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DIY Turbo Discussion greddy on a 1.8? homebrew kit?

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Old 03-26-2012, 08:30 PM   #1
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Default Overboosting Problems

Hi guys, I just installed a shanghai-s kit along with some 460 injectors and a 3" enthuza exhaust and am having lots of boost creep/overboosting. I have a 5psi actuator but that seems to have zero bearing on my boost. I adjusted it fully open and yet my boost still hit 14 pounds before I let off and it felt like there was lots more on the table. So far from what I've read my only real choices are ewg or getting my iwg ported. Any thoughts??
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Old 03-26-2012, 08:41 PM   #2
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Yes, I am 99% sure it is your wastegate flapper not opening all the way. Take the actuator rod off of the flapper and see if it will open or if it hits the downpipe.

I had the begi-s downpipe and that is what happened to me.

See this thread:
https://www.miataturbo.net/showthrea...ownpipe&page=2
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Old 03-26-2012, 08:42 PM   #3
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-Disconnect the wastegate actuator from the WG flapper, then cycle the flapper through its full range of motion. Videotape that so we can see whether the WG is opening far enough.

-Confirm that your 5psi actuator is actually a 5psi actuator. Hook it up to an air compressor or a bike pump or a hooker's mouth and pressurize it to 5psi. The arm should move at or just before 5psi.

-Disconnect the flapper door and make a run. If you're still getting 14+psi, then you need an EWG or porting, although for some not even the porting is enough.

A non-BEGi bellmouth downpipe (think ARtech makes them? I know ABSURDflow used to, but I don't think Tim is doing downpipes anymore) will also help this issue.

This is not uncommon for Garrett-style internal gates and 3" exhausts.
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Old 03-26-2012, 11:33 PM   #4
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Wow I can't believe I didn't notice that the flapper was hitting. Just barely. I'll grind it down and then go on a drive with it disconnected. Thanks for the quick replies guys. Y'all are awesome
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Old 03-27-2012, 10:34 AM   #5
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Grind the flapper? That sounds like a bad plan...
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Old 03-27-2012, 11:57 AM   #6
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If I wasn't clear I'm sorry. Grinding the top of the downpipe so the flapper can open fully
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Old 03-27-2012, 12:27 PM   #7
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Ah, when people said the flapper hits the downpipe, I always assumed the actual flapper inside hit the inside of the dowpipe. Never understood how Begi would let something like that out into the world. This makes much more sense.
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Old 03-27-2012, 12:30 PM   #8
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Is it possible for you to loosen all the bolts on the DP studs and just move the DP around slightly to get the flapper to open all the way? I know with my chinacharger and Begi DP I had to play with it a bit to get it in a perfect working order.
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Old 03-27-2012, 12:50 PM   #9
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Do this first. Just loosen the bolts and move the DP while testing the WG flapper. I just had to do this after replacing the 2554 with a 2560 recently. No grinding was done.

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Originally Posted by shuiend View Post
Is it possible for you to loosen all the bolts on the DP studs and just move the DP around slightly to get the flapper to open all the way? I know with my chinacharger and Begi DP I had to play with it a bit to get it in a perfect working order.
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Old 03-27-2012, 05:36 PM   #10
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Well I was there trying to get the bottom two bolts off but I have a herniated disk in my back that I'm having surgery on in a week so I couldn't get those bottom bolts off. I just decided to grind the top down but now it opens fully. Doesn't look very good but it'll work! I'll have to take a drive now!
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Old 03-27-2012, 05:40 PM   #11
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Quote:
Originally Posted by skidude View Post
Ah, when people said the flapper hits the downpipe, I always assumed the actual flapper inside hit the inside of the dowpipe. Never understood how Begi would let something like that out into the world. This makes much more sense.
Yea the downpipe had enough adjustment that it should have been fine but I just didn't think about it at all so I wouldn't necessarily blame begi for that.. my
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Old 03-30-2012, 06:19 PM   #12
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Quote:
Originally Posted by cowboys647 View Post
Well I was there trying to get the bottom two bolts off but I have a herniated disk in my back that I'm having surgery on in a week so I couldn't get those bottom bolts off. I just decided to grind the top down but now it opens fully. Doesn't look very good but it'll work! I'll have to take a drive now!
Wow, those herniated disk things can hurt like a ba#tard!
I had a 14mm L5/S1 done in November. But thankfully the recovery is on track. My advice is to walk a lot post op. I wish you all the best and i am sure it will go well.
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