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Hey all! I am needing some help. I have an LT4 engine that has a turbo setup on it and I am having and i cannot get the car to build boost properly. It has a precision waste gate on it with an 8 PSI spring. It has a off brand Blow Off Valve on it. It seems to not be building enough boost to open the waste gate. I noticed when accelerating the engine the BOV is opening up and i have heard this should not be happening and could be causing my issues. The BOV has a single vacuum port that is ran to the intake manifold. I am new to this setup and any help on what my issue might be or if this is plumbed wrong would be greatly appreciated!
It seems to not be building enough boost to open the waste gate.
If the waste gate was not opening the boost would rise beyond the 8 psi spring setting. It sounds like the opposite is happening, maybe the waste gate is stuck open or opening too soon.
It probably has a vacuum/pressure hose out of place. The manifold pressure is supposed to route to the waste gate in a way that the boost pressure moves the diaphragm (and the valve face attached to it) away from the exhaust stream ahead of the turbo.
The blow off valve is only supposed to work when the manifold pressure spikes due to the closing of the throttle while the turbo is still spinning.
If the waste gate was not opening the boost would rise beyond the 8 psi spring setting. It sounds like the opposite is happening, maybe the waste gate is stuck open or opening too soon.
It probably has a vacuum/pressure hose out of place. The manifold pressure is supposed to route to the waste gate in a way that the boost pressure moves the diaphragm (and the valve face attached to it) away from the exhaust stream ahead of the turbo.
The blow off valve is only supposed to work when the manifold pressure spikes due to the closing of the throttle while the turbo is still spinning.
I’ll check the routing is there a diagram or something you have that I could go off of ? As far as how the vacuum lines need ran from the wastegate to the manifold ? And for the BOV as well ? Thank you in advance for the help !
I don't know what a precision waste gate is; is it a brand? Here is a sketch from the book Maximum Boost that shows the boost control using an external waste gate.
The signal line runs from the outlet of the compressor over to the valve side of the waste gate diaphragm. As the system builds boost the pressure lifts the valve out of the exhaust stream and allows the exhaust pressure to vent past the turbine directly to the exhaust.
Post some pics of your set up if you can, very helpful since most of the turbo set ups are custom and there are lots of ways to make them work.
