0
EricF, on 27 June 2009 - 09:28 PM, said:
Good post. That said, the 300/70 19T actuator should be more than sufficient if it's in good shape. Given how much travel these actuator springs need to do, I wonder if they ever start to get tired?
My 19T/manual setup was absolutely dead rock solid with just a bleed type manual boost controller, even to 23-24 psi it would hold the target boost level until redline.
I would try messing with actuator arm preload, less preload should be less spiking. Aside from that, maybe try a new or different actuator. The 300/70 worked perfectly fine for me, but maybe not for others.
As an aside, on my blue car currently (B21FT with nice-flowing head and decent cam), I spike 24-25 psi and fade to 19-21. This is with the angle outlet housing and the wastegate flapper essentially wired shut. With a ported conical housing and the same setup otherwise, the fade was to 16-17 psi by redline. I think now it may be the exhaust limiting it, or it could just be the turbine wheel itself though based on my past experiences with the 19T I'm inclined to try other things before accepting that possibility.
My 19T/manual setup was absolutely dead rock solid with just a bleed type manual boost controller, even to 23-24 psi it would hold the target boost level until redline.
I would try messing with actuator arm preload, less preload should be less spiking. Aside from that, maybe try a new or different actuator. The 300/70 worked perfectly fine for me, but maybe not for others.
As an aside, on my blue car currently (B21FT with nice-flowing head and decent cam), I spike 24-25 psi and fade to 19-21. This is with the angle outlet housing and the wastegate flapper essentially wired shut. With a ported conical housing and the same setup otherwise, the fade was to 16-17 psi by redline. I think now it may be the exhaust limiting it, or it could just be the turbine wheel itself though based on my past experiences with the 19T I'm inclined to try other things before accepting that possibility.
To add to this,
Exhaust was a big reason for my boost fade. There were three factors though, exhaust, boost control and the turbo was dying. I upgraded the actuator to fresh unit off a 16T, put a 3" downpipe on and then rebuilt the turbo. After that, I got rid of the MBC because it wasn't doing me any favors. Boost fade was radically improved. To be honest, I drive like a grandma most of the time, so I don't really notice any at all. When I get on it, it holds like it should. I run a 15g at 17psi and it might fade to 15psi or so in the very high RPMs.
When it first started to fade I went through my IC pipes, tightened the actuator and messed with the MBC settings. I took off a brand new CBV and checked it for leaks. I put more spacers in the CBV and cleaned the CBV mating surfaces. I was scratching my head and checking things twice. Boost fade was still there.
There are dual nipple actuators that are very strong. I think 10psi. You're situation is different than mine in the way that your turbo is moving more air and has higher PSI's too. So you'll need to allow more exhaust and have a stronger actuator. If you're running an MBC or EBC, remember that it's telling the actuator what to do. It can compensate for small issues by adjusting it but it can also create others.
- If I ever go back to them once TT is in place (it is a Mustang Dyno), I'll make sure they run it up to at least ,65K.
But you definitely need those cams if you want a strong top end (which I'm assuming you do?). With just my 15g, it was the fastest stock ecu'd 850 I've ever been in. All I had was a really good stg. 0, 12psi, n/a cams, r manifold and 3" exhaust. After I put the 16t on, it got even better. I'm currently working on a Fiore-style turbozilla right now....so we'll see where/how that goes 
