How does the stock waste gate solenoid work?
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bmackinnon
Active Member
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- Feb 24, 2005
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Ok I am still a bit confused.
As I seem to understand, when boost is created it causes the waste gate actuator to open the puck to bypass exhaust gasses to reduce turbine spin.
I am on the right track correct?
So was the solenoid somehow tied into the line that connects to the actuator...??
salvageV6
Daily Driver
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- May 25, 2001
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If you blocked the solenoid line in the Y you would get boost approximately equal to your spring pressure in the actuator.
The Y goes from the compressor to the actuator with a fixed sized orifice in it, and the off center Y part goes to the solenoid to bleed air.
As you bleed off boost with a higher pulsed PWM DC voltage into the solenoid the more air is bled off causing the boost level to rise since there's less air pressure to work the arm.
The stock system can only cause an increase in boost approximately equal to 6 psi. or so of added boost to whatever the stock spring pressure is at stock arm length ie. a non-adjustable arm. PWM pulse width and avg. dc voltage is controlled by the chip in use.
It's a simple system sort of,
that most people have a hard time understanding, who then move on to aftermarket systems and external gates that they also have a hard time understanding and using. 
Aftermarket products add to the mix of issues to understand, for both the stock type systems, and the aftermarket control ones.
I am sure there's a lot more to add but I'm no expert on all the intricacies of all the valves, boost controllers, wastegate pucks, turbo exhaust housing hole sizes etc. that people may use out there.
The Y goes from the compressor to the actuator with a fixed sized orifice in it, and the off center Y part goes to the solenoid to bleed air.
As you bleed off boost with a higher pulsed PWM DC voltage into the solenoid the more air is bled off causing the boost level to rise since there's less air pressure to work the arm.
The stock system can only cause an increase in boost approximately equal to 6 psi. or so of added boost to whatever the stock spring pressure is at stock arm length ie. a non-adjustable arm. PWM pulse width and avg. dc voltage is controlled by the chip in use.
It's a simple system sort of,
that most people have a hard time understanding, who then move on to aftermarket systems and external gates that they also have a hard time understanding and using. Aftermarket products add to the mix of issues to understand, for both the stock type systems, and the aftermarket control ones.
I am sure there's a lot more to add but I'm no expert on all the intricacies of all the valves, boost controllers, wastegate pucks, turbo exhaust housing hole sizes etc. that people may use out there.
mikestertwo
Well-Known Member
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- Sep 13, 2006
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- 5,249
At idle the wastegate puck is closed. All the exhaust gases are going through the turbine which is spinning the compressor, just not fast enough to build any boost. You don't have enough exhaust velocity to build boost at idle.The puck stays closed until you build enough boost pressure to where the puck starts to open controlling the boost.
So is it proportional?
Does the wastegate open asyou build boost and is fully open at WOT?
I guess this is another one of those magical backwards issues that I may never understand.
Yes it opens as you build boost.
Thats why with the adjustable waste gate arms when you make the arm shorther by screwing it in, the puck opens at the same time but not as wide allowing you to build more boost.
Conversely lengthening the arm allows it to open wider to allow more exhaust to get bypassed, instead of turning the turbine wheel; which builds less boost.
I suppose this is why I hear of people "porting" the wastegate puck hole to allow more control of boost creep with a stock style actuator?
And those with the external gate can control the creep better?
(I just have to understand how)
And therefore have an even ammount of boost when you change gears instead of the boose walking all over when the trani shifts (like mine does)?
And those with the external gate can control the creep better?
(I just have to understand how)
And therefore have an even ammount of boost when you change gears instead of the boose walking all over when the trani shifts (like mine does)?
Yep, and then there were the individuals who had the need for larger pucks because their stock one didnt cover the hole fully, hindering their ability to build boost. (you dont hear about that issue much anymore).
I havent had a external gate but I understand it works under the same premise as the adjustable fuel pressure regulators we have.
I have been giving an external gate some consideration.
Now I am thinking about it even more now.
I need to do some more research.
Thanks for the info!
Headed this way anytime soon?
I'm confused. How would porting the hole help with this? Does it allow the puck to fit in the hole better or something?
Just wondering....and learning.
mikestertwo
Well-Known Member
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I'm confused. How would porting the hole help with this? Does it allow the puck to fit in the hole better or something?
Just wondering....and learning.
It allows the wastegate to bypass more of the exhaust gasses for the same amount of opening to help control the boost.
Just found out, can't make it.
Got my buddy coming down for a fun filled weekend of home remodeling!
I hate it, but it has to be done.
No biggie, once it's done the GN is going under the knife!
This thread has helped me realize what is going on with the boost levels I am experiencing. I'm thinking I want that external gate now....
Thats cool you have to care of the home first.
As far as the external gate thats usually seen more on strictly track cars; the stock configuration with THDP works well-- yours just may need some sorting out. The external gate is going to require some extra fabbing from the gate to the DP.
To add to that...if the hole is too small at WOT and your running for example 18 PSI, the boost will "creep" up and up because not enough exaust gas is getting bypasses so it is spinning up the turbine.
Enlarging the hole fixes it but should be done in small increments-- too big of a hole and it wont build enough boost, so there is a balance to achieve.
