i was wanting to know if this has any effect at all on your a/f ratios...i have a drag manifold and u would think that exhaust gas going into atmosphere would not be read by o2 sensor, in turn giving inaccurate a/f.... idk, i just wanted to see what some opinions were cause i searched and found nothing..

 

I imagine it would have a effect with tunning cause the open wastegate is just going to be dumping Dirty air right back into the path of the turbo and the turbo is just going to suck the dirty air back in.
Not to mention it will make your engine bay filthy.

 

Were you planning on putting a WBO2 sensor in your dump tube too?? Cuz otherwise open wg will be the same as having a dumptube with reading your AFR, and only some of your exhaust goes out the wg, not all so your wideband still reads. But yes, it can get the exhaust sucked back into the intake or make it dirty, but i am not running a dumptube now and i know other ppl that have done that with 10 second cars no problems.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by inspector01 &raquo;</TD></TR><TR><TD CLASS="quote">Were you planning on putting a WBO2 sensor in your dump tube too?? Cuz otherwise open wg will be the same as having a dumptube with reading your AFR, and only some of your exhaust goes out the wg, not all so your wideband still reads. But yes, it can get the exhaust sucked back into the intake or make it dirty, but i am not running a dumptube now and i know other ppl that have done that with 10 second cars no problems.</TD></TR></TABLE>

Ya that is true. but more power can be found simply by routing a dumptube out of the way of the intake

 

what i meant was, does the exhaust that escapes have any effect on the exhaust going to the wideband?

 

you have a river... the river has a fork in it

is the water on the right the same as the water on the left? yes

now im not sure about a divided manifold style setup...

 

Bottom line is it will work fine. Plenty of people have been doing it for over a decade now.

The exhaust gas composition isn't going to change at all when you are all full boost dumping your wastegate to atmosphere. Say you have 5% O2 in your exhaust (hypothetical). You hit full boost and some of the gas is bypassing the turbo/exhaust and exiting to atmosphere. This ejected has has the same composition as the gas going through your exhaust, and won't change the reading from your wideband any significant amount.

 

it will run fine......as long as you have the wastegate dumping well away from the turbo inlet... ive seen 80+hp gains on cars that didnt have a good blowdown tube on it...turbo is pretty much sucking in exhaust gases

 

I know when we were tuning my car we were not getting the numbers we expected to begin with. After some time consuming troublshooting we determined my turbo was sucking up a ton of hot dirty air out of the wastegate and we routed a dumptube to about the same height as the bottom of the oil pan. Next pass saw a significant gain in power.

 

thats pretty interesting..mine was a little past my oil pan so i didnt have any probs...i think this time i will try to run it under the engine so it wont be so loud..thanks for the info!

 

Im running really rich with a FMU and 12:1 disc and it's dumping rich soot out of the wastegate and it seems like my boost has substantially diminished. If I turn the wastegate over and have it point down instead of up will that help or do I defientely need a dump tube from the wastegate to under the car? Also, can a wastegate get plugged from the rich condition?

 

The wideband o2 measures the ratio of gas/oxygen particles, not volume. So as long as there are no new elements introduced into the exhaust, the ratio will not change. Wastegate is only open under boost pressure, that means the pressure of the exhaust gasses is also rising and flow, and there is no physical way that the fresh oxygen can get back into the manifold through the wastegate/dumptube and be read by the o2.
Just my .02