CT26 wastegate?

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CT26 wastegate?

Postby theUNYTEDone » Mon Jan 30, 2006 2:23 am

i am aware that 3sgte owners' turbos have an internal wastegate. can these be replaced? my mechanic checked out my motor and says my wastegate is rattling, which could be a boost leak, in turn hindering performance. while there is this scenario, i also viewed a thread about clocking down one's turbo. there are pics and everything, but those all looked to be an EXternal wastegate. could someone free up some info and distinguish the two? as well as let me know whether or not mine's needs to be replaced...thanks much!
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Postby 88Allheeze » Mon Jan 30, 2006 3:20 am

I got pics of my st165 with a clocked down supra turbo and remounted wastegate acutator if ur interested.
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Postby Stubble » Mon Jan 30, 2006 3:24 am

The CT26 has an internal wastegate and an external wastegate actuator.
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Postby theUNYTEDone » Mon Jan 30, 2006 3:43 am

pics, anyone? will i need to get a new one if it "rattles"?
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Postby Stubble » Mon Jan 30, 2006 4:59 am

It should only rattle if the wastegate actuator spring is loose and not working. The wastegate itself is just a flapper door inside the turbine housing that is held closed by the diaphragm spring in the wastegate actuator. The wastegate actuator diaphragm moves when the boost pressure exceeds 7 psi. Then, the flapper opens.
See here:
http://member.newsguy.com/~gtfour/techn ... fo%20Turbo

Here's the wastegate in the bottom left, with the rod that goes to the turbine housing to open the wastegate flapper.
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Postby theUNYTEDone » Tue Jan 31, 2006 6:58 am

thanks much! so there wouldn't really be a way for it to leak externally, would there?
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Postby Stubble » Wed Feb 01, 2006 4:54 am

Technically not "externally", because leaks wil join the exhaust flow. But if it leaks, it will prevent the turbo from spooling quickly, or if the leak is severe enough, keep the turbo from hitting full boost. However, the flapper should be wide open at full boost/max VE, so if leaks enough to keep you from full boost, then it is jammed open.

Ideally, the wastegate stays shut right up until the time that the boost pressure exceeds the wastegate actuator setting, and then it instantly opens to keep boost at that pressure.
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Postby 98RACE » Wed Feb 01, 2006 4:15 pm

Stubble wrote:Technically not "externally", because leaks wil join the exhaust flow. But if it leaks, it will prevent the turbo from spooling quickly, or if the leak is severe enough, keep the turbo from hitting full boost. However, the flapper should be wide open at full boost/max VE, so if leaks enough to keep you from full boost, then it is jammed open.

Ideally, the wastegate stays shut right up until the time that the boost pressure exceeds the wastegate actuator setting, and then it instantly opens to keep boost at that pressure.


HUMM!! You just got me thinking!!! When you say preventing the turbo from spooling quickly, just how fast should it spool?? At what RPM should I start to fell deacent power???
We seem to have a on/off power felling in our ice racer, almost like a 2 cycle hitting its power band. This happens around 3000RPM when the car seems to just take off like a bat out of hell.

Do you think this could be caused by a leaking wastgate??

We seem do hit full boost at about 8-10psi.

Dave

Sorry to hyjack this thread.
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Postby fsmtnbiker » Wed Feb 01, 2006 4:30 pm

98RACE wrote:We seem to have a on/off power felling in our ice racer, almost like a 2 cycle hitting its power band. This happens around 3000RPM when the car seems to just take off like a bat out of hell.


That sounds like perfectly normal operation to me.
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Postby Guest » Wed Feb 01, 2006 5:52 pm

fsmtnbiker wrote:
98RACE wrote:We seem to have a on/off power felling in our ice racer, almost like a 2 cycle hitting its power band. This happens around 3000RPM when the car seems to just take off like a bat out of hell.


That sounds like perfectly normal operation to me.


I guess Im more use to a smaller turbo that starts to spool lower..
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Postby 98RACE » Wed Feb 01, 2006 6:36 pm

^^^That we me!! What the hell is up with this forum some times????
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