I have a friend making me a custom O2 housing for my '89 GT and it's actually coming along nicely.
The custom O2 housing looks very similar to the ones made in the past with a divorced wastegate pipe. This will bolt up in the OEM location and enable me to keep my A/C if I still had it and will be 2.5" vs the stock 1 7/8".
Here are the bends being used:
Here is the jig made off the OEM O2 housing:
Here is the start of the new custom O2 housing:
All it should need now is some clean up and an O2 bung. The wastegate tube isn't as graduated as I anticipated, but I think it looks really good.
What sucks is I used to have a turbine, but scrapped it... If I get measurements, do you think he could fabricate the divider that way? How important is the indention/flat edge around the wastegate port on the flange? Like this one pictured. I assume it's for the the wastegate to fully open. With the larger hole of my setup, do you think it'd be fine without the indention?
If you get him measurements he should be OK.
He can make it a little bigger than the measurements indicate and then you can adjust the divider to suit upon assembly.
BTW, It really only needs a couple of decent tack welds to attach it to the flange, allowing you plenty of room to adjust it to fit.
The milled area next to the Waste-Gate port is to allow the wastegate flapper to open fully.
Depending on the size of the WG port on the flange you have there it might not be neccessary.
You'll have to check the WG range of movement upon assembly and possibly grind with a burr if required.
I was able to pull a turbine housing and sent it off to my friend. The wastegate actuator moves the flapper roughly 1/2" and once fully open, does break the surface where the flange would meet the turbine housing. So he'll know for sure now if the area next to the waste gate port needs milled or not and will be able to get the divider just right.
Once he makes mine, sends it to me & I get it installed to see if there are any bugs to work out, he intends to make more if there is a demand for them. He thinks he'll be able to sell them for ~$150.
Gavin, I sent my friend several links with examples of what I wanted and he basically combined your waste gate pipe design to Jake's final design and that is what he came up with. It looks great! Thanks for the link to that other thread. I had not come across that one yet. Lots of great info!