Hi everybody, I would like to know the difference between the two, where you would install them and how they work. If anybody would be able to shed some light on this for me, it would be great. Also, which one provides more power? I know the external wastegate holds boost better, but does it help in anything else? also does the o2 dump act like a open downpipe?

 

can anyone help me out? any information would help!

 

Internal wastegate. This is what comes on our stock turbos. They work fine in general for "low boost" applications.

External Wastegates are an "improvement" because they are not size limited by engineering constraints in turbocharger design. It does the EXACT same thing as an internal wastegate, but instead of being built "into" the turbine, it is attached externally onto the manifold. Being that our cars are twin scroll some aftermarket manifolds are also twin scroll and run a dual external wastegate setup. An external wastegate is typically recirculated into the exhaust stream via the O2 housing. This is "bad" because it adds a burst of air to an otherwise smooth flowing exhaust stream. This creates turbulence and backpressure and as such MAY limit horsepower.

Having this dump externally is an ideal way to eliminate this backpressure turbulence.

External wastegates need to be installed on the manifold and as such, you'll need a manifold (typically). An O2 dump goes in place of your O2 housing. The O2 dump doesn't act like an open downpipe per se, you'll still have and be utilizing your full exhaust, the only thing being vented will be the gases escaping when the wastegate opens.

 

Man, ProPilot04 is rocking the informative posts today.

 

+1

 

+2

 

I always wondered the same thing, thanks propilot, great response!

 

Same here, thanks for the info.

 

thanks for the great information propilot +3 man! lol this helped out a lot, i didn't know the external wastegate was "bad"

 

^ I think he is saying an external wastegate is a good thing, not bad.

 

lol thanks guys... I'm just bored at work.

External gates aren't "bad" per se... each of them have their pros and cons.

On one hand, the internal wastegate is cheap, but it also throws its air back into the exhaust creating turbulent backpressure. It also takes up space on the turbine housing. On my Evo V I ran an external gate on the stock turbo. But I welded the internal wastegate flapper closed. This is always an option, but you risk the possibility of blowing the welds off at some undetermined time and making things VERY exciting.

An external gate is "nicer" than an internal gate because it can be designed in whatever way the engineer wants without having to conform to the turbine housing (because its obviously external). But it is still doing basically the same thing. The unit itself may be more efficient, but its still recirculating exhaust back into the exhaust stream creating the turbulent backpressure. UNLESS.

You route it to dump externally. This is (as far as performance goes) the "best". Not only do you have the external wastegate, but you have the exhaust gas from the gate venting through its own little dump. The only drawbacks are emissions, heat and exhaust in a new place, and noise.

But this doesn't necessarily mean you should all run out and purchase external O2 dumps...

 

I realize this is a very old thread but my question is what about turbine housings with the waste gate flange molded into the housing? Is that so you can run external gate with a stock manifold?

 

Yes. Cast manifold T3 kits have something similar as well.