hey guys i have a spare 1g o2 housing and im thinking of building an o2 dump out of it (why the hell not). i was wondering if anyone has one and can give me the dimensions of the dump tube. thanks.

You can do it however big you want. I had a tubular o2 with dump. The dumptube was about 2" big I think. Make it as big as the wastegate side of the turbo. FYI they sound like shit.

thats ok how they sound its more of a one day type thing to make some noise and i can build and get materials for free. i was just wondering because i didnt want to make it too long. i thought that if the pipe was too long i would creep like a bastard..

who knows, maybe for comedy ill add a windy noise maker deal just to be dumb

I think they sound sweet... but Im sure as a DD I wont like it too much, but how often do you boost wot? ;)

true, plus i always run 8-10 normally anyways..

My dump tube is 1.75". It ends right at the cross brace. There is a slight notch in the crossbrace on an AWD that looks like its made for a dump tube. I would have it end right there.

Internal wastegates open before full boost. They get annoying. Lets put it this way. You cannot make the 02 dump pipe too big. If you make it too small you risk creeping. 8-10 psi would be really annoying driving around with a dump.

For another reference, here is a huge thread on Tuners all about O2 housings that is quite interesting: http://www.dsmtuners.com/forums/showthread...25&pagenumber=1

thats why i set my car to just driving around, if i feel like it i can just dial in 10psi more.. when i drive i grandma it anywas and dont even have to hit boost. wastes gas..

hey chris, whats the size of your exhaust elbow? still about the same size as the stock one?

The largest dp flange that will bolt up is 2.5" so that would be the optimal size. You could try and go larger but I am not sure you can. Are you cutting the flanges off and welding on new pipe? If so, this may not work depending on the metals you use. The stocker is cast. You can buy flanges seperatly or make your own. I wouldn't cut the old one.

My O2 dump is 2.5" from the turbine outlet to the downpipe. A stock 1G )2 is only 2". I think a 2G O2 is 2.5 though, or close to it.

i work at a metals shop so and we have scraps of stuff laying around in a huge pile of tubing. im just gonna plasma cut that wastegate part off and clean up the resudual because i dont want to cut into the exhaust elbow and then just weld on a pipe..

Yeah I'm also looking into to making an 02 dump. I have a friend that made one out of his stock 1g 02. He said it sounds great when he boosts and it added some power. It helps a lot by venting the wastegate gases somewhere else so it doesnt create unwanted turbulence with the exiting turbine gases.

Please don't state incorrect facts. That is a big pet peave of mine. You can go up to a 2.7" hole before you start running into problems. There is still more room to go on the 3 sides away from the WG port. I had a 3" HRC that I had ported out to almost a full 3" and I will be making a custom one that is a full 3" in the next month.

Also welding onto cast iron isn't a huge problem either. Cast steel would be better, but it should still hold fine. Really crank up the gas on the welder though, there are quite a few impurities in the cast iron.

Its not a problem of turbulence, its a problem of waist gate flow. The passage starts out nice and big but gets narrowed WAY to much at the end with a 1g or a 2g o2housing. The best place to recirculate the waist gate is at least 16" from the turbo. And 1.5" pipe works great for the waist gate dump. Also this is done to help eliminate boost creep. Not to sound cool.

~John

this is why im going to do this.. i guess on the avc-r i can set up the duty per every gear but its too big of a hassle. thanks for the info guys

im planning on ending the dump tube a few inches after the o2 housing/downpile flange. i was accually thinking instead of going with the 1.5 since the hole is bigger than that from the wastegate entrance seems to be bigger than that, not to mention its more oval. think 1.75 will still be ok?

As long as you have enough room for the 1.75" pipe, which you should. Bigger is always better, in this case.

~John