Internal WG, Dual Port Actuator

[Master Chief]

Hi guys.

I have a GT3071R internal WG, 0.86 AR, curently at 20PSI on a S14 SR20DET.
The car was dynoed on a DynaPack at 457hp/380lbf @ hubs, @ 20 psi.

The thing is that i want to boost more - 24 psi would be my goal, and no matter what i tryed - the boost falls back to around 19 Psi.
I had an HKS actuator to the limit, I had an 18psi Garret Actuator, i even had a helper spring attached wich actualy helped hold the boost at 21 psi - but no more.

I dont want to change to an External gate, and still belive i can reach my goal on the internal gate.

I belive the problem is that the Exhaust pressuer is to high and it pushes the Gate open.
A stronger spring actuator helps, but then causes other problems, like not allowing fine tune of the boost, because too high of spring rate.

I recently discovered, there is what is know as a DUAL PORT ACTUATOR.
This works just like an external gate, wich uses two ports.
One to help the spring of the gate hold the gate closed, and the other, to open it when the desired boost level is reached.

The thing is that all the Dual port actuator i see out there, have a very soft spring compared to the single port gates i had (5,10,12 PSI max, as compared to even 18PSI spring on the Garrett actuator).

My theory says that even though the spring rate is low, the fact that on of the ports is used to add pressure to the spring's rate, relative to boost - this would actually solve my problem.

HKS have the highest spring rate dual port actuator i found - 12.8 psi.
I am just a bit tyred of spending money on Actuators, but i really think this my be it.

Anyone with experience on the subject, can give me some input ?

Will i be able to reach my goal - 24 PSI ?

Before anyone says that they do get 24 PSI of an internal gate, think of the power the car makes at 20PSI in my case...

I guess the question is not wheter 24 PSI on an internal gate is possible, but wheter around 500-550 hp is.

Thanks,
Dany.

[TheRealNighthog]

Is this a t2 or T3 based turbo? Large frame T2 turbos have a bad problem with boost control due to the fact that the exhuast is dumping into the same spot when it is exiting. This causes alot of turbulence that you do not want. Honestly I would suggest that you do go external gate. I have seen gains of 40-50 hp at the same boost levels with similar turbos just by switching. If you are dead set on staying internal gate you can try porting your wastegate hole by about 2mm or so. That might give you better flow and a bit more control over your boost settings.

[Master Chief]

Yes, it is a t25 flange, and i did have the Port enlarged at the time.

My problem is defently related to the high exhaust gas pressure, but a stronger actuator, did help, though it had the downside effect, of regulating the boost in the few 1-2 seconds, after each gear change....

Here is where i am wondering if a dual port actuator, might help.

[TheRealNighthog]

I cant give any info on them since I will never run Internal gate again. Seriously, consider external. Are you on the stock manifold or aftermarket?

[Master Chief]

After Market, but low mount.

[SILVIA_KIDs14.5]

consider a divider chamber it will work much better with what you got i had the same prob on my gt28 when going up to or over 14 psi purchased circuit sports down pipe solved a lot of problems so the exhaust gases and waste gate gases were seperated

[Master Chief]

Might try that, though i would imagine the GATE gets pushed open from the inside part of the WG port, when it should actualy stay shut (during building boost).
NO ?

[TheRealNighthog]

Ideally if you stay internal gated then you want to merge the wastegate exhuast smoothly into the exhuast about 15 inches or so from the turbo. This will reduce turbulence.