Uncontrollable boost...Mystery of the ages
#81
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In one place it says the evolution wastegate is good for 500hp and in another it says 400hp. Does anyone know what the diameter is?
At this point it would be interesting for Brad to chime in. Sure would be nice to get Turbonetics take on this.
At this point it would be interesting for Brad to chime in. Sure would be nice to get Turbonetics take on this.
Last edited by 35ounces; 12-06-2005 at 06:22 AM.
#82
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The Evoultion is 36mm which is pretty small for this type of application. The Greddy Tial wastegates are 38mm and there are two of them.
I am not ready to agree that the wastegate is too small, as so many dozens of people, inlcuding Peking's car which I tuned with his 3 inch exhuast, have had no problems at all holding the preset boost.
I am sure that space constraints kept TN from including a larger wastegate.
I am not ready to agree that the wastegate is too small, as so many dozens of people, inlcuding Peking's car which I tuned with his 3 inch exhuast, have had no problems at all holding the preset boost.
I am sure that space constraints kept TN from including a larger wastegate.
#83
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Jet indicated that he saw a significant decrease (about 1.5 PSI) in peak boost value by adding in the silencers to his mufflers, which effectively decreases the diameter from 3" to 2". So we have a demonstration of backpressure helping to control gate operation. Slowing down the turbine seems to have a bigger effect on gate operation than backpressure. The question is what does it do to the tune, and is it better to have a restrictive exhaust on this kit, or a bigger wastegate (especially given the tight spaces that the gate sits in.
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Of course more backpressure will effect the turbo but I'd certainly prefer to control boost via precise wastegate operation then try to do it with backpressure which is just making the turbo work harder.
It would certainly be nice to know if it is the wastegate not flowing enough, or the dump tube design, or just an issue with your WG signal.
It would certainly be nice to know if it is the wastegate not flowing enough, or the dump tube design, or just an issue with your WG signal.
#85
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Originally Posted by JETPILOT
Relatively low boost demand.... 8-9PSI requiring the wg to operate near max potential. At least lets agree that the less boost you demand the more the WG has to flow.
What I dont understand is why a few guys running the Greddy Evo mod'd are having this problem, and people are thinking maybe its the exhaust is to free flowing, but the Borla TD guys such as Laww are not having this issue, and they are both 2.5" TD exhaust(before the reverse y-pipe of course), and should be flowing very similarly. Could it just be a bad coincidence that guys running the Evo2 are having this issue, or does it pertain to their exhaust systems?
Last edited by Alberto; 12-06-2005 at 07:22 AM.
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Originally Posted by Alberto
IIRC the T-netics Z that AAM did for Modified mag was pushing 14psi with no issues controlling the boost, so how would you explain your theory against that car which made over 450whp and 500ft/lbs?
What I dont understand is why a few guys running the Greddy Evo mod'd are having this problem, and people are thinking maybe its the exhaust is to free flowing, but the Borla TD guys such as Laww are not having this issue, and they are both 2.5" TD exhaust(before the reverse y-pipe of course), and should be flowing very similarly. Could it just be a bad coincidence that guys running the Evo2 are having this issue, or does it pertain to their exhaust systems?
What I dont understand is why a few guys running the Greddy Evo mod'd are having this problem, and people are thinking maybe its the exhaust is to free flowing, but the Borla TD guys such as Laww are not having this issue, and they are both 2.5" TD exhaust(before the reverse y-pipe of course), and should be flowing very similarly. Could it just be a bad coincidence that guys running the Evo2 are having this issue, or does it pertain to their exhaust systems?
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I hate these dueling threads!
He made a point, that may be valid. At low boost pressure the WG has to flow near max capability and it may not be able to do that. That would leave us with a lack of boost control at low boost levels with ideal flowing exhausts.
He made a point, that may be valid. At low boost pressure the WG has to flow near max capability and it may not be able to do that. That would leave us with a lack of boost control at low boost levels with ideal flowing exhausts.
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Originally Posted by 35ounces
I hate these dueling threads!
He made a point, that may be valid. At low boost pressure the WG has to flow near max capability and it may not be able to do that. That would leave us with a lack of boost control at low boost levels with ideal flowing exhausts.
