[grebo]

I have a gap in my knowledge that I hope you kindly folks can fill for me.

How does the wastegate know when to open and close? Does the ecu tell it based on revs, throttle position etc, or is there some kind of pressure sensor in the intake system (or both).

I know there's a diddy little solenoid that has something to do with it, but not sure exactly what it does.

Cheers
Gary

 

[Guest]

good question .
My understanding is that the wast gate is set , with a spring/ diagphram " watever " and this is set at a certain pressure , i know i am wrong , but i try .

regards , have fun with ure new car , is it in uk yet ?

 

[grebo]

Spring/diaphram theory sounds possible but then how would the two stage boost work ?

Yep, car is in the uk, just waiting for it to be registered. Hope to get it on Saturday.

 

[Guest]

i'm not honestly sure , all i can say , is that boost starts buliding @ 2500 revs , then hits full tilt at say 4500 , hold on time lol.
all figures aproximate

 

[Sarky_FCUK]

It is to do with the spring in the actuator, you have boost pipes to measure the built up backpressure in the exhaust housing to spin the turbos when the desired pressure is met the flange opens and the boost pressure is vented to continuous volume.

Hope this helps

 

[Guest]

sarky , sorry it dosent help
could you please do one of your very informative , reply's for us

thanks in advance

 

[Guest]

with pictures , or diagrams
please

again thanks in advance

 

[Sarky_FCUK]

not going to be able to do it tonight, but I will put one up over the next day or so for you.

 

[Richard Bell]

The Turbo actuator has a spring in it which has a set amount of resistance to hold the wastegate closed. Then your car is on full chat and under boost the vacum pipe to the actuator is no longer under vacum but under positive pressure from the Turbo. When the pressure is more than the spring is set to it pushes the acuator open which in turn opens the wastegate Thats the basics. You then have to think about the boost solonoid which bleeds pressure away from the acuator to allow more boost that the acuator is set for !!!! (I`m not going into that now though).

Hope that helps.

 

[Guest]

thanks , it all helps . keep up the good work
this solenoid would it be a small thing , with 2 small pipes situated by the tower pasenger side ?

 

[Richard Bell]

Sure would, I bleeds pressure from the actuator and back into the inlet. So you`ll find with out it your Turbo may only boost upto 4psi and the wastegate would open but the Solonoid keeps the actuator feed bellow this too let it boost higher.

 

[grebo]

Thanks Richard. So when someone fits a bleed valve (not that I'm thinking of doing so ) to increase the boost pressure, I take it that goes to the pressure feed to the actuator and just makes the actuator see a lower pressure, so it let's the boost build up a bit higher.

 

[Guest]

Yup thats it. What is a laugh for a few minutes is taking the pipe to the actuator off altogether & running unlimited boost. It`ll only be for a few minutes (max) at the most though