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Old 12-14-2006, 09:32 AM   #1
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Default External Wastegate regulate boost on downpipe?

I'm running an HKS manifold and a external Tial 38mm. The piping is killing me and I was curious if I could redo it and weld the WG flange on the down pipe so it's more out of the way versus running it directly off of the turbine flange. Then cut the piping off the turbine flange, block off the hole, weld my wg flapper shut and run er like that. I have no idea if it would regulate boost or not though. What's everyones thoughts on that because I've never seen it being done obviously because it's not an efficient way of doing things. I'm running a straight dump pipe so no it wouldn't be hard, I don't have to reroute a reintroduced pipe down stream, just drill and weld.
BTW, this isn't a permanent setup by any means i'm just curious, because I'm not exactly sure how it would or would not work that way.
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Old 12-14-2006, 09:42 AM   #2
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it needs to be able to relieve exhaust from the turbine blades, so I don't see how it would work off the DP.
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Old 12-14-2006, 10:26 AM   #3
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I'm considering an external gate off the turbine port. Is there absolutely no way to get the gate over between the head and turbine? It looks like it could fit right behind the dp and the dump right in to the top of the dp where it drops down. I think you could just fix what the PO started. Looks to me like somebody just took the easy way out on the fab part of the project. While apart, you could port your turbine wastegate exhaust port.
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Old 12-14-2006, 10:54 AM   #4
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ive seen two setups like that for DSM's





any con's to doing it this way?
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Old 12-14-2006, 11:11 AM   #5
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That dsm picture you have is pretty much exactly what I have minus a about 2 ft of tubing to the WG and it works just fine when it comes to controlling boost, though it's not ideal. Mine dumps to atmosphere just like that below the car. What I have on the car right now, is the standard 5 bolt with a open wg port and a divorcer plate welded in the turbine housing itself. Imagine taking the divorcer off the BEGI DP and welding it in your turbine housing. Anyway what I want to do is just swap in an SR20 T25 that I got used. I'm curious as to wether or not I can weld the flapper shut on it though because if then the only way the wastegate would see any boost would be from the turbine wheel outlet. I guess I could just weld a divorcer in my downpipe and leave the WG port open again untill I redo everything. I just hate my setup and anything that has to do with relocating the WG should be a good thing in my case.
Unless anyone wants to weld a WG flange to my cast HKS manifold.
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Old 12-14-2006, 11:19 AM   #6
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Oh- I get it. Putting an external gate flange on the bottom - underneath the turbo mount is a good idea IMO. There's lots of room under there to run the wg dump pipe back into your exhaust dp on the underside- right?
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Old 12-14-2006, 11:25 AM   #7
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Yeah plenty, problem is welding mild/stainless flanges/tubing to a cast iron manifold.
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Old 12-14-2006, 11:27 AM   #8
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I didn't get it at first, but Ahh that is a good idea. I don't even know why he'd have to run the wg dump into the dp ie "completely divorced".
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Old 12-14-2006, 11:55 AM   #9
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welding the flapper itself will be tough BUT ive seen people weld the shaft that connects to the actuator so that it cant turn. worst comes to worst and you can always make a bracket that holds it shut
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Old 12-14-2006, 12:04 PM   #10
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Yeah i kept the shaft and flapper as one piece, the plan was to just put it back in and weld it.
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Old 12-14-2006, 12:33 PM   #11
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A good welder/fabricator will be able to pre heat the casting up to the appropriate temp to weld the mild steel to it. You just need to find the right guy for the job. If you're going to change it, that seems like the best move for optimum function/performance.
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Old 12-14-2006, 01:23 PM   #12
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I'll call the shop today, maybe they'll have a good solution for me that won't break the bank.
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Old 12-14-2006, 04:05 PM   #13
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I just tacked my flapper down with reg-u-lar old mild steel mig wire. I didn't get it hot enough to do any damage and it's not goin anywhere.
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Old 12-14-2006, 04:33 PM   #14
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I was talking about welding a new wg flange on the bottom of the cast manifold and then plugging the old port at the mild steel flange on the port. With the top mount, he's got lots of room for the wg underneath, along with the plumbing and that'll put it where it belongs.
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Old 12-14-2006, 05:01 PM   #15
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Could you drill and tap the manifold for 1" NPT?

I have an HKS that I have drill and tapped a couple of times, If you don't over tap the threads, when you screw in your pipe it will seal pretty well.

But then you'll have some pipe threads sticking up into your exhaust flow...
And you'll only get one chance to do it right...

You might try if 3/8" or 1/2" NPT. In theory it should flow enough, it would be a lot easier to drill and tap, and then just weld an adaptor to the pipe for your Tial.
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Old 12-14-2006, 05:11 PM   #16
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i think this looks like a good solution if the top of the tial wouldn't rub the heater hoses.



The tapping the manifold solution also seems plausible. 1/2" npt is pretty small, I wouldn't go that low.
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Old 12-14-2006, 05:42 PM   #17
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I agree that 1/2" is pretty small, but still larger than the stock internal... If I was at home I would measure the one on my bench for comparison...
Plus it might be easier to find and use (the poster might only have a Ryobi for all I know
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Old 12-14-2006, 06:59 PM   #18
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Craftsman actually, but I also have a full machine/welding shop available to me. I'm leaving for a month here pretty soon but, i was considering the drill/tap method for a while before I made the thread as well. I might just go that way. Put it all in a vertical mill and go home with it. Won't be for like 2 months though probably.
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