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?

Hmm I thought Begi usually ported the wastegates on their chinachargers. Does it look like yours has been ported?

I'd call them every day.

Turn up over boost? Is this with the wastegate wired open?

:laugh:
Good luck with that.

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.

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.

http://i276.photobucket.com/albums/k...ps6481fxy7.jpg

http://i276.photobucket.com/albums/k...psawv2mjpp.jpg

http://i276.photobucket.com/albums/k...psrbuqqg2d.jpg

pic 1 is it closed, pic 2 is fully open with dp connected, pic 3 is it open with dp disconnected

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.

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

Did you loosen the DP from the exhaust and try to rotate it also?

yea same thing

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.

https://lh5.googleusercontent.com/Y6..._W4=w1886-h849

This is the spacer corky will send you, stop the creep by stopping the exhaust. Physics 101

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

Yeah, assuming it's set up like I think it is a spacer flange would be better than an exhaust restriction.

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.

I went ahead and got a 1/2" flange. If that doesn't work I'll tinker with it further. I think I need to make a build thread soon to log my progress

^this

If it only makes 2psi with the actuator disconnected then the problem isn't the flapper opening. FWIW, my chinacharger was rated for 6-7psi but went to 9-10 out of the box. I got a 3psi actuator and it went to 6psi without a boost controller. You need a lower pressure actuator if you are going to run wimpy pressure.

You need to listen to what David is saying before adding a crappy band aid that will add more failure points and potential leaks to your exhaust stream.

If you're not creeping with it disconnected, then this "spacer" is not the solution you're looking for.

You're overboost is set to 8.7 psi....You have a 6psi wastegate, and 2psi of boost creep. TURN UP OVERBOOST. Your problem will be solved.

Or get a lower pressure wastegate, but thats money.

he THINKS he has a 6psi wastegate. with begi, the chances of parts being the right ones are like 1 in 10000. so that may or may not be the problem. just cause its cutting out at 8.7 doesn't mean it won't go all the way to like 15. I think a log would probably show us more than OP is describing anyway

I'll turn the over boost up and see how that works. This mainly worried me since I was running the kit just how it came (non intercooled). I was only trying to run what they advertise which is 6-7psi. I recently installed my ic so I'll turn it up and see how that works.

Wire wastegate open and see what happens.

Also, for the love of god stop just telling us numbers and post a log.

THANK YOU.


MT.net on point today.



:brain:



turn off overboost, and post the log to redline.

Please call me at home: 830-885-2144 I should be able to help. You are also welcome to use email: cbbell@gvtc.com..... It may require more than one try.

I'll be home for another three weeks trying to heal up some neck surgery and the boredom is such a killer I've even resorted to looking at this forum.

Your call would be a nice relief,

corky

ok, bolted everything back up.

first, wired wg flapper open. Logged a quick run and max kpa was 106...

then, attached wg back to flapper, set overboost to 250 and did another quick run. Max kpa was 155 (didn't take it quite to redline, but I never really do anyway).

now, the rod is adjustable on the actuator and I just barely screwed it in. I will go out in the morning and turn the threaded adjuster to make the rod shorter and see what that does.

seems to be fine now, maybe nitrodann was right and I just had to unbolt it and reposition it. Anyway check out the logs and tell me what you think because im a noob hah

Hard to tell what is going on without a working TPS signal on the graph, are you not going WOT until after 3500 RPM or are you WOT from low RPM and just making zero boost until you get over 3500 RPM? Can you get some logs where you go WOT from idle to redline in 3rd (or if road conditions allow 4th)? That will tell us spool, creep, max boost etc.

Keith

not going wot until around 3500 or so, ill try again starting from idle

Just to chime in with a similar situation, my shanghai downpipe prevents the wastegate from opening more than 20-30 degrees. I will test it this week with the actuator disconnected but I had the EBC set to 100 kpa and was getting full boost at ~12psi with creep up to ~14 at higher RPM. Even if it isn't the problem, a spacer would make me feel better from a fluid dynamics perspective and it looks like I have the clearance for it behind the turbo.

https://www.miataturbo.net/attachmen...ine=1431439326

https://www.miataturbo.net/attachmen...ine=1431439326

A spacer would not make me feel better becuase it's a janky band aid solution while adding another potential failure point. See if you can re-adjust like OP

I was thinking if the spacer was steel I could just weld it to the DP flange and take out that failure point but I'll take your advice and pursue the cheap advice you guys have posted already :loser:

I see. Well I guess if you welded it, that might actually be ok

I wish I still had my setup to show the crack that is the T3 outlet.

I'm just happy to have a cast manifold now instead of the swiss-cheese fake-SS ebay manifold that came with the car...

I wish you still had your setup for lots of reasons. King of MiataTurbo should have a TurboMiata. [or a bicycle, of course]

I have a subaru, so it's okay.

I have more motivation now to get the boost creep under control since I did some reading on compressor surge...Now I know what the "shoosh shoosh shoosh" noise is when at high rpm WOT...

not surge.

I kinda readjusted mine when I tightened it back on. I tightened the bottom 2 nuts first. I hate dealing with these manifold to engine and turbo to downpipe nuts because they are so hard to get to. I had to cut some wrenches in half to be able to torque them