Page 54 of the FSM Turbo & fuel control chapter. It covers this system, but it does not explain its use, or what it does?

Can anyone please enlighten me on this part of the turbo system.

And particularly the switching acuator.

Thank You.

 

The reason i ask is because my turbo no longer has one. Is this okay?

Help!

 

It's fine, actually considered a mod.
I dunno what is was for, I have a S5 TII.

 

Okay here is what i am talking about ... what is the item that is circled & what does the system do?

 

Look inside a series 4 exhaust manifold. There is a flapper door that blocks off one runner of the turbine housing at a low rpm to spool the turbo faster. The switching actuator is what moves it via one of the solenoids on the vacuum rack. The item you circled is the switching actuator.

The S5 manifold is divided and doesn't use it.

 

so it is a good or a bad thing that i am no longer using this? I sent my turbo away to be upgraded & they took that part off and blocked off the hole where it attached. I was just wondering what the effect of this is?

thx

 

Good thing. It's a common mod to remove it.

http://fc3s-pro.com/TECH/HOWTO/howto.html
Second how-to from the bottom.

 

That's the twin-scroll turbo system. The turbo's exhaust housing has two seperate exhaust paths leading to the turbine. By blocking one of those paths off at low rpm when exhaust flow is very low, the gas velocity is increased, applying a higher force on the turbine and causing it to accelerate quicker. This brings boost in quicker and earlier. Above 2700rpm this flap opens and the exhaust gases can flow through both passages.
While this system sounds like a good idea (I think it is), Mazda obviously didn't think so, because the redesigned 89-91 turbo didn't use it.

 

Ahh, right on. I figured it was nothing bad. I just hate removing things I don't understand. BTW the turbo is a stage 3 from BNR.
· 800-900 CFM compressor wheel
· 15 degree clipped turbine wheel
· T04B compressor housing and back plate
· Dynamic thrust collar
· Ported turbine housing entrance (if not using the switching actuator in the exhaust manifold)
· Modified thrust bearing
· Standard external wastegate flange added to turbine housing (external wastegate is additional)

I just got it back today. I can post some really nice pics of it when I get home from work if anyone is interested. Thanks for the piece of mind guys.