external waste gate tuning/hookup.

[OSCS]

Jim the top port will allow pressure from manifold boost or drive pressure to hold the valve closed by applying the pressure on top of the diaphragm. The spring pressure will also hold the valve closed while the top pressure is building. The bottom port is used to control the opening of the valve by allowing boost pressure to be applied to the bottom of the diaphragm if needed. Some do not use the bottom port and just keep it open to atmosphere.

Regulate the top port so the pressure + spring will control when the lower pressure over comes this to crack and fully open the gate.

Example:
Top - Spring pressure force on valve = 10psi and boost on top port is "regulated" to 25psi.

Bottom - It will take 35+ psi to be applied to the bottom of the diaphragm (by manifold boost) or the face of the valve (by drive pressure) to crack the gate.


Drive pressure will also force the valve to open by the nature of the design. If the drive pressure is greater than the boost + spring force on top of the diaphragm, then the valve will open early and you will need a higher pressure spring to offset the premature cracking at a lower than desired boost.

Knowing the drive / charge pressures by data logging will help in setting up the gate or gates. Create predefined settings for fuel, nitrous, daily driving or racing. They will all have different needs and by using waste gates you can be in the sweet spot for all these conditions and keep the turbos from over speeding and staying in the correct area of the map to achieve maximum density.

So say your drive pressure was really high. Would that prematurely open the gate only allowing you to make X amount of boost with the configuration shown? No matter what I set my regulator at it will only make 25lbs

 

[Blowby]

So say your drive pressure was really high. Would that prematurely open the gate only allowing you to make X amount of boost with the configuration shown? No matter what I set my regulator at it will only make 25lbs

Correct!

Example: Spring force on valve 17psi and you can only make 25psi of boost. - As the turbo starts to spool your drive pressure will be rising at or higher than boost pressure. So lets say that as you hit 20psi boost (regulator wide open) and your drive pressure might be 35psi (since you said yours might be high). You are getting close to, if not already cracking the seal because the drive pressures are pushing up on the face of the valve. Now as you keep your foot on the throttle drive pressure continues increasing at a faster rate than boost is increasing so by the time you hit 22, 23, 24 psi the drive pressure is bleeding off a large amount and the boost pressure stabilizes because of the "leak" in "drive" pressure. The waste gate is doing what it was designed to do by controlling the boost pressure by bleeding off drive pressure.

To resolve this you need to add a higher force spring or more air pressure on top of the gate by a external high pressure supply. Or the turbo is not designed for your power, fuel needs. You could also have too large of a gate installed and as the valve starts to crack open it looses too much drive pressure too fast.

 

[OSCS]

Correct!

Example: Spring force on valve 17psi and you can only make 25psi of boost. - As the turbo starts to spool your drive pressure will be rising at or higher than boost pressure. So lets say that as you hit 20psi boost (regulator wide open) and your drive pressure might be 35psi (since you said yours might be high). You are getting close to, if not already cracking the seal because the drive pressures are pushing up on the face of the valve. Now as you keep your foot on the throttle drive pressure continues increasing at a faster rate than boost is increasing so by the time you hit 22, 23, 24 psi the drive pressure is bleeding off a large amount and the boost pressure stabilizes because of the "leak" in "drive" pressure. The waste gate is doing what it was designed to do by controlling the boost pressure by bleeding off drive pressure.

To resolve this you need to add a higher force spring or more air pressure on top of the gate by a external high pressure supply. Or the turbo is not designed for your power, fuel needs. You could also have too large of a gate installed and as the valve starts to crack open it looses too much drive pressure too fast.

Makes perfect sense.. Thank you

 

[OSCS]

Correct!

Example: Spring force on valve 17psi and you can only make 25psi of boost. - As the turbo starts to spool your drive pressure will be rising at or higher than boost pressure. So lets say that as you hit 20psi boost (regulator wide open) and your drive pressure might be 35psi (since you said yours might be high). You are getting close to, if not already cracking the seal because the drive pressures are pushing up on the face of the valve. Now as you keep your foot on the throttle drive pressure continues increasing at a faster rate than boost is increasing so by the time you hit 22, 23, 24 psi the drive pressure is bleeding off a large amount and the boost pressure stabilizes because of the "leak" in "drive" pressure. The waste gate is doing what it was designed to do by controlling the boost pressure by bleeding off drive pressure.

To resolve this you need to add a higher force spring or more air pressure on top of the gate by a external high pressure supply. Or the turbo is not designed for your power, fuel needs. You could also have too large of a gate installed and as the valve starts to crack open it looseTs too much drive pressure too fast.

