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== Manual boost control ==
[[Image:manualboostcontroller.jpg|thumb|220px|A simple manual boost controller. A small screw is located in the top of the aluminum body to adjust bleed rate. This model is placed in the engine bay, however the vacuum line could be extended to allow it to reach into the passenger compartment.]]
A bleed-type manual boost controller is a simple mechanical and [[pneumatics|pneumatic]] control to allow some pressure from the wastegate actuator to escape or bleed out to the [[atmosphere]] or back into the [[intake]] system. This can be as simple as a T-fitting on the boost control line near the actuator with a small bleeder screw. The screw can be turned out to varying degrees to allow air to bleed out of the system, relieving pressure on the wastegate actuator, thus increasing boost levels. These devices are popular due to their negligible cost compared to other devices that may offer the same power increase.
Additionally,A anotherball type& ofspring manualtype boost controllerscontroller useuses athe ballforce andof a spring toacting controlagainst the amountboost ofpressure to control boost. This is installed with one boost signal line coming from the intake somewhere after the turbocharger, and one boost signal line going to the wastegate. A knob changes the force on the spring which in turn dictates how much pressure is on the ball. The tighter the spring, the more boost that is needed to unseat the ball, and allow the boost pressure to reach the wastegate actuator. There is a bleed hole on the boost controller after the ball, to allow the pressurized air that would be trapped between the wastegate actuator and the ball after it is seated again. These type of Manual boost controllers are becoming vastlyvery popular since they do not provide a boost leak, allowing faster spool times and better control than a "bleed type" boost controller.
Generally a manual boost controller will not be accessiblelocated from insidewithin the car, though some are designed to be. An installation that allows access fromcabin insideof the carvehicle (as opposed from inside the enginelengthy compartment)vacuum ispiping morerun complex, asbetween the tubingturbo/wastegate must& becontroller longercan andintroduce aresponse holeissues mustinto bethe drilledsystem. It is possible and beneficial to use two manual boost controllers at different settings with a solenoid to switch between them for two different boost pressure settings. Some factory turbocharged cars have a switch to regulate boost pressure, such as a setting designed for [[Fuel economy in automobiles|fuel economy]] and a setting for performance.
Manual boost controllers cannot be used to set a specific boost level at a given throttle position (& therefore be used to optimise driveability 7 control issues), although a ball-spring type boost controller does allow the boost threshold to be as low as is possible on a given engine configuration, and also keeps turbo spool as fast as is possible as the wastegate remains completely shut until the desired boost pressure is reached, ensuring 100% of the exhaust gases are diverted through the turbocharger exhaust turbine.
Manual boost controllers do not solve partial throttle/full boost, drivability, and response or lag issues. They can be used in conjunction with ''some'' electronic systems.
They can be used in conjunction with ''some'' electronic systems.
== Electronic boost control ==
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