The waste gate is a door to allow exhaust air to bypass the turbine. It is opened and closed to modulate how much exhaust gas flows over the turbine and in turn modulates how fast the turbine spins the compressor which, in turn, controls how much pressure is built up in the manifold in area "A". Too much pressurized air entering the combustion chamber can cause premature detonation as the piston compresses the hot high pressurized air. So-called "detonation" can push the piston backwards against the engine's momentum and destroy it. The waste gate is mechanically opened and closed by the waste gate actuator.
The boost controller modulates the waste gate actuator. The input line to the boost controller can be connected to monitor the pressure at "A" in the manifold or alternately to monitor the pressure at "B" at the outlet of the compressor. The boost controller is set to limit the maximum boost pressure. For a stock ZXT the boost controller's set point is fixed at ~6psi but for an intercooled zxt it is typically set to between 10 and 16psi.(more boost means more power from the engine but also increases the risk of detonation).
The pop-off valve is simply an emergency pressure release device to prevent over-boosted air from entering the combustion chamber. It functions by venting the air to the engine compartment when the pressure rises above the maximum boost threshold. For a stock zxt with boost set at 6psi, the pop-off vents at ~9psi. For an intercooled zxt with the boost controller's maximum boost set to 12psi, the pop-off valve would be set to ~ 14psi. The pop-off valve can protect the engine in the instance when the waste gate or waset gate actuator fails. If this were to happen, boost levels could go well beyond 25psi without a pop-off valve present.
The blow-off valve is opened when the throttle valve is abruptly shut to prevent back-pressure on the compressor.
In normal operation, air flows though the compressor then freely into the engine, thus the pressure on each side of the open throttle valve in "A" and "B" is nearly identical. However, immediately after the TB valve is abruptly closed (foot off the gas pedal), the air flow through the engine is nearly brought to a complete halt at the TB. Exhaust air and self-momentum of the turbo wheels continues to spin the compressor. The compressor then continues to pack air into the now sealed area "B". The packing of air rapidly increases the pressure in "B". This high pressure air in "B" causes backpressure on the compressor and slows it down. (a bad thing for performance and it also causes an unusual strain on the compressor). Since the blow-off valve is monitoring the pressure in "A" it can tell when the pressure in "B" is different from that in "A". If this pressure differential is too high, the blow-off valve will open and allow the high pressure air in "B" to vent back in "C". This equalizes the pressure on each side of the compressor thus it spins freely and does not suffer the back pressure problems.
A common mistake is to vent the blow-off valve into the engine compartment rather than re-circulating to the front of the compressor. By venting the air that was "metered" by the AFM, the air to fuel mixture changes and the engine runs rich.
LoL... I may sound like a dumbass to you, but I was manily giving off my information based of off 280ZXT motors the L28eT.
I figured since in 1983 Nissan made the last of the inline 6 turbo engine.. and in 1984-1989 moved onto the 300ZX, I assumed the turbo's were nearly identical.
I assumed not actually looked into it.
JAMESZ how can you tell me where do I get my crap? Explain to me what in my little post was wrong other than the ranges in the maximum and average PSI put out by the stock turbo?
It is a bad idea to plug the pop off valve like I metioned earlier because the pop off valve protects the engine in the instance when the waste gate or waset gate actuator fails. Now why would you risk that?
Incorrect statements? LoL... i don't get it.... why don't look up what i said in both posts and tell me waht was incorrect other than the numbers in the PSI range of the 300ZX turbo?
:dumbass:
