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Old 10-19-2001, 10:34 AM   #1
Force[FED]
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Question Wastegate dump on stock exhaust???

OK, so I was looking over some of my pics, and I noticed that with the stock exhaust, there was no opening in the downpipe to allow the wastegate opening to flow. Here is a pic:





Now, if you look at the BPM twin dump downpipe, you can clearly see where the wastegate flapper dumps out:





So this leads me to ask (and I should have looked more carefully when doing the install, tho we were rushed)...

With the stock exhaust, where the heck does the exhaust from the wastegate go? Even if the gate were to open (which it obviously does), where does it flow? Or is there JUST ENOUGH pipe exposed to the wastegate area to allow it to vent? If so, it must be VERY small (look at the pics!). I would imagine this would make it very difficult to control boost effectively with stock downpipe.

Am I missing something? I even looked at the stock downpipe off the car...the flange opening appears to only flow by the turbine, and the flange is flat over the wastegate opening.

Kevin
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Old 10-19-2001, 10:38 AM   #2
RiftsWRX
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You hit it on the nose.

Since the wheel and wastegate are recessed about an inch into the flange, that is where the wastegate gas travels.... RIGHT INTO THE PATH OF THE TURBINE GAS


Subaru did a good one on that

Jorge (RiftsWRX)
www.ProjectWRX.com
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Old 10-19-2001, 10:42 AM   #3
Force[FED]
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Thanks Jorge...I was actually rereading my post, and I remembered looking at the turbo during the install and noticing the exhaust turbine and wastegate flapper being recessed into one large area on the turbo. I was gonna edit my post, but figured I would see what people said first.

That just goes to show how CRAPPY the stock exhaust setup is. Ughhh, no wonder this exhaust owns me! :P The turbo is also much more 'vocal' with the new exhaust, it makes this amazing super-high pitch whine whenever I get on the throttle.

Thanks Jorge!

Kevin
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Old 10-19-2001, 11:05 AM   #4
Imprezd
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whose the bone head under the car?
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Old 10-19-2001, 11:14 AM   #5
Jaxx
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yup you are correct

here is a pict of stock compaired to an APS down pipe


but remember the wastegate does not open like a throttle plate ..
it swings open like a vault door
so unless it is fully open, air comes out of the wastegate port hits the wastegate door and deflects into the turbine discharge

this the what the dual vent down pipe (like bpm) tries to solve
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Old 10-19-2001, 01:00 PM   #6
Force[FED]
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That's my large mullet under the car, we were mounting up the downpipe (I was under the car, my brother was working from the engine bay).

I know the wastegate door is a 'flapper', but it's still a very crappy design. Makes perfect sense why the BPM downpipe flange also looks like this:



The extra piece welded perpendicular on the flange is to ensure that the wastegate flapper and turbine areas on the turbo side are seperated. Duh...nothing like finally piecing it all together mentally!

Kevin

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Old 10-19-2001, 05:05 PM   #7
TypeC
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sweet! Nice pics!

looking at those, just a DP alone should yield good gains w.r.t. boost spiking and overall effeciency.

Hmm, maybe it IS time to do the exhaust.

-C
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