He made a point, that may be valid. At low boost pressure the WG has to flow near max capability and it may not be able to do that. That would leave us with a lack of boost control at low boost levels with ideal flowing exhausts.
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Originally Posted by MIAPLAYA
While this is close I won't say thats exactly accurate. Consider it this way...with higher boost the wastegate opens for LESS amount of time per cycle. BUT when it does open due to the increased air flow from the higher horespower it has to flow MORE air then it does at 8 PSI and 380 HP. So then the possiblilty would be that it is not able to cycle FAST enough at lower boost not that it cant flow enough air.
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Originally Posted by 35ounces
If that was the case then boost would SPIKE but Kelly is seeing consistent high boost. Also, the boost controller that Kelly installed would help resolve the issue.
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LOL. I am not convinced that the WG is maxed out either but is an interesting theory.
Just for interests sake do we know what other WG's might fit? Do any of the TurboSmart wastegates fit?
Just for interests sake do we know what other WG's might fit? Do any of the TurboSmart wastegates fit?
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Originally Posted by 35ounces
LOL. I am not convinced that the WG is maxed out either but is an interesting theory.
Just for interests sake do we know what other WG's might fit? Do any of the TurboSmart wastegates fit?
Just for interests sake do we know what other WG's might fit? Do any of the TurboSmart wastegates fit?
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Ok, it's pretty simple. HP is not the deciding factor on what waste-gate to use. It is CFM. When using the factory exhaust your exhaust gas will flow the least direction of resistance. In your case was your waste-gate. Now with your high flow exhaust system that path of the least resistance is your turbocharger. Two things can cause this, the incorrect placement of your waste-gate or undersized waste-gate. A lower spring tension on the waste-gate could help or replacing with a waste-gate that can flow more cfm.
Thanks,
Jermaine~
Thanks,
Jermaine~
#96
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Originally Posted by BlackTuner
Ok, it's pretty simple. HP is not the deciding factor on what waste-gate to use. It is CFM. When using the factory exhaust your exhaust gas will flow the least direction of resistance. In your case was your waste-gate. Now with your high flow exhaust system that path of the least resistance is your turbocharger. Two things can cause this, the incorrect placement of your waste-gate or undersized waste-gate. A lower spring tension on the waste-gate could help or replacing with a waste-gate that can flow more cfm.
Thanks,
Jermaine~
Thanks,
Jermaine~
Wastegate piston travel is also important to the total CFM flow as is piston size, as well as the angle the wastegate is mounted to the exhaust stream. 90 degree mounting angle works well with the stock exhaust but may become a limiting factor and slow gas flow in a car with an open exhaust where the gate is required to flow more.
Respect
JET
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Originally Posted by JETPILOT
Exactly.....
Wastegate piston travel is also important to the total CFM flow as is piston size, as well as the angle the wastegate is mounted to the exhaust stream. 90 degree mounting angle works well with the stock exhaust but may become a limiting factor and slow gas flow in a car with an open exhaust where the gate is required to flow more.
Respect
JET
Wastegate piston travel is also important to the total CFM flow as is piston size, as well as the angle the wastegate is mounted to the exhaust stream. 90 degree mounting angle works well with the stock exhaust but may become a limiting factor and slow gas flow in a car with an open exhaust where the gate is required to flow more.
Respect
JET
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Originally Posted by BlackTuner
Ok, it's pretty simple. HP is not the deciding factor on what waste-gate to use. It is CFM. When using the factory exhaust your exhaust gas will flow the least direction of resistance. In your case was your waste-gate. Now with your high flow exhaust system that path of the least resistance is your turbocharger. Two things can cause this, the incorrect placement of your waste-gate or undersized waste-gate. A lower spring tension on the waste-gate could help or replacing with a waste-gate that can flow more cfm.
Thanks,
Jermaine~
Thanks,
Jermaine~
By the way, what size piping is the Greddy evo2? From what I understand it has pretty small piping.
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Originally Posted by MIAPLAYA
I agree 100%. Its just hard for me to accept it 100%. Some cars have dropped the exhaust all together and not had an increase in boost pressure. While others have just bolted on a 3" exhaust and increased boost pressure. I just talked to Turbonetics and they have an 05 Z in the shop right now. They are going to research this today on that car. I should know sometime today or tomorrow what they come up with.
Jermaine~