Have you tried removing the boost pill and running directly, just to see if it "levels" out and doesn't overboost.

 

Be easier putting a piece of pipe between actuator and comp hous, that would prove WG hole is big enough

 

I have a 16g and found that the standard "China" acutator was opening at 0.5 bar , which made it impossible to get more than 1.0 bar out. Then when I found this out I also notice it even leaked presure. That then gave me boost creep. So you need to check that the actuator - pipework holds presure otherwise the system leaks back and the gate closes and causes over boost , that flutters about as the map tries to compensate via the twin port , so no matter how good your mapper is leaks are not linear and are likely to change speeds at different temperatures.

I organised myself a good quality Kinguwa actuator , this has an adjustable spring types , and is a reliable well made bit of kit.

 

Im using A chinese actuator on my genuine MHI turbo, it peaks 1.7 bar and hols 1.45 ish. lots of pre load though!

 

It should not need more than a 3mm preload.

And if you can't bleed of the presure off, then Audibly just about the same time that the rings try to escape past the top of the piston. you'd be amazed how quick it reaches 2.5 or even 3 bar on your dashboard gauge !!

 

It needs as much as it needs! Although I still test my "base" pressure by running a pipe straight from compressor to WG with no boost control connected. Remeber I have quite a large ported WG housing, it needs very little movement to control the boost pressure

 

same here when setting up a car - will start at base pressure/zero WGDC then start increasing until we start homing in on target boost

 

I can see that this makes sense if you only need a minor movement to control boost due to the ported housing, so for yours the point where it actually starts to crack open , has a quick effect to dump excess boost.

The issue with more preload on the cheapy actuator is that the bracket just bends as you pull like a rigger to pull the arm over the pivot /spigot.
It probably even does not stay put once the assembly gets hot.

So Its not a good game bending it back again, and risk mucking up all the work done during mapping. The Kinguawa, has a diaphram that you can replace and with different spring rates you tune the rate of WG opening from the initial crack open to a known pressure for a 5mm travel and that makes mapping subsequent boost control / tail off a little easier to dial in.

 

If you want an Impreza "daily driver" that pulls torque well from low down in Rpm and your target is 300bhp .

Then its simple use the TD04 and work on the exhaust system, with a good map and you should be at 290 , the best I have seen a graph for was just over 300. and It would be nice to see someone here tick off all the boxes to get that and post a graph. In my view still a nice way to make the 2.0 go really well.

I have a TD05 16g, and while its neither spectacularly fast with 340 hp
(& medium turbo lag) nor is it a car to enjoy around town. If those of us with these are honest 2.0 's with the TD05 16G drive like 1.3 Fiestas until you decide to drop a gear mix it up and slip the clutch.

The 2.0 needs more cubic , the turbo design is now archaic , so if you want more torque, just look to the Sti with AVCS / stroke to 2.1 and put a twinscroll in.

Subaru saw this and finaly came up with a comprimise for the 2.0 its called the WRX sti tS sadly only in Japan. Recently reviewed here in Germany by the drivers club www.subaru-drivers-club.de

 

Totally agree with this.
A good mapped TD04 will feel very fast because of absence of lag.

Buddy of mine runs a vf35 @310 hp(5 speed..) i run a Billet 20G. @1 bar (is about 300hp as well)... he walks out on me, turbo comes in, i fly past him... etc we reach 200km/h at the same time at the highway, however his car has soooo much better drivability..

 

Okay, to update on this issue (compressor stall)!

Duncan and his mate took one look at it and diagnosed problem with a finger and thumb.

Know what it was?

 

I've already voiced my opinion

 

Oooh arr lass likes a finger and thumb

What was it? Hole in a boost pipe? Missing restrictor pill?

 

It was something far more sinister... (not)..

The intake pipe was collapsing under boost. Seems the elbow bit was too squidgy! I have proved this theory by relocating the pipe slightly - stretching it so it can't collapse. The stall has virtually gone... I will be replacing this pipe!

 

Fingers.. thumbs.. holes ...

 

Pleased to see you found the problem.

I had heard this happens to a lot of the aftermarket ones ,
what type was it ?

The standard ones have nice ribs in them and don't collapse ,
I read somewhere that they actually flow fairly well for anything
up-to 400hp .

However my old Std part had gone soft / sticky close to the junction to the turbo , & likely to rip if I really tightened the jubilee clip up.

I felt a replacement , was needed so I bought one S/H on here for 40 quid.