Geomeo
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« on: July 03, 2020, 08:55:14 AM »
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Hi I’m currently installing a turbo on my 2003 1.8 tt and I’m trying to figure out a range I guess. So the turbo is a gtx2871r which from the specs can handle up to 30 psi of boost and can be set as low as 9 psi via its own external wastegate. I’m assuming the 9 psi is a maximum value that it can be set at? I’m not sure the purpose is in that. The manifold I have has a flange for a 38mm wastegate. Looking at the specs of the 38mm ones some can go as low as 4 psi. But they never specify a max boost of something like 30. So I’m a little confused. And I don’t see a range for the n75 valve. Basically trying to deliberate whether or not to buy a 38mm wastegate because I have to fab a downpipe anyway or should I just use its own and cap off the 38mm flange?
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fknbrkn
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mk4 1.8T AUM
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« Reply #1 on: July 03, 2020, 09:33:42 AM »
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Wtf
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Geomeo
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« Reply #2 on: July 03, 2020, 09:54:08 AM »
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Lol I did post this in the noob questions so I’m not entirely sure your response is valid.
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nyet
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« Reply #3 on: July 03, 2020, 01:03:16 PM »
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You want to balance low cracking pressure for part throttle drivability vs high spring pressure to keep the WG closed.
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Geomeo
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« Reply #4 on: July 03, 2020, 02:31:37 PM »
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The wg is not open circuit for the most part?
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nyet
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« Reply #5 on: July 04, 2020, 12:22:09 AM »
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The wg is not open circuit for the most part?
I have no idea what this means. |
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Geomeo
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« Reply #6 on: July 04, 2020, 09:22:43 AM »
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The wastegate. Is it not open most of the time?
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IamwhoIam
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« Reply #7 on: July 04, 2020, 09:35:30 AM »
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Are you drunk?
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I have no logs because I have a boost gauge (makes things easier)
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nyet
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« Reply #8 on: July 04, 2020, 10:35:17 AM »
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The wastegate. Is it not open most of the time?
It is open when it needs to be open, closed when it needs to be closed. What % of the time is a turbo producing more pressure than requested? |
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Geomeo
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« Reply #9 on: July 04, 2020, 11:52:25 AM »
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It is open when it needs to be open, closed when it needs to be closed. What % of the time is a turbo producing more pressure than requested?
I don’t know. |
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Geomeo
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« Reply #10 on: July 04, 2020, 11:54:09 AM »
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Are you drunk?
Nope. Are you? |
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adam-
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« Reply #11 on: July 04, 2020, 12:13:22 PM »
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You need a gate, the turbo doesn't have one (according to your original post). Set the base pressure to whatever spring you fit, and use the N75 to control after that.
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Geomeo
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« Reply #12 on: July 04, 2020, 02:18:16 PM »
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The base pressure of?
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dilly
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« Reply #13 on: July 04, 2020, 07:15:35 PM »
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Hi I’m currently installing a turbo on my 2003 1.8 tt and I’m trying to figure out a range I guess. So the turbo is a gtx2871r which from the specs can handle up to 30 psi of boost and can be set as low as 9 psi via its own external wastegate. I’m assuming the 9 psi is a maximum value that it can be set at? I’m not sure the purpose is in that. The manifold I have has a flange for a 38mm wastegate. Looking at the specs of the 38mm ones some can go as low as 4 psi. But they never specify a max boost of something like 30. So I’m a little confused. And I don’t see a range for the n75 valve. Basically trying to deliberate whether or not to buy a 38mm wastegate because I have to fab a downpipe anyway or should I just use its own and cap off the 38mm flange?
the 9 psi is the cracking pressure of the internal wastegate ie. that is the lowest amount of boost this turbo can create unless the wastegate actuator is changed to a lower spring pressure. 30 is the max the turbo can produce reliably without blowing the seals. external wastegates can be anywhere from 1 psi to x amount of pressure depending on what spring is in it. cap off your manifold wastegate port and use the gtx's internal gate. the n75 is just a solenoid that lets pressure through to the wastegate at a specific pressure specified by the ecu. you request 25psi and once the ecu sees manifold pressure at 25 it opens the n75 and lets pressure to the wastegate thus opening it and regulating boost pressure. |
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Geomeo
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« Reply #14 on: July 05, 2020, 08:40:57 AM »
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So does the turbo make any pressure after cracking or what’s the psi value after cracking? I’m assuming by cracking you mean cracking opening of the flap? I guess this is going to be a lot of trial and error. How do I make sure overboost will not happen? Or typically what cracking pressure do I need to be set to to run 300whp @ 5k rpm?
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