another overboosting thread
 

I did read through what I could find about this problem, but still not entirely sure how to approach this.

In brief: new install of Shanghai kit with separated gas downpipe (the longer variant). With the actuator rod extended so that you can attach it to the wastegate without pulling on it, I cannot go above 5,000 rpm. By then, I am making 13-15 psi (stock engine, so I lift off the throttle).

The wastegate moves fine, no mechanical interference with the downpipe or anything (about 75-80 degrees). I did a pull with the rod disconnected. It starts making boost at about 5,000 and when I hit the redline is at 7 psi...

On the exhaust side, I have no cat and then 3 inch all the way back. It was suggested to me to put a restrictor plate in the exhaust, but this is not attractive to me, even if it works, because it kind of defeats the purpose.

Open to suggestions.
thanks

sure you have the right wastegate actuator?

I have a garrett 6psi actuator the pn on its side is 430099-0018

the actuator is what came with the chinese turbo. it is straight not bent. the real problem, unless i am mistaken, is that with the actuator disconnected, i am still building boost, which means the wastegate and the separated gases downpipe flows insufficiently. gases go through path of least resistance and at high rpms, looks like some gases find it easier through the turbine than through the completely open wastegate

You want some tension on the WG. If yours is adjustable, give it a couple of turns so that you have to pull just a little bit to get it over the flapper.

Secondly, you need to port the exhaust housing.

You will make boost even with the wastegate disconnected.
The fact that you didn't overshoot the 7psi with it disconnected suggests that you have the wrong actuator though.

yes it is adjustable. i like to put tension on it because it builds boost nicer, but it has an even more pronounced tendency to overboost. the question is, since this is a new system, why would i have to take everything off and port the exhaust housing?

18psi, I wish you are right, much easier to fix than taking off the dp and port. i have the actuator and can that came with the new system, shabghai turbo. what other can should i try?

^^This.
The problem isn't the pressure at which your can is opening, it is the throw of the can being too short. If you strapped a gopro down there with a flashlight and did a pull, you would see your wastegate only opening a crack with the actuator can that is on there. Find a can that will articulate the flapper all the way open and you will fix the issue.

the spring in there is just too stiff.
they are all rated at a certain psi
I bet they shipped yours with a 15psi spring or something like that
meaning even if you loosen the rod and even if it has full travel it will still hit the target the spring in it is set for

only solution I see at this point is contacting begi for a replacement wga or buying another one yourself

churbo + long separated gas DP.....and boost creep, im not surprised one bit. I had same issue with my 2560 with ported WG. I hit about 11 or 12 psi I think with WG disconnected lol, so yours isnt as bad as mine was, at least. Your best option is to port the wastegate (unless begi already did that), usually those churbos have ridiculously small WG ports. or try to get a less stiff WGA (if possible). and you dont want preload on the wastegate arm if you're already getting too much boost

Actually no, you do want some preload or it will spool slower.

What is this kit "supposed to" hit btw?
7psi? or 5psi?

10, I was told.

With a larger exhaust you will probably always struggle with overboost because you have such a tiny wastegate port.

port is not the problem.

You want a 5 or 7 psi wastegate can that can open far.

where can i get one? i would actually want a 10 psi can that does not overboost...

you dont want to run on wastegate only. trust me.
you want something a little under your target then slap on a mbc or bcs to achieve the rest. the spool and power delivery is night and day.

as for sourcing a replacement can, you got the kit from begi I'd start there.

You need to have your downpipe fixed. The long tubes separated gases downpipe uses pretty small tubing for the wastegate size. Have a local fabricator chop off the long piece, add short tube from the wastegate using 1.5 inch tube, and patch the hole at the bottom. I did this for MartinezA92 and it fixed his boost creep problems. I am pretty sure artech has done this on several setups as well.

This is accurate. I was there.

Have you seen some of these churbo wg ports? On my churbo, the wg port was so small I couldn't fit my pinky through it. Sometimes even other parts of the turbine housing have to be ground down to allow full wga actuation. I have witnessed a lack of boost control because the wg port was too small and the subsequent dremel work solving the problem on Godspeed's T28. With a churbo, I would always recommend this as a first step.

Ok, FOR THE LAST TIME (since no one seems to know how to read today):

OP said he disconnected the wga and the car made 7psi. Which means if the wastegate was actually opened properly with a properly rated can (7psi instead of 15 or whatever it is) then IT WOULD NOT OVERBOOST.


Am I not getting something?
Please explain to me how porting the wg is going to help him if he has a 15psi wga. Please.

wga disconnected would mean wastegate has zero influence on the outcome... ie he would get 7 psi if he removed wga completely or was running 1,000 psi actuator.

iirc guys with proper hardware setups would see like, 2 psi or something with wga disconnected- to me theres obvious hardware issue here. again, i would try porting wg first, and/or get downpipe changed so wastegate gasses have a shorter tube to flow thru before being reunited. i had this exact same issue on v1 of my setup.