Overview of boostcontrol
- Configuration: GenBoard/Manual/Config/BoostControl
- Testing: GenBoard/Manual/Testing/BoostControl
Typical Pneumatic connections
- For both installs, activating the solenoid raises resulting boost. We need to control PWM-duty to get to boost target. Raised duty = raised pressure.
- An install where raised solenoid duty is needed to (open wastegate and) lower boost is just dangerous. Firmware supports it, of course, but avoid it.
- For an unpowered solenoid, the wastegate should open with relatively low boost.
- therefore solenoid is usually
- Since most often a 3-way valve is used, words like "opened" and "closed" can be misleading (even if 1-nipple left open to athmosphere). Avoid them. Prefer the words "powered" (or raised duty) solenoid or "unpowered" (or lowered duty)
Boost control system layout:
Primary system for internal wastgate:
- adjustable leak valve between the turbo compressor housing (or after IC to compensate for pressure drop over IC.) and node A
- Bottom chamber of wastegate connected to node A
- Solenoid from node A that in it's rest position is blocked and in it's activated position is open to atmosphere
Primary system for external wastgate:
- Wastegate bottom chamber connected to compressor housing (or after intercooler to compensate for pressure drop over intercooler)
- Solenoid from the top chamber of the wastegate, switched to either atmosphere (rest state) or directly to compressor housing. Or to bottom chamber if you are lazy and don't want long pressure lines and don't plan on ever using the extended range system below.
Improved spoolup and range for external wastegate:
- Primary system for internal wastegate connected to the bottom chamber.
- Primary system for external wastegate connected to the top chamber.
The systems are sequenced, first pressure is applied to the top chamber but if that is not enough (remember EBP pushing on the wastegate valve) the boost control working on the lower chamber will start to bleed off boost. In addition to this the system acting on the bottom chamber is always bleeding off as much boost as possible until the system is getting over the adjustable 'spoolup' threshold.
Note that the atmosphere connection can be replaced with a vacuum connection. A vacuum reservoir will NOT work, it has to be a fairly high capacity vacuum pump. (If a zero break pressure check valve is found and used (never seen one) to atmosphere a vaccum reservoir can be used.)
-Jörgen
Audi external wastegate example - under investigation, no final word on this yet; Actually, text below might be bad ! Please review
Connection
- big pipe on the bottom chamber (closest to the valve) connected directly to the compressor (or after IC)
- small nipple on the top chamber connected to the compressor with a solenoid valve in series (I doubt that this is good).
Is this (trying to be) similar as the "boostvalveexternal" example connection ?
Operation - must be verified against the connection
- When the solenoid is powered (routing pressure to the top chamber) the pressure in both chambers should be equal and then it's just the spring acting on the WG valve, and the stock spring should be able to hold the valve completely shut so boost can build up as fast as possible
- to open the waste the (unpowered) solenoid vents the top chamber to atmosphere, and the wastegate would act as a regular WG.
- solenoid is PWM-ed to keep boost at configured level.
See also
- GenBoard/Manual/Config/BoostControl - config variables
- GenBoard/Manual
- GenBoard/Manual/Config
- GenBoard/Manual/PneumaticTube
- InTake/VariableIntake (same type of small solenoid air valve)
- BoostController is the old, developer and brainstorming page