All about the BCS and MBCs

Hi Everyone Right - please be gentle... This is my first technical post and no-doubt I've got something factually wrong, so I thought I'd share my understandings of the BCS and MBCs from my recent experiences and investigations. Doc is attached, and if there are any factual alterations that should be made can you please let me know. All I know is that when I needed the info that I've put in here, it found it difficult to get all in one place! Thanks Will

Hi Will a nice good write up there. Altho i thought the wastegate was on the on the exhaust side of the turbo & inside the MBC the spring & bearing (sometimes a washer) fully blocks the air supply to the actuator, the spring tension determines how much boost it takes to move the bearing & allow the actuator to open you can also get EBC (electric boost controllers) which is basically the same as the standard BCS system but has a dash mounted computer which allows you to control it & set it as you wish

hi will a nice write up there, must have taken some time with the diagrams!! the only thing i would add is that the reason the 850's are so playable is that the ecu is UNABLE to ever read the boost levals that the engine is having to deal with...obviously for the "modder" out there which the learned gentleman the post above me certainly is, this is a clear benefit but there are downsides too most noticably the lack of fueling which will generally be rectified by a remap... the later 70's (etm models) used a BCS which read its own boost, this makes fitting a MBC a No No, but does allow the ecu to react if the boost levals go awol or fueling becomes a problem.... The reason you find such a dramatic difference with the MBC is that the BCS bleeds air through the actuator accross the range of the map, this is totally removed with a MBC Im not sure i would put a MBC in line from the BCS to the actuator, however i am currently running a bleed valve in this position in addition to the rica re-map... cheers jod