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Boost Control: Boost Control

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Boost Control

02.20

00:00 - If you're driving a turbo charged car the boost pressure is one of the most important parameters you'll want to monitor and control.
00:08 It's essential first and foremost for the performance and reliability of your engine but just as importantly, controlling the boost pressure can have some advantages when it comes to improving the drivability and control of the car.
00:23 The actual boost pressure is usually controlled by a waste gate valve which is a pneumatic valve assembly we'll look at in detail in the next module.
00:32 While there are turbo charges available such as variable area turbine nozzle or turbos with an electronic waste gate.
00:41 The focus of this course will be on the more common pneumatic waste gate system.
00:47 Achieving stable and consistent control over boost pressure sounds simple enough, but in reality, it can be quite a challenging aspect of engine tuning.
00:57 The reason for this is that the actual turbo charger assembly is always operating under changing conditions.
01:05 While atmospheric temperature and pressure would be a pretty obvious aspect here, the actual heat of the exhaust manifold in turbine housing are also constantly changing, and this can present a more subtle change in the boost control.
01:21 The turbo charger is driven by the energy of the exhaust flow entering it and this comprises both the mass flow of the exhaust gas as well as the heat of the gases.
01:31 For this reason, if the exhaust gas is hotter, we tend to find that more energy will be provided to spool the turbo.
01:38 An easy illustration of this would be to perform a dyno run with the turbo charged car, when the exhaust manifold and turbo are relatively cold.
01:47 If we then hold the car in steady state on the dyno, with a little boost pressure, for 30 to 40 seconds and repeat the test, we'll find that the engine will achieve maximum boost earlier in the rev range.
02:00 And, often, make more boost.
02:04 It's aspects like this that make tuning electronic boost control, a little more challenging.