atmospheric o2 ?

[bluetlr2001]

I have a sort of newbie question about an o2 dump i just installed. The question i have is when the wastegate opens it sounds like an n/a motor with an open header. Im not sure if its suspossed to sound that way because ive not got to hear one on a turbo with an internal wastegate or external for that case. But i know i installed everything right plus i put on a tubular manifold when i done it. But im just wondering if its suspossed to sound that way? Thanks in advance for your input.

 

[stevew1]

Yeah, it basically sounds like a car with open headers..really loud, and can't really hear the turbo spool sound.

 

[ilikespeeding]

Resonator FTW.

 

[420a-t]

Where would you put a resonator? Doesn't it dump about a foot away from the wategate flapper?

 

[ilikespeeding]

Where would you put a resonator? Doesn't it dump about a foot away from the wategate flapper?

You can get it modified so that the pipe drops under the car, which is where you'd throw a resonator on.

 

[Mr Peepers]

I was thinking about an O2 dump to help with boost creep but the sound kept me away from it. There is a thread about using motorcycle mufflers etc to muffle the sound, it would be put somewhere on the dump tube.

http://www.dsmtuners.com/forums/showthread.php?t=149544&highlight=o2+dump+muffler

 

[420a-t]

Good to know! i was going to get one of the one's on Ebay, but i didn't want the annoying sound muffling up the turbo spool, just like stevew1 said. I know a 2.5" housing wouldn't be as good as a dumped housing, but is there really that much performance difference that people would get the loud dump over it? Just wondering what everyone's thoughts are.

 

[Mr Peepers]

It's not so much performance as boost control. With our stock O2 housings the WG is recirculated way too close to the turbine outlet IMHO, causing turbulence. Also, the fact there is near zero backpressure behind the WG, much more exhaust gas can be bypassed.

 

[dsm-onster]

All this talk about lengthening the dump tube and adding a resonator or muffler. Why not recirculate way later in the exhaust system. I don't see that much difference in price. But the noise would be nulled completely. And likely it would perform nearly the same.

 

[Mr Peepers]

A rule of thumb is recirculating no less than 18" from the turbine outlet. The problem I see is welding it to the downpipe and still being able to take everything apart again. I haven't heard of many DSM's recirculating their dump tubes once they go to external. I'm curious how much better(if any) an o2 dump routed back farther in the exhaust is than a ported stock housing for boost creep.

 

[bluetlr2001]

Well iim glad thats the way way its suspossed to sound but it is rather annoying exspecially for an everyday driver. If i had known how loud it was going to be i wouldnt have wasted my time putting it on. But the performance difference it maybe was unbelieveable. As soon as it starts spooling its at full boost but ive got to check everyting today because i had my ebc set on 12psi but since i put the o2 on it spikes to 12 but drops down to 10 and stays there. So either its boosting less now and im gonna have to turn it up or oe of my vaccum lines is leaking. But with the 2psi missing i cant even tell a difference since its dumped. I havent tried 14psi yet im going to make sure i dont have any oil or water leaks first. But i hope this thread helps some people out as to if they wanted a o2 dump but didnt know how noisy they were. If i get a chance ill try to record it and post it so you can get a little bit of how it sounds.

 

[dsm-onster]

It's not the dump that's giving you more power on the butt-o-meter. It is the better flowing o2 housing. All the dsm oem 02 housings are poorly designed.

I'll take that back. Perhaps a little performance gain comes from not reintroducing the wastegated gases back into the exhuast stream right after the turbine. This casues turbulance and slows spool a little. But likely little increase will be noted when running a "street" turbine wheel. Most of your gain is likely from the better flow out of the turbine.

 

[bluetlr2001]

Well i think im going to pull the o2 dump back off next week and sell it if anybody wants it. But im going to port my o2 housing first so it will flow alittle better.