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Replacing or refurbing wastegate (Tial, perhaps?)
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bureau13  



Joined: 07 Sep 2017
Posts: 480
Location: South Florida
PostPosted: Thu Nov 28, 2019 10:33 am    Post subject: Reply with quote
Right, about spring rate, of course that would make it different. Just trying to get an idea of, say stock US spring of 0.5 bar or so, what my boost would be limited at. I know the wastegate is supposed to be operated with the control line in place, but exhaust backpressure will crack it open at some point.

Carrera RSR wrote:
All depends on the waste gate spring installed.......0.5, 0.7, 1.0 bar boost springs?? Needs boost line pressure to control the valve, not exhaust

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1982 931
1986.5 Silver 928S
2007 Hummer H3 (Daily Driver)

Past lives (I miss them all):
2004 RX-8 (Wrecked)
1993 RX-7 (Sold)
1987 RX-7 Turbo II (Sold)
1985 RX-7 GSL (Stolen)
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Fasteddie313  



Joined: 29 Sep 2013
Posts: 2596
Location: MI
PostPosted: Thu Nov 28, 2019 4:35 pm    Post subject: Reply with quote
I think it depends a lot on your setup..

How big your WG is, how much backpressure your turbo makes where, Your VE, etc..

The 931 has a very big WG, so extremely high boost with no line attached I think..

I don't know, have never tried it, but I don't think their is any end in reasonable sight..
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Cedric  



Joined: 27 Aug 2004
Posts: 2608
Location: Sweden
PostPosted: Thu Nov 28, 2019 4:56 pm    Post subject: Reply with quote
bureau13 wrote:
Right, about spring rate, of course that would make it different. Just trying to get an idea of, say stock US spring of 0.5 bar or so, what my boost would be limited at. I know the wastegate is supposed to be operated with the control line in place, but exhaust backpressure will crack it open at some point.

Carrera RSR wrote:
All depends on the waste gate spring installed.......0.5, 0.7, 1.0 bar boost springs?? Needs boost line pressure to control the valve, not exhaust


Based on my experience with a popped of boost control line i dont think you will ever experience the point where the WG self opens, RIP stock engine

If you measure or calculate the spring rate of the WG spring its not that hard to make a fairly good calculation of the needed back pressure based on that and the WG valve area. But it will probably end up in a very big number.
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bureau13  



Joined: 07 Sep 2017
Posts: 480
Location: South Florida
PostPosted: Fri Nov 29, 2019 2:11 am    Post subject: Reply with quote
Interesting. Thanks for the info, guys.
_________________
-----------------------------------------
1982 931
1986.5 Silver 928S
2007 Hummer H3 (Daily Driver)

Past lives (I miss them all):
2004 RX-8 (Wrecked)
1993 RX-7 (Sold)
1987 RX-7 Turbo II (Sold)
1985 RX-7 GSL (Stolen)
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