oxygen(o2) sensor & wideband sensor placement

[Kronprinz]

I picked up an AEM wideband gauge and I'm going to get a custom exhaust built, and I want to know what is the best placement for the o2 sensor and the AEM wideband sensor. ECU will have second o2 delete, so no need to worry about that.

How far away from the turbine housing do these have to be, any certain angle, and what is the distance these two sensors be in relationship to each other?

[redline380]

Primary must be before the cat. If there is no cat, it can literally be anywhere. Just make it in a convenient spot to get at. At the least, I would have them staggered so they see plenty of flow, and the primary should be first in line since it is the most important.

[GrapeBandit]

too close it over heats, too far away it can collect condensation.
best angle is anywhere between 10 o'clock and 2 o'clock.
in relationship to each other, stagger them and keep them at least 2" away from each other

all of this sbould be in the instructions from AEM, or at least I would think so

[MetalMan]

Think I remember reading that somewhere around 10-12" after the turbo is a good location. I agree with Grape, keep it between 10-2 o'clock, otherwise it can be affected by condensation.

[Kronprinz]

The AEM is still in the mail, so I can't read the instructions, but they probably have them on their site, but didn't think to look until now
Car is going to be catless too.

Either way, I still needed to know the best placement for the stock primary o2

[Kronprinz]

I see some of you guys going with 3" downpipes and 2.5" the rest of the way. My plans are for a full 3". Is there any reason I shouldn't do a 4" downpipe and 3" the rest of the way back? lol bigger is better in this case, no?

[Wrath And Tears]

I believe the reasoning is fitment. Not only as it goes down by the transmission but also how it connects to the turbo / cat / test pipe. If it was all V-band I could see it working but I don't think a 4inch flange would mate to a 3 inch flange (obviously if you do some weird shit like adapters and whatnot it could work, I don't have experience with that though). Probably some other issues too.

[Avant Nate]

I think you see diminishing returns for go larger than 3". Plus its going to be a really tight fit for 4". How big is your turbo?

[GrapeBandit]

I dont think theres diminishing returns. the best exhaust for a turbo is the one with the least restrictions, or no exhaust at all. I dont see anything wrong with going big post turbo, you want all that air thats already past the turbine to GTFO there as quick as possible, reduced back pressure. now if we were talking runner size on a turbo manifold, thats another story