Originally Posted by Stu @ M Developments
Well, basically, your 8psi actuator spring will hold the wastegate shut until the turbine housing pressure reaches or exceeds 8psi
(Theoretical, as its different due to the size of the wastagate penny).
However, with its the actuators signal connection blocked and airtight or with its slight calibrated bleed, 8psi pressure is not enough to operate the 8psi spring due to the depression that is created behind it within the capsule and thus in essence, the spring rating is increased which is of course why you can run far more boost with air injectors in the first place.
Does that make sense?
that matters on wot / or who set the air injectors up.
as some i've seen have 0.8 or 1.2mm jets on the lower body of the air inj's, so any positive boost can escape duein gear changes, and also changes the amount of boost at same air inj duty in the map.
on mine i have no jet now, but the bottom alloy bolt on the air injectors bodie has a slight groove in the thread, so it still releases the positive boost when the air injectors are shut.
Mine are ford motorsport ones. dont know if newer ones differ.
Originally Posted by the original
why can you not have a boost limit in the ecu so that if it sees, say 28 psi, tthen it cuts the spark?
then surely it won't overboost and blow the engine
if your cars runnin over 29.5 psi and mapped for this, and then the air injectors fail, your need a 5 bar map sensor to relieze this. as 3 bar map sensor only reads to 29 - 31 psi (matters on sensor)