasket, and check the downpipe flange for flatness.

FWIW, a stock O2 housing can't really be ported beyond 2.5" (and that's doing a bellmouth port)--so while a full 3" downpipe is easier/cheaper to make, it just makes it harder to fit to a stock O2 (as you've found) without any real performance benefit over one that has a nice taper to 2.5" at the O2 flange.

[Wazzelby]

Hey Gill, just give me a call and we'll fix it like we talked about. I can't do it this weekend because of my wedding reception... Next weekend though, we'll get it taken care of.

[gilmac1010]

Thanks Erik and Allen

[biglady112]

How did you finally get it done? I have run into this problem alot as of late.