Since I've tightened the wastgate to give me 21-25lbs boost (BstC) I've noticed when I get up to around 15 lbs and slowly let off the gas it starts bucking. The situation I was in was passing on an interstate so I didn't go WOT and I didn't just let off the gas when I was done passing. Should I go back to 17 lbs and see if the problem goes away or has someone else experienced this? Maybe it is an unrelated problem and the timing was just coincidence.
Half throttle bucking
- Thread starter Rick
- Start date
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That sounds like compressor surge. Your turbo is making 21 psi of boost (or what ever the wastegate is set at) but you are trying to regulate it to a lower boost with the throttle blade. This causes the boost to "back up" and an unsteady flow condition at the compressor and over the throttle blade that results in the bucking.
boostedmaxPSI
Hard Member
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- Dec 17, 2001
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- 1,270
Would a BOV help resolve this?
Anyone come up with a good location to mount a BOV.
Thanks
Anyone come up with a good location to mount a BOV.
Thanks
part throttle surge
Part throttle surge is controlled by having your base boost below the surge point and having your tps trigger setting above the surge point.
Do you mean that you have 21 psi with the BstC set all the way CCW? If so this is the problem. Try running more restriction in the wastegate Y hose, or dual solenoids. You need to get the base boost below the surge point.
Raising the TPS trig setting helps also, but the base boost setting is most important for surge.
BOV's don't usually fix this.
Bob
Part throttle surge is controlled by having your base boost below the surge point and having your tps trigger setting above the surge point.
Do you mean that you have 21 psi with the BstC set all the way CCW? If so this is the problem. Try running more restriction in the wastegate Y hose, or dual solenoids. You need to get the base boost below the surge point.
Raising the TPS trig setting helps also, but the base boost setting is most important for surge.
BOV's don't usually fix this.
Bob
T
tracer
Guest
I run an external wastegate and have the same problem. Pardon my ingnorance, but what is base boost? Heard of bass boost
but not base boost
. I only have one way to set my boost that I know of.
but not base boost . I only have one way to set my boost that I know of.That is the base boost on their aftermarket electronic boost controller: BstC.
The following is a very simplified explanation of how it might work:
If a wastegate solenoid is wide open, no boost is used to assist opening the wastegate so it stays closed, and boost increases until something breaks.
If a wastegate solenoid is closed, The full boost level is routed to the wastegate actuator and it will open. This would be the "base boost"
If a wastegate solenoid is electronically cycled on and off, only some of the boost gets to the wastegate actuator, so the boost goes to a level higher than it would if the solenoid was fully closed, but not to the level of fully open solenoid.
The idea of a "TPS trigger" is unless the boost controller sees Wide Open Throttle, it won't allow the boost to go above the base boost and into the "surge zone". The boost controller effectively does with the wastegate what the driver is trying to do with the throttle (accellerate at part throttle). As mentioned above, using the throttle to regulate boost can result in surge.
The following is a very simplified explanation of how it might work:
If a wastegate solenoid is wide open, no boost is used to assist opening the wastegate so it stays closed, and boost increases until something breaks.
If a wastegate solenoid is closed, The full boost level is routed to the wastegate actuator and it will open. This would be the "base boost"
If a wastegate solenoid is electronically cycled on and off, only some of the boost gets to the wastegate actuator, so the boost goes to a level higher than it would if the solenoid was fully closed, but not to the level of fully open solenoid.
The idea of a "TPS trigger" is unless the boost controller sees Wide Open Throttle, it won't allow the boost to go above the base boost and into the "surge zone". The boost controller effectively does with the wastegate what the driver is trying to do with the throttle (accellerate at part throttle). As mentioned above, using the throttle to regulate boost can result in surge.
T
tracer
Guest
Thanks, UNGN. I think I git it. I guess this isn't possible to control with an external gate?
T
tracer
Guest
Thanks. Will investigate.
