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External Wastegate on a 9-3.

8K views 78 replies 20 participants last post by  Heath 
#1 · (Edited)
I will be keeping track of what I do to my car in this thread for anyone who cares...

This showed up today:




:mrgreen:

I found someone local who can weld cast iron, and the price should be sort of reasonable. I plan to vent to the atmosphere. If anyone has ideas or input that would be appreciated.

So to get started, I need a 9-3 manifold.

Anyone?
 
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#9 ·
Yay, I get to go see fuckface.


Anyway, I need to figure out what spring is in here, and then maybe get a new one.

I'm shooting for a peak of 28 or so on the new tune (eventually). What should my base be set at?

There is a 14 pound spring available. Base at half of peak, right?
 
#11 ·
Yay, I get to go see fuckface.

Anyway, I need to figure out what spring is in here, and then maybe get a new one.

I'm shooting for a peak of 28 or so on the new tune (eventually). What should my base be set at?

There is a 14 pound spring available. Base at half of peak, right?
For an external wastegate the rule of thumb is, your max boost should be no more than 7 psi more than the spring that you run or else you may experience boost creep.

I currently experience that issue in my c900 with a 8psi spring and 17psi max boost. You should probably pick up a 1bar spring.
 
#12 ·
Alright, good info.


I am going to take it apart tonight and see what's in it.

I am hoping for a bit better boost control with this.

Also, if anyone has any thoughts on how to bypass/hold closed the stock one, let me know.
 
#30 · (Edited)
I have read his thread several times. :)

I'm looking forward to it.

It's going to be tight in there with the pipe:




I'm going to have to aim the pipe for the exhaust through that little gap between the downpipe, and supply pipe.

I'm ordering an ebay pipe tonight, as well as the flange.

I'm also thinking about getting the mani coated with something.

I know jet-hot or whatever is sweet, but who here actually has experience with coatings?

I am not aware of anyone on here (besides Daveship) that has a coating.

Thoughts? I would really like to DIY, and keep the cost low.
 
#34 · (Edited)
Watch the placement of the WG. If you do it as pictued it will only pull exhaust from two cylinders and that can cause problems. Also venting to atmosphere is not the best idea for A/F at WOT, your not getting the best readings from your O2.
Here is how i did it on my manifold

Then i welded a flange on the end of the tube and pointed the WG down at the DP and routed it back in tangentially.
I agree with just welding the internal WG hole shut and then grinding and smoothing the turbo inlet to eliminate the turbulence it causes at the inlet. Did this guy mention anything about preheating the pieces before welding? Because he should be. Also watch what alloy flange you are having welded on. Different coefficients of thermal expansion leads to cracks.
I had the manifold coated by Jet Hot with their 2000 black series. It has held up pretty well so far, no flaking at all. Manifold has about 2 months or more of drive time, mainly at WOT of course. Only thing was it was pretty expensive, think it was like 400 in the end. I have measure the surface temp of the pipes after some WOT driving with a heat gun. Was around 450F on the surface in the middle of the primary. Which i think is pretty good for 0.065" mild piping.
 
#36 ·
Also venting to atmosphere is not the best idea for A/F at WOT, your not getting the best readings from your O2.
will not cause a problem since there is plenty of gases that flow past the O2 sensor and if there werent the turbine would not be spinning...

Second topic are the "environmental" issues if wented out to atmosphere and even if it may sound like you "polluting" you really arent since the WG is only open when on WOT and during which AFR is plenty rich and cat therefore useless since it does not purify at that time. It function best when afr stoich and its efficiency drops fast when afr moves away from stoich to rich.
 
#35 ·
ok, I thought I understood blow off valves, waste gates, how they work, what they do, and the differences between them.
But this thread makes me think I'm mistaken about waste gates.




I thought venting your waste gate to atmosphere was illegal? Something about how it's already gone through the combustion and is actually exhaust gas or something and because of that, by law, it must pass through your cat converter before venting to atmosphere. That's why the waste gate is supposed to dump the gasses in to the exhaust system, not vent to atmosphere (as apposed to BOV is BEFORE the engine, therefore it's just normal air, therefore it CAN be vented to atmosphere)


Please correct me where I'm wrong?
 
#39 ·
Lots of things are "illegal" in many places, but as Vigge stated, the external gate is only going to open when you are going wide open, and that is not how cars are tested for emissions, plus the emissions out the tail pipe would be unaffected by the wastegate venting out under the front end of the car.

...also, no emissions testing in many states.
 
#44 · (Edited)
Soooo, what you are pretty much saying is that yes. It's illegal, but no, you don't want to admit it? lmao
Venting before the cat has nothing to do with emissions CHECKS IMO since the very reason you pointed out.

It was my understanding that all gasses exiting the combustion chambers on a car MUST be run through the cat before venting to atmosphere. Per federal law.
Whether or not there is an environmental impact or whatever is not my question.

Per federal law, is venting a wastegate illegal or not?
 
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