boost controller

[Jaei Sun]

I've always had my MBC hooked up with the boost side coming right off the compressor housing of the turbo (T28), but recently I read on TurboXS's site

When increasing the boost pressure to higher levels (15 psi or higher), you will get more accurate, responsive and stable boost pressure by using a pressure supply line directly from the engine inlet manifold after the throttle body housing instead of the pressure line from the pressure side of the turbo as stated in step 3 above. By supplying the pressure directly from the engine inlet manifold, pressure effects due to air being forced through the connecting pipes and intercooler are eliminated from the operation of the wastegate actuator system. Ensure any previous pressure supply lines after the turbo are appropriately blocked.

What kind of pressure effects??

[scheides]

Originally Posted by Jaei Sun

What kind of pressure effects??

With any gas, temperature and pressure directly affect each other. By changing the temperature, you can change the pressure, and vice versa. Air in the intake manifold should always be the same, unless your intercooler is getting heat soaked. Therefore, your mbc will always have the same pressure for reference when trying to displace the ball/spring combo for a set boost pressure.

When you run the MBC sourced from an inlet pipe before the intercooler, there will different temperatures of air coming out of the turbo and your MBC will theoretically have it's ball/spring displaced as different volumes of air pass through it (since it is a pressure-based switch). This would result in different resulting pressures in the manifold (after the intake charge has passed through the intercooler).

With that being said, a lot of people run their MBC sourced from the turbo outlet w/ little or no variance in resulting boost pressure.

PV=nRT

ref: http://en.wikipedia.org/wiki/Gas_Laws