Swapping wastegate actuators...

[Mr Ed]

wrong.
there isnt a boost controller in the world(short of one that has a vacuum pump) that could stop the exhaust gas pressure over riding the weak spring.

a solenoid controlled boost controller will generate a small amount of vacuum as the diaphragm tries to open when the solenoid is still shut but as frank stated it still wont be enough to control boost completely

But they just open the vacuum line to atmospheric pressure, no controller actually 'creates vacuum' it just stops the actuator from receiving positive pressure until you want it to. They dont open with atmospheric pressure, they open with boost!

Anyways, as previously said youre better off having a more accurately sized spring. My point was that youre better off having an undersized spring than an oversized spring.

EDIT: Got rid of irrelivant point.

[Mr Ed]

Yes and no. I have a 7psi spring in my actuators, and I had to get an eBoost2 to control boost. The Gizzmo just couldn't cope with the way it ramps up very quickly. I think with a spring closer to the desired pressure, it would've been fine.

So when you say Gizmo, you mean thats some type of manual bleed valve yes?

I think this is just a case of the little opening in a manual bleed valve just wasnt big enough to let all the air out quick enough to stop it getting to the actuator. Eboost must have a bigger opening in its solenoid that the manual valve.

Yes if you had a bigger spring it would be less sensitve and the problem could also have been solved this way too.

[JustCallMeOrlando]

I think he's referring to the older style of electronic controller which worked like a variable bleed. The newer ones all actually get in the path of the wastegate and the reference line and can use their gate pressure setting to stop any wastegate creep.

[JustCallMeOrlando]

So when you say Gizmo, you mean thats some type of manual bleed valve yes?

Nope, the Gizzmo is an electronic boost controller. Incidentally it uses the exact same solenoid as my eBoost2. It was unable to control boost properly on my setup, due to most likely having the "sensitivity" too high. Boost would spike either side of the set point before finally settling down.

[Mr Ed]

Nope, the Gizzmo is an electronic boost controller. Incidentally it uses the exact same solenoid as my eBoost2. It was unable to control boost properly on my setup, due to most likely having the "sensitivity" too high. Boost would spike either side of the set point before finally settling down.

So the Eboost still fixed it? I cant explain that.

Or did you swap the spring as well? Sorry Im at work and my head hurts too much to figure this out.

[hybridaddy]

here is an explaination of what i meant before.

electric boost controllers have a solenoid which remains closed untill the signal is given to open the gate.
so we have a closed line from the solenoid to the front side of the diaphragm.
when the exhaust gas tries to push the gate open it is also creating vacuum in the front of the diaphragm helping it to keep the gate shut,but it can only hold so much before the gas pressure over rides the spring pressure and the small amount of vacuum created

[Mr Ed]

here is an explaination of what i meant before.

electric boost controllers have a solenoid which remains closed untill the signal is given to open the gate.
so we have a closed line from the solenoid to the front side of the diaphragm.
when the exhaust gas tries to push the gate open it is also creating vacuum in the front of the diaphragm helping it to keep the gate shut,but it can only hold so much before the gas pressure over rides the spring pressure and the small amount of vacuum created

Ahh ok, I see.

I havent seen an external wastegate in pieces so Im not 100% sure how they operate. Ive seen an internal wastegate workings and I thought the gas pushed it closed, not open. So is it different for int/ext gates? Are internal gates easier to control?

Of course due purely to them being generally under sized they are still prone to boost spiking.

[hybridaddy]

they are both the same in principal,a valve that is opened by a diaphragm but held back by a spring.
if allowed to the exhaust gas will open the valve by its self,this is what you are trying to control.
a properly calibrated wastegate has a stiff enough spring to withstand the highest pressure the exhaust can throw at it and still not open untill you give it the signal.

an internal gate does not flow aswell as an external gate and because of that it needs to open earlier in order to stop boost spiking.

the external gate can control the boost very quickly due to its larger valve surface area and 360 degree flow path and for that reason can stay shut right up untill the last moment without spiking.

[mullett]

okie kokie, back on topic again Not that I really mind the extra info that's coming out of this...

I made up a plate today to make the CA wastegate fit onto the RB turbo, it's all coming together beautifully. There's plenty of travel (2mm MORE), all I have to do is shorten the arm a little. I'll take some pics of the components for future reference if anyone needs it. Another advantage of this mod is that the new wastegate will use the bolts securing the intake housing, giving much more freedom of rotation...

RM.

[My_ToyMota]

hey sorry to take yer thread but anyone know how much boost stock 1jz gte vaccum actuator holds? i had to use one on my mates vg20 im halfway through mounting the turbo above the gearbox. i had to use this cause its bracket was large enough to mount it on the comp housing when i rotated the housings to face diff directions.

[Mr Ed]

hey sorry to take yer thread but anyone know how much boost stock 1jz gte vaccum actuator holds? i had to use one on my mates vg20 im halfway through mounting the turbo above the gearbox. i had to use this cause its bracket was large enough to mount it on the comp housing when i rotated the housings to face diff directions.

Wateva stock boost is on a 1JZ, stock engine doesnt have a boost controller of any type so the spring rate is set exactly to stock boost. I dont have one so my knowledge is limited, 11psi sounds right but youll have to check it with on of the 1J boys.

EDIT: Did a bit more looking around. Havent been able to find any official specs on it but seems stock boost is about 10psi, some people say 10.5psi.

[YLD-16L]

we have a closed line from the solenoid to the front side of the diaphragm.
when the exhaust gas tries to push the gate open it is also creating vacuum in the front of the diaphragm helping it to keep the gate shut,but it can only hold so much before the gas pressure over rides the spring pressure and the small amount of vacuum created

That all sounds fine but where is the vacuum coming from? Do you run your reference line from the manifold post throttle body? All cars should have the reference for the wastegate actuator taken from the compressor housing or the first section of pipe imediately after the compressor housing

A lot of people would have more stable boost control and less spiking if they kept the line/s from the boost reference point to the wastegate actuator as short as possible

[brett_celicacoupe]

That all sounds fine but where is the vacuum coming from? Do you run your reference line from the manifold post throttle body? All cars should have the reference for the wastegate actuator taken from the compressor housing or the first section of pipe imediately after the compressor housing

A lot of people would have more stable boost control and less spiking if they kept the line/s from the boost reference point to the wastegate actuator as short as possible

i think i know what he means.... picture this;

think of one of those cylindircal push bike pumps that you pull in and out

a hand push bike pump is pushed all the way in and you put your finger on the outlet and then try to pull the pump out....what happens? there is a vacuum created which trys to suck your finger in. in the case of the turbo, it is the wastegate being forced open by the exhaust gas that causes the 'pump' to pull apart.

alternatively, you could put your finger on the barbed fitting on the wastegate actuator and grab the actuator rod and jerk it in and out....the air has to come from somewhere


the larger the diameter of the diaphram and the more the movement of the actuator rod, the more this will happen

[YLD-16L]

i think i know what he means.... picture this;

think of one of those cylindircal puch bike pumps that you pull in and out

a hand push bike pump is pushed all the way in and you put your finger on the outlet and then try to pull the pump out....what happens? there is a vacuum created which trys to suck your finger in. in the case of the turbo, it is the wastegate being forced open by the exhaust gas that causes the 'pump' to pull apart.

Ahhh yes, the small amount of vacuum that will start to form in the sealed section between the solenoid and the wastegate diaphragm as the wastegate is pushed open by the exhaust gasses

Cool, that's all clear in my fuzzy head now

Cheers.