Boost fooler elbows

[WarWagon]

Do you have enough fuel to generate boost? With the fuel system issues you may be starving for fuel and the Waste Gate may not be opening at all.

 

[schiker]

An easy test would be plug the boost line from the compressor side and leave the "can" open to see what boost you would make with just a turbo master type set up (spring held closed wastegate).

Can someone explain the "can" assisted wastegate spring to make sure I understand 100%. I think I have it a spring in the "can" holds the wastegate closed. Backpressure alone can open it but boost can make it easier to open by pushing against the spring with a diaphragm/piston mechanism .

During spool up high exhaust manifold pre turbine pressure spikes but wastegate stays closed until boost builds and it helps the the waste gate open such that the engine won't ever see spike intake pressure over X amount of boost pressure. But drive pressure can be higher than what is needed to build X boost (before it reaches X boost).

 

[Husker6.5]

Took the words right out of my mouth, @WarWagon ! If you are running stock/near stock fueling levels you will not produce enough exhaust energy to drive the turbine faster, which in turn spins the compressor faster, which crams more air into the intake which equals more boost (simplified explanation).

 

[schiker]

If my understanding is correct think about this.....

OE the Waste gate is held shut by spring with say 30?lbs of force. Drive pressure is 20 psi = say 25? lbs force on waste gate spring it stays closed until the turbo spools then the "can" sees 15 psi boost piston exerts another 20? lbs force on spring via diaphragm plus the drive force on waste gate it opens the waste gate.

So unless The regulated can pressure is wasted away upon returning to idle its going to revert to a turbo master.

I envision this happening. Just a regulator inline and if the "can" is air tight and it gets regulated to say 10 psi it should hold 10 psi and keep 15? lbs of force on spring holding against the spring reducing the drive force to open the wastegate to same as a 15 lb spring only.

 

[schiker]

You would have to put a check valve in parallel with regulator to allow pressure to come back out of "can" but not push into "can" that would bleed it back to low psi of "can" so it returned to offset spooling turbo-master.

 

[Husker6.5]

With a boost-regulated wastegate, the spring in the can (or on the actuator rod) keeps the wastegate pushed shut against the exhaust drive pressure. The diaphram in the can pushes against the the spring and as the manifold pressure becomes great enough to overcome the spring's pressure, begins to open the wastegate and dump drive pressure which then reduces boost. On my old '84 Subaru Turbo 4x4 wagon the turbo had a boost-regulated wastegate that was set for 7-8 psi of boost. On the advice of a friend who was a Subaru-trained mechanic at the local dealership who told me that they would run them at 20-22 psi all day long at the school without any ill effects, he told me to go to the hardware store, find a spring with hooks on each end and about 18-20 lbs tension, modify if neccessary for length, then hook one end through the canister shaft hole that the wastegate crank arm attached through and then stretch the spring and hook the other end to the back of the canister to put more pressure against the diaphragm and thus make the wastegate open at higher intake boost pressure. Using a restrictor in the manifold boost line to the canister will only delay wastegate opening a few seconds until pressure against the diaphragm builds enough to overcome the spring and push open the wastegate (like when punching it coming out of a corner and you don't want power to fall off).

If you can't get over 10 psi of boost with your HX40xx it is one of two things. Either you are not fueling enough to build enough drive pressure to attain 20+psi of boost, or the spring that PUSHES the wastegate shut is too weak to hold until 20 psi manifold pressure is built against the diaphragm to pull the wastegate open against it, so it opens early at lower psi so you don't attain over 10psi intake manifold pressure. Remember, a boost actuated wastegate works backwards to how the GMx's wastegates (mechanical or vacuum) work. GMx wastegates PULL the wastegate shut and either drive pressure overcomes the mechanical spring pull or the vacuum pump's pull (why the max boost on 94+ GMx equipped is 15psi, it is the 15 psi of vacuum pulled by the pump, boost is controlled by the solenoid bleeding off vacuum to the actuator that pulls the wastegate valve shut, which allows it to open and bypass the turbine, lowering boost).