7/27/04 - Manual Boost Controller & Shut-off valve

I've installed an MBC in parallel with my N75 valve so that I can use the MBC to limit boost when I desire. The main purpose will be to limit spikes occuring above the requested boost level which can occur when the turbo's spooling up and the N75 system doesn't respond quick enough to stabilize boost at that level. I have also included a shut-off valve so that I can close off the path to the MBC, so the N75 works just like stock.


mbc_parallel.jpg dsc00753.jpg dsc00767.jpg
 

 

Here's a graph of boost before installing the MBC in parallel. This is a drag-style run, with time as the x-axis showing gears 1-4.  The car's computer is requested about 20psi, but when the turbo spools up, it overshoots the requested value and tries to compensate:

and here's after installing it with it set around 20psi.  Much smoother: