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Old 05-07-2008, 06:33 PM   #1
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Default Wastegate flange question

I am getting a custom downpipe flange made by weirtech so I can run a separate wastegate dump pipe. I could only afford a 2.25" exhaust and want to compensate for it.

My questions are this:

Where should the dump pipe hole be placed with respect to the wastegate itself?

1) Concentric with the hole. (red circle in the pic)

2) Offset from the hole a little bit towards the turbine side. (blue circle in the pic)


What should be the size of the hole? 1.5" ? 1.25" ?




(2) makes more sense to me, because as the wastegate opens, the plate would still be blocking the hole on the far end of the flange, wouldn't it? I cannot imagine that the actuator rod would travel more than 0.5" in any case.
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Old 05-07-2008, 06:38 PM   #2
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Don't a lot of divorced WG downpipes have a little curved section welded onto the inside of the flange to prevent disrupting the flow into the main pipe? If so, the red would be better to clear the tab.
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Old 05-07-2008, 06:47 PM   #3
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I'd do it offset purpendicular with the axis of the flapper lever shaft since that is the part will be open first and the most. That would make it slightly above the blue circle.
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Old 05-07-2008, 10:34 PM   #4
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Wouldn't it be easier to just buy a flange that fits your turbo?

I think the propr flanges do seal off the two ports.

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Old 05-08-2008, 11:55 PM   #5
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please explain to me how that flange seals off the two ports from each other... there is nothing portruding into the exhaust housing.

i'd put the hole toward the hinge point on the flapper slightly. it really depends on how you want to route it back into the downpipe. also, check for clearance on the flapper to flange surface. open the flapper and make sure the hole is in the location of where it sticks out past the flange mating surface of the housing. that is, if it opens that far to begin with. i've done flanges that had a relief cut into them to allow the flapper to open, and then just merge directly at the flange, but i've also done downpipes that had a slight merge and ones that had a compltely divorced merge.

here is a reliefed flange:




here is a slight merge off the flange:



here is a completely divided:




obviously you will realize the most gains with the completely divided setup, but keep in mind, there should be something seperating them inside the exhaust housing.
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Old 05-09-2008, 12:46 AM   #6
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uhh do a 2 inch off the wg man and run it back into the dp like and you should be jsut fine
i wonder how much a custom flange and DP is vs getting something made 3 inches though hell the mats cant be outraguesly more. The mo flow the better trust me dude.
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Old 05-09-2008, 11:24 AM   #7
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Quote:
Originally Posted by weiRtech View Post
i'd put the hole toward the hinge point on the flapper slightly. it really depends on how you want to route it back into the downpipe. also, check for clearance on the flapper to flange surface. open the flapper and make sure the hole is in the location of where it sticks out past the flange mating surface of the housing. that is, if it opens that far to begin with. i've done flanges that had a relief cut into them to allow the flapper to open, and then just merge directly at the flange, but i've also done downpipes that had a slight merge and ones that had a compltely divorced merge.

obviously you will realize the most gains with the completely divided setup, but keep in mind, there should be something seperating them inside the exhaust housing.
Gotcha. BTW I was imagining it will be completely separate and dump into atmosphere via one of these:

http://store.summitracing.com/partde...5&autoview=sku

I thought this would be the best way to compensate for my 2.25" exhaust. But now I will have to re-think because I just realized its a lot of work to route an additional pipe.

Maybe I will do it the way magna quoted in his post.
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