Un related but I'm having a NASTY boost leak at 25 psi with the gate disconnected.. It will push trough it and still hit 40-45. I've pressurized the system multiple times and can't find it. With the gate disconnected is there anyways the gate Could be leaking? I swear I hear it through the exhaust.. No leaking up pipes or anything. I'm baffled and open to any suggestions. I figured the 25psi gate problem may be related to the 25psi leak somehow.. The leak is LOUD

 

[Blowby]

Un related but I'm having a NASTY boost leak at 25 psi with the gate disconnected.. It will push trough it and still hit 40-45. I've pressurized the system multiple times and can't find it. With the gate disconnected is there anyways the gate Could be leaking? I swear I hear it through the exhaust.. No leaking up pipes or anything. I'm baffled and open to any suggestions. I figured the 25psi gate problem may be related to the 25psi leak somehow.. The leak is LOUD

What brand and size of gate?
External?
How was it disconnected?

If you just removed the boost line then you are now allowing the spring pressure to hold the drive pressure from opening the valve.

 

[OSCS]

Turbo smart 45 or 46 can't remember. Gate is pyshically connected just not plumbed.. External mount

 

[OSCS]

Both ports are open to atmosphere no plumbing what so ever

 

[Blowby]

Turbo smart 45 or 46 can't remember. Gate is pyshically connected just not plumbed.. External mount

Your spring is being overcome by the drive pressure.

 

[JDub]

Great explanation Mike

 

[OSCS]

Your spring is being overcome by the drive pressure.

Well there it is.. I had DI plumb it for me originally.. David was only utilizing the bottom port. Do you think the above configuration will solve the issue?

 

[OSCS]

Great explanation Mike

I agree blowby your a boss!! Thanks alot man you explained it to where even I can understand LOL

 

[strokin'_tatsch]

Well there it is.. I had DI plumb it for me originally.. David was only utilizing the bottom port. Do you think the above configuration will solve the issue?

You have a 25psi spring in your gate?

 

[OSCS]

Yeah LOL it all makes sense to me now! I'm An idiot! Problem will be solved this evening! Thank you all for this elementary lesson

 

[Blowby]

Yeah LOL it all makes sense to me now! I Am learning from the army! Problem will be solved this evening! Thank you all for this elementary lesson

Just put the boost line to the top and add a mechanical regulator. Start with about 10psi coming out of the regulator and then turn it up to the desired boost to keep your charge air cool and dense.

Then when you have time add a second line to the bottom tee'd to the top boost line like in the picture. This eliminates excessive stress on the diaphragm with a semi balanced pressure acting on each side.

 

[OSCS]

This by far the most informative thread for me. Ive been thinking my truck was quick on 25 psi the whole time! Can't wait to get it dialed in

 

[OSCS]

Just put the boost line to the top and add a mechanical regulator. Start with about 10psi coming out of the regulator and then turn it up to the desired boost to keep your charge air cool and dense.

Then when you have time add a second line to the bottom tee'd to the top boost line like in the picture. This eliminates excessive stress on the diaphragm with a semi balanced pressure acting on each side.

So what are the advantages/disadvantages of running a more loose/stiffer spring? Say 25psi vs. 10 psi?

 

[OSCS]

So I plumbed the boost fitting from the y pipe to the top of the gate and with the regulator fully open I am getting the same "leak" but it's at 30-35psi now

 

[Blowby]

So what are the advantages/disadvantages of running a more loose/stiffer spring? Say 25psi vs. 10 psi?

In your case drive pressure. In an electronic controlled solenoid system when high pressure source air is used a lower spring force is best.

You need to know what your offset psi from boost to drive pressure is. Make sure you add additional pressure to this value when selecting a spring force.

Example:
Boost 35psi peak / DP 45psi peak.
Spring force will need to hold maybe 15psi.

Don't just use the rate of the spring to determine the spring force. Apply a regulated pressure to the bottom and find out just how much it can hold and use the actual pressure you come up with.

Example:
Boost 35psi peak / DP 55psi peak. (with 25psi spring force)
Change to a spring force of 15psi and it will bleed off before you ever make 35psi boost.

Drive pressure offset will rise and fall based on the turbo design and wheels used and the fueling in your tune. You might have high DP mid range where we fuel well but as the fuel drops off at higher RPM's the DP will drop and your boost could increase to equal the DP if it's 1:1 at that point.

Let us know how it works out for you.

 

[Blowby]

So I plumbed the boost fitting from the y pipe to the top of the gate and with the regulator fully open I am getting the same "leak" but it's at 30-35psi now

So you are putting 30-35psi on top of the gate + the spring? EGT's?

 

[OSCS]

So you are putting 30-35psi on top of the gate + the spring? EGT's?

Yup , can my DP really be that high? I mean I know it's a .91 but damn