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A question..
Why does adding a mbc (of any type)increase the low down grunt and increase spool up...?
the wategate actuator is a diaphragm and a spring
boost pressure acts on the diaphragm and when it gets over a pressure (base boost ) the pressure on the spring opens and moves the rod which opens the wastegate and so limits boost
mbc's interferes with this and leaks some air away so fools the actuator by applying a lower pressure to the diaphragm (normal - leakage )
so attaining higher boost pressures
all well and good but in theory it should have no effect when the boost is low
But we all know that it does
Now take into account the apc valve
this is an electronically controlled valve which manages the pressure on the actuator ie an electronic boost controller ..which can leak pressure away from the actuator for more boost but if the ECU detects knock or conditions which could lead to overboost it can switch the pressure on to the actuator,opening the wastegate and so limit boost
So no effect in the low boost area then...
So why does an mbc have such an effect on the low down boost response ?
Supposition....
Does the APC valve allow the wastegate to open at low boost until it senses WOT and shuts it an allows the pressure and the turbo to spool up
if the mbc is interfering with this process then I can understand it but how can the apc valve perform this function ?
The spring in the actuator has still to be overcome and it will keep it closed until its threshold is exceeded
Any Ideas ?
Have I missed something ?
Why does adding a mbc (of any type)increase the low down grunt and increase spool up...?
the wategate actuator is a diaphragm and a spring
boost pressure acts on the diaphragm and when it gets over a pressure (base boost ) the pressure on the spring opens and moves the rod which opens the wastegate and so limits boost
mbc's interferes with this and leaks some air away so fools the actuator by applying a lower pressure to the diaphragm (normal - leakage )
so attaining higher boost pressures
all well and good but in theory it should have no effect when the boost is low
But we all know that it does
Now take into account the apc valve
this is an electronically controlled valve which manages the pressure on the actuator ie an electronic boost controller ..which can leak pressure away from the actuator for more boost but if the ECU detects knock or conditions which could lead to overboost it can switch the pressure on to the actuator,opening the wastegate and so limit boost
So no effect in the low boost area then...
So why does an mbc have such an effect on the low down boost response ?
Supposition....
Does the APC valve allow the wastegate to open at low boost until it senses WOT and shuts it an allows the pressure and the turbo to spool up
if the mbc is interfering with this process then I can understand it but how can the apc valve perform this function ?
The spring in the actuator has still to be overcome and it will keep it closed until its threshold is exceeded
Any Ideas ?
Have I missed something ?