salemetro

iTrader: (5)

Fabrication is near done for the hot-side piping on my FI setup, but I'm left needing to locate the front O2s. Some have suggested to me NOT to place them right off the ends of the manifolds (before the turbo), as the thought is that it will be too much heat for the 02s to handle, and will ruin them, and possibly ruin the turbine in the process.

Is it best to locate them on the turbo downpipe? If so, how far down the pipe is best?

I've been looking around a bit for pics here, but have not had much luck yet.

91sbcamaro

iTrader: (3)

I would like to hear some suggestions on this as well. I will be finishing my merge this weekend.

XtremeDime

iTrader: (16)

Front o2s should be before the turbo, otherwise you wont get accurate readings. The purpose of the o2 sensors is to get a reading off each bank. Putting them after the turbo would defeat that.

salemetro

iTrader: (5)

That's exactly what I thought...and it makes sense. But, I've also been told that the extra heat produced by adding a turbo will destroy an O2 if it's placed too far upstream. Is this total mis-information?

XtremeDime

iTrader: (16)

The heat should be roughly the same going to the turbo, the downpipe is extremely hot though.

salemetro

iTrader: (5)

I've been doing a bunch of searching, and am finding a whole slough of "answers". Some companies are saying "no closer than 18" from the exhaust port, while some say 36"...and still others say to place them roughly a foot down the downpipe.

Anyone else have any thoughts from real-world/ personal experience?

I'd love to be able to put them right at the collectors, before the merge... but if I can't, my only other option is to place them on the downpipe across from each other.

RexDiablo

I think my downpipe temp is way lower than before the turbo, because of the big reduction in pressure..
Off topic, but do you really need the o2`s when going FI and sd tune? When im only using the wb o2 to tune?
On topic, I would also like to know where people have theire NB o2`s! In one of our turbo ls1 nissans we have them just after the manifold "log"

XtremeDime

iTrader: (16)

Well stock they arent that far from the exhaust port and I believe the turbo will generate more heat than anything on the car(2 exhaust dumping into it and spinning around, generates even more heat). Im told 18" on the DP also for an o2 sensor because the turbo is so hot. Widebands can handle more heat than a narrowband o2. I would say put it just after the manifold in the cross over.

XtremeDime

iTrader: (16)

SD has 2 types: Open loop and closed. Open loop uses no o2s but the o2s help to correct for fluctuations, basically when you have an OL tune thats it, nothing will ever change in it. With a Closed loop it uses the o2s to make minor changes in the a/f. Generally an SD tune will utilize both, at start up it will use OL, at part throttle it uses closed loop and WOT is OL. Im running open loop currently but Im thinking of adding o2s because they are a great tuning tool.

RexDiablo

Thanks for clearing that up !=)

XtremeDime

iTrader: (16)

Im not an expert but that gives a general idea, I try lol

salemetro

iTrader: (5)

Stock location means nothing when you are increasing egt's by a BUNCH due to the turbo increasing the engine's output....and the turbo is hot BECAUSE of the much-hotter exhaust that is feeding into it?? Don't get me wrong, cuz I'm not trying to sound shitty here...and I'm most certainly not un-appreciative of your comments. It just appears that you might be (if I'm reading your replies correctly) saying that the turbo is hotter than the exhaust gasses that are up-stream.....which does not make sense to me. Or, does the friction from the "swirl" in the turbine housing increase temps a bunch?

XtremeDime

iTrader: (16)

Its thermodynamics, youre taking 2 exhaust streams and spinning them in a turbine. Of course its going to generate more heat. I realize the manifolds will be hotter due to the extra output but how often do you think youre going to be in boost? Have you ever seen a hard run and look in the engine bay? The turbo is glowing red hot, it takes a hell of alot more for the manifolds to do that. o2s belong in each bank, without them being their you may as well run a single wideband in the DP and not even run o2s. Theres no way to run o2s after turbo and expect those readings to help you at all.

salemetro

iTrader: (5)

Just a cool pic I found....might help illustrate heat dissipation...

salemetro

iTrader: (5)

I was just thinking that maybe the manifolds were better at dissipating the heat, since it is half of the volume that the turbo sees...but that the egt's were higher up-stream of the turbo?

Bottom line is that I've heard rumors of people wasting o2s in a rapid fashion when up-stream of the turbo, and I'm not sure if it's true or not. I just don't want to make a poor choice on where I locate mine. Anyone else have issues running them near the exhaust collector??