begi shanghai overboosting bad, spacer between turbo and dp? - Miata Turbo Forum - Boost cars, acquire cats.

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Old 05-04-2015, 05:44 PM   #1
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Default begi shanghai overboosting bad, spacer between turbo and dp?

my begi shanghai kit has been overboosting since day one. I am assuming it is because of the flapper banging against the separated gases tube on the downpipe. Doesn't matter how I adjust the waste gate it still creeps to overboost protection on ms (152 kpa, 160 kpa, whatever it is set to). Ive done some research and it seems that some people run a spacer between the turbo and down pipe. I called begi and have been waiting for a call back for a couple weeks. I just need to know where I can potentially buy one from. Is it just a flange or what?
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Old 05-04-2015, 05:53 PM   #2
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Hmm I thought Begi usually ported the wastegates on their chinachargers. Does it look like yours has been ported?
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Old 05-04-2015, 05:57 PM   #3
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Quote:
Originally Posted by Lanceam24 View Post
my begi shanghai kit has been overboosting since day one. I am assuming it is because of the flapper banging against the separated gases tube on the downpipe. Doesn't matter how I adjust the waste gate it still creeps to overboost protection on ms (152 kpa, 160 kpa, whatever it is set to). Ive done some research and it seems that some people run a spacer between the turbo and down pipe. I called begi and have been waiting for a call back for a couple weeks. I just need to know where I can potentially buy one from. Is it just a flange or what?
I'd call them every day.
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Old 05-04-2015, 05:57 PM   #4
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Turn up over boost? Is this with the wastegate wired open?
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Old 05-04-2015, 06:05 PM   #5
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Originally Posted by Lanceam24 View Post
I called begi and have been waiting for a call back for a couple weeks

Good luck with that.
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Old 05-04-2015, 06:09 PM   #6
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Old 05-04-2015, 06:11 PM   #7
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Have you measured your wastegate actuator base pressure?

Also, yes, fix the flapper so it'll open adequately. All the housing porting in the world is useless if the flapper can't open.
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Old 05-04-2015, 06:36 PM   #8
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measured base pressure with a bicycle pump. Starts to move around 5 psi. It barely builds any boost with arm disconnected which I've read is normal, something like 2 psi. I just pulled the bolts joining the turbo to the dp and it seems like the flapper is getting stuck in the tube.
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Old 05-04-2015, 06:44 PM   #9
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pic 1 is it closed, pic 2 is fully open with dp connected, pic 3 is it open with dp disconnected
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Old 05-04-2015, 07:00 PM   #10
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ok so comparing it in person, the way it is now, I don't see how any exhaust gas would escape from the smaller tube. Now, im pretty new to the turbo scene but id imagine its supposed to open at least half way. The flapper would have to be small enough to fit inside of the tube for it to work but its not. It starts to make contact shortly after the flapper starts to move so im thinking some sort of spacer would allow it to open enough. Seems as if I can maybe grind open the down pipe a little bit around the smaller tube but its so thin I might grind through the welds so i'd rather a spacer.
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Old 05-04-2015, 07:02 PM   #11
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With twin outlet flanges I often find that the position is it bolted together in will stop the flapper from opening.

IE, align the downpipe differently and you should find a spot where the flapper opens into the hole.

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Old 05-04-2015, 07:10 PM   #12
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Quote:
Originally Posted by nitrodann View Post
With twin outlet flanges I often find that the position is it bolted together in will stop the flapper from opening.

IE, align the downpipe differently and you should find a spot where the flapper opens into the hole.

Dann
I just tried this and it just wont work, I think the flapper is too big to fit. It almost goes in but the tube tapers down a little bit and it gets stuck. If I try and bolt it together the flapper sticks to the dp
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Old 05-04-2015, 07:16 PM   #13
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Did you loosen the DP from the exhaust and try to rotate it also?
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Old 05-04-2015, 07:54 PM   #14
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Did you loosen the DP from the exhaust and try to rotate it also?

yea same thing
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Old 05-04-2015, 08:03 PM   #15
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Could you just sandwich another flange between the downpipe and housing?

For 200SX 180sx CA18 sr20 T25 GT25 T28 GT28R Turbo Exhaust Downpipe Flange 7254 | eBay
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Old 05-04-2015, 08:13 PM   #16
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Originally Posted by deezums View Post
Could you just sandwich another flange between the downpipe and housing?

For 200SX 180sx CA18 sr20 T25 GT25 T28 GT28R Turbo Exhaust Downpipe Flange 7254 | eBay
that might just be what im looking for. The other posts ive read state that "corky made them a spacer" but it seems to just be another flange. Its already pretty tight so I may have to cut some metal and file a few things down but if it doesn't creep im happy.
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Old 05-04-2015, 08:15 PM   #17
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This is the spacer corky will send you, stop the creep by stopping the exhaust. Physics 101
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Old 05-04-2015, 08:22 PM   #18
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so a flange would be better right. The issue is the flapper cant open all the way due to the opening in the dp being too small. A blank flange like the one you linked looks like it has more space so the flapper can open sufficiently
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Old 05-04-2015, 08:28 PM   #19
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Yeah, assuming it's set up like I think it is a spacer flange would be better than an exhaust restriction.
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Old 05-04-2015, 08:58 PM   #20
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Quote:
Originally Posted by Lanceam24 View Post
It barely builds any boost with arm disconnected which I've read is normal, something like 2 psi.
This tells me that the problem is more likely in the actuator or some binding that is occurring only when the actuator is attached.

You are saying that the DP is preventing opening, yet with the WGA disconnected, that problem goes away.
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