MHI Big 16g actuator pressure

[CleanPalms]

I realize this question has been touched on a couple of times and am familiar with the fact that a non ported flapper only opens around 3/8". But what hasn't been confirmed is at what PSI this turbo is supposed to stop building boost at.

Extreme PSI says: This factory upgrade for the 90-99 DSM cars increases compressor flow by 25+% at 550 CFM at 15 PSI boost. Supports 380 HP. It has a larger 7CM2 turbine housings for reduced back pressure at high RPM. It is a direct replacement for the first generation TD04H and TD05H turbos.

But I'm curious as to if that's what the tests were ran at with some boost control device (like an mbc) or if that was straight jpipe to wga. The reason I asked is because even when I bypass my b&s mbc, I still get infinite boost. I will be applying an air compressor to the wga to see when/if it ever opens today but am curious as to if there is a solid number on what PSI its supposed to "stop building" at.

Everything about my car is in my profile if there is anything else needed, please ask and I will provide. And yes, I'm certain its infinite boost and not creep. Even though I refuse to let it go over 25 psi on my fuel setup.

 

[Steve93Talon]

I realize this question has been touched on a couple of times and am familiar with the fact that a non ported flapper only opens around 3/8". But what hasn't been confirmed is at what PSI this turbo is supposed to stop building boost at.

People just port the area behind the flapper arm so they can open the door farther to port the hole without the flapper in the way. You don't actually gain any flapper travel by doing this with a stock type actuator.

The stock actuator is around 10psi, give or take a bit. If you have 3" exhaust and no wastegate porting or external dump, you'd probably creep to at least 15-17. Try to pressurize your actuator and see if the flapper arm is opening, it could be sticking somewhere or you could have a blown diaphragm inside the actuator. If it opens properly, check the hose to the actuator, make sure it's not split anywhere and is connected to a solid boost source.

If all of that checks out ok, you may just be experiencing a lot of creep. What is your wastegate hole/o2 housing/exhaust configuration?

 

[CleanPalms]

People just port the area behind the flapper arm so they can open the door farther to port the hole without the flapper in the way. You don't actually gain any flapper travel by doing this with a stock type actuator.

The stock actuator is around 10psi, give or take a bit. If you have 3" exhaust and no wastegate porting or external dump, you'd probably creep to at least 15-17. Try to pressurize your actuator and see if the flapper arm is opening, it could be sticking somewhere or you could have a blown diaphragm inside the actuator. If it opens properly, check the hose to the actuator, make sure it's not split anywhere and is connected to a solid boost source.

If all of that checks out ok, you may just be experiencing a lot of creep. What is your wastegate hole/o2 housing/exhaust configuration?

Wastegate Hole - stock as far as I know, the PO gave me an inbox 68HTA when I bought the car so I would assume he planned on upgrading the whole turbo instead of replacing/porting parts on the 16g. But there WAS a PO before him as well who built the car, so I have no idea what he may have done with it. I sent him a couple PMs and a facebook message but he never got back to me. On here he is "97 GSX 97" and I bought the car from his buddy Bill who he had sold it to. Veterans of the site should know it as the Cayenne Red Pearl that got used on Ebay/Craigslist for scams.
O2 Housing - Megan
Exhaust Config - HKS Carbon Ti 3" with Megan Downpipe.

Additionally, I had a really big boost leak when I bought the car a year ago that I just found (as I learned about the car) where the BOV was meeting the Flange. It has a 1g flange with a greddy type-s kockoff bolted on so it didn't sit properly. When I resolved that issue with RTV Sealant and a little grinding this is when the infinite boost started. Originally I couldn't even get over 12PSI.

Edit: You know, I'm not real sure whether or not the Actuator itself is stock or aftermarket, I just noticed on the Extreme PSI website when you buy these, they come WITHOUT the actuator. So I guess I'll head out and look for some Part # maybe? Could be beefier....

 

[LarryJoe]

I'm guessing that if there is a mbc that it was set way higher than 12, and that leak you fixed was only allowing you build to 12.

 

[CleanPalms]

I'm guessing that if there is a mbc that it was set way higher than 12, and that leak you fixed was only allowing you build to 12.

The Ball and Spring MBC by Hallman was set to the very minimum. I did this so I could try and learn everything about the car before changing things that could potentially destroy everything I just purchased. The car when I first purchased it was running at 12psi. However about a month ago my friend showed me how to launch the car (something pretty mild, nowhere near redline) and since then I couldn't build boost at all.

After a boost leak test, I found that the BOV was leaking SO much air it would leak out as fast as I put air into it (I capped the re-circulation port). Air was leaking between the Gasket and the Flange. While I was restoring this issue, I also removed all emissions components, installed an EGR removal plate and a FuelLab AFPR. After placing everything back to together and Boost Leak testing. Everything Held....but I only tested to 20 psi as that's all i wanted to run. I left the MBC at the very minimum and drove it. Realizing I was hitting 20/25psi I immediatley by-passed the MBC thinking the ball was perhaps stuck. Drove with just jpipe to WGA and the same thing occured.

Here we are now.

TLDR: The boost leak I had initially wasn't as bad, but when the car was launched the boost leak became drastically worse.

Edit: You know, I'm not real sure whether or not the Actuator itself is stock or aftermarket, I just noticed on the Extreme PSI website when you buy these, they come WITHOUT the actuator. So I guess I'll head out and look for some Part # maybe? Could be beefier....

Disregard this. Stupid banter. It definitely has the WGA on it that comes with the turbo.