Can a wastegate flap be pushed open from the inside directly by boost?
#1
Can a wastegate flap be pushed open from the inside directly by boost?
I'm on the standard actuator spring (probably 7PSI), and with an EBC at 100% duty I'm only getting a max of 12.5PSI.
I read a lot about boost creep on the TD04, so ported my exhaust housing to the wastegate heavily (though did not touch the material that seals with the flap); is it possible that my porting has diverted the gasses so much to the wastegate that the flap is being pushed open from inside and overcoming the actuator spring? Is this a thing?
I read a lot about boost creep on the TD04, so ported my exhaust housing to the wastegate heavily (though did not touch the material that seals with the flap); is it possible that my porting has diverted the gasses so much to the wastegate that the flap is being pushed open from inside and overcoming the actuator spring? Is this a thing?
#3
This is my MAP against RPM. My boost solenoid is at 100% duty at the top of the revs but it still won't make more than 12PSI.
I'm tempted to tie down my wastegate, gently accelerate to 5000rpm, and then floor it to see if I can make more than 12PSI. This will prove I'm experiencing the exhaust gasses pushing directly pushing the flap, will it not?
I'm tempted to tie down my wastegate, gently accelerate to 5000rpm, and then floor it to see if I can make more than 12PSI. This will prove I'm experiencing the exhaust gasses pushing directly pushing the flap, will it not?
Last edited by EddieJT; 08-08-2021 at 01:19 PM.
#7
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Hook it up without EBC, or turn EBC off and see what your waste gate pressure is. That will give a better understanding of what is happening, and what spring you actually have now.
Yes, about 2X waste gate pressure seems good for a typical sized, single port can.
If you do wire your WG closed, have Boost Cut set to 14 psi, as well as being careful. The computer is faster than your foot.
DNM
Yes, about 2X waste gate pressure seems good for a typical sized, single port can.
If you do wire your WG closed, have Boost Cut set to 14 psi, as well as being careful. The computer is faster than your foot.
DNM
#10
Unhook and plug the vacuum line running to the WGA, see what happens.
Have you done a boost leak test?
Short answer is, yes, it can get blow open. But I would be surprised if it was that low. My friend had the greddy td04 and it would run 20+ psi with the vacuum line off and it's waste gate would open at like, 5psi normally.
Have you done a boost leak test?
Short answer is, yes, it can get blow open. But I would be surprised if it was that low. My friend had the greddy td04 and it would run 20+ psi with the vacuum line off and it's waste gate would open at like, 5psi normally.
#11
No boost leaks; I got the system to hold 1bar of pressure for quite a while without any leaks.
Perhaps your friend is experiencing what a normal TD04 will do; I have (regretfully) ported my wastegate channel a lot within the exhaust housing.
Interestingly, I have just been for a drive with the EBC switched off, so just wastegate pressure; it now surges rhythmically as you floor it. In the below plot you can see the boost fluctuating. Does this suggest the wastegate flap is indeed being pushed open by exhaust gasses directly, or is this what happens when you exceed the boost pressure of the wastegate spring?
I switched the EBC back on, and the surging stopped and it pulled as per normal (but still hitting it's 12PSI ceiling despite EBC working at 100%).
Perhaps your friend is experiencing what a normal TD04 will do; I have (regretfully) ported my wastegate channel a lot within the exhaust housing.
Interestingly, I have just been for a drive with the EBC switched off, so just wastegate pressure; it now surges rhythmically as you floor it. In the below plot you can see the boost fluctuating. Does this suggest the wastegate flap is indeed being pushed open by exhaust gasses directly, or is this what happens when you exceed the boost pressure of the wastegate spring?
I switched the EBC back on, and the surging stopped and it pulled as per normal (but still hitting it's 12PSI ceiling despite EBC working at 100%).
Last edited by EddieJT; 08-10-2021 at 03:17 PM.
#13
So I fitted the 13PSI spring and it made no difference.
Then I removed the line to the actuator and tested it with gentle acceleration up to 3500, and then full throttle. It's now hitting the set boost limit (205kpa 15PSI) but tailing off at the top end:
Over 6000rpm plot:
Then I kept the actuator off and tied back wastegate:
You can see it finally holds the boost limit all the way to the 7000rpm, like I've been wanting. So what can we conclude from this? Is this proof the wastegate is being pushed open from the exhaust gases at high RPM?
Then I removed the line to the actuator and tested it with gentle acceleration up to 3500, and then full throttle. It's now hitting the set boost limit (205kpa 15PSI) but tailing off at the top end:
Over 6000rpm plot:
Then I kept the actuator off and tied back wastegate:
You can see it finally holds the boost limit all the way to the 7000rpm, like I've been wanting. So what can we conclude from this? Is this proof the wastegate is being pushed open from the exhaust gases at high RPM?
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