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Registered User
Join Date: Aug 2007
Location: The Golden State
Posts: 1,533
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Spring length is 6.25in and wire size is 5mm.
Thanks Fred/All
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Rod... 2010 - 997 PDK, Black on Black, Daily driver. 1987 - 930 Grand Prix White, Not looking for crazy HP, just harmony! |
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Registered User
Join Date: Aug 2007
Location: The Golden State
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bump
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Rod... 2010 - 997 PDK, Black on Black, Daily driver. 1987 - 930 Grand Prix White, Not looking for crazy HP, just harmony! |
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beancounter
Join Date: Jan 2008
Location: Weehawken, NJ
Posts: 3,627
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I had the same issue with my '79 with the boost guage pegging. Have you tried bench testing the wastegate to see if you can get the valve to open? In my case, the valve would not open, but air was leaking past the valve stem. When I opened it up, I found two springs in there. When I ran it with only one spring, it wasn't pegging the boost guage, but was not getting full boost due to the leakage at the valve stem. I sent it off to a machine shop and after looking at it, they said to toss it in the trash and get a new one. I put on a TIAL with a .8 bar spring and its regulating boost correctly and the factory guage seems to be reasonably accurate as well.
jacob |
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Registered User
Join Date: Aug 2007
Location: The Golden State
Posts: 1,533
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Jacob, thanks for posting and welcome aboard!
Spring in, I can barely get the valve to move. I’m not a girly man, but dam I’m sure I can bench press 1bar=14.5psi (unless my math is whacked) ![]() Spring out, everything moves silky smooth. Enough already, I am buying a stock spring but PP doesn’t sell them, anyone know a source, PM me, else PM me in a few days for a source.
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Rod... 2010 - 997 PDK, Black on Black, Daily driver. 1987 - 930 Grand Prix White, Not looking for crazy HP, just harmony! |
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Registered User
Join Date: Jul 2006
Location: S. Florida
Posts: 7,289
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The factory boost gauge in the tach measures air pressure above the throttle butterfly in the intercooler or the intermediate blow off manifold.
There is always pressure loss through the restriction of the throttle body, especially at part throttle and the boost pressure the intake manifold sees will always be less. This is one of the reasons a mechanical boost gauge tee'd into the power brake booster hose, which is plumbed to the intake manifold is much more accurate as far as what the motor is actually seeing. |
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beancounter
Join Date: Jan 2008
Location: Weehawken, NJ
Posts: 3,627
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Cl8ton,
Even with the .8bar spring, I wasn't able to push open the valve by hand. I rigged up a hose to a bicycle pump (with pressure gauge) and used it to pressurize the wastegate. I used the same set-up to test the over-boost cutoff switch as well. |
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Smart quod bastardus
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You guys have to remember that the area under the rubber diaphragm in the WG housing multiplies the pressure of 1 bar to get force to open the valve. If you look at the cross sectional area of the the WG housing, multiply that by 1 bar and that gives you a ruff idea of the actual spring preload you need to overcome to open the valve. Alot more than 14.5 lbs.
The best solution is to order a new 0.7 or 0.8 bar spring to be sure. Make sure you run a boost gage in the clock hole tee'd into the brake booster for accuracy. Tach gage is useless.
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1979 930 Turbo....3.4L, 7.5to1 comp, SC cams, full bay intercooler, Rarlyl8 headers, Garret GTX turbo, 36mm ported intakes, Innovate Auxbox/LM-1, custom Manually Adjustable wastegate housing (0.8-1.1bar),--running 0.95 bar max ---"When you're racing it's life! Anything else either before or after, is just waiting" |
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Smart quod bastardus
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hey cl8ton,
PM sent. Fred
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1979 930 Turbo....3.4L, 7.5to1 comp, SC cams, full bay intercooler, Rarlyl8 headers, Garret GTX turbo, 36mm ported intakes, Innovate Auxbox/LM-1, custom Manually Adjustable wastegate housing (0.8-1.1bar),--running 0.95 bar max ---"When you're racing it's life! Anything else either before or after, is just waiting" |
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Registered
Join Date: Aug 2005
Location: Michigan
Posts: 3,337
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I would test the boost gauge sending unit. That may be why you have an inaccurate reading.
Turbo Boosting Gauge/Vac Leak
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Bill Last edited by wcc; 01-22-2008 at 02:16 PM.. |
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Registered
Join Date: Jan 2008
Posts: 991
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I'm getting WG woosh starting at about .6 bar but I still get to the stock spring's .8 max. What is the woosh telling me? Thanks
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Registered
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I would go with an Autometer 0-35 PSI guage and see what is really going on. After that I would get a nice Tial WG with a .8 Bar spring so you have something that is easily adjustable (via cheap spring swap-out). If your OB switch isn't installed get a new one in there now..
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Gary R. |
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Registered
Join Date: Apr 2006
Location: New Zealand
Posts: 3,562
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Quote:
Alan |
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Macht Schnell
Join Date: Jun 2003
Location: PSL, FL
Posts: 861
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Quote:
When I was younger and dealing with decompression sickness patients. A common test is grip strength. I usually could squeeze about 175# on the grip strength test that maxed out at 200#. Most strong folks were well under 100#. I used to squeeze those grip exercisers and break one every 2 weeks or so. Of course that was a long time ago!! I noticed on my TIAL with a 1 Bar spring that I didn't have a hope in hell of moving that valve with my thumb! I kinda did the 1 Bar/14.7# math in my head and figured there was some kinda fulcrum multiplier inside that wastegate. Les
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---Les Garten---85 930, Andial IC, GHL Headers, Fabspeed Dual, K-27 HF2, 3.4 JE Full Finned 7.5:1 CR, 964 CAM'd, Carerra 3.2 Manifold Cut/Flipped, Tec3r, Siemans 55#, GSF Fuel Rails, Clewett Crank Trigger, Clewett Cam Trigger,Dual Plugged, ARP Head Studs/Rod Bolts, Clewett Wires.Tial 46mm WG, Tial 50mm BOV, WEVO Shifter,934 Boost Gauge, Wideband EGO Sensor/Gauge, C2T Head Gaskets, '88 MB 300TE,BMW R100RT |
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Registered User
Join Date: Aug 2007
Location: The Golden State
Posts: 1,533
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Hehhhh, I put a .8 spring in and even with my (old man) Kung-Fu grip, that bugger wouldn't move!
Going on faith brothers!
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Rod... 2010 - 997 PDK, Black on Black, Daily driver. 1987 - 930 Grand Prix White, Not looking for crazy HP, just harmony! |
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Smart quod bastardus
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Lets see, the wastegate can or diaphragm diameter is roughly 3 inches in diameter. Cross sectional area is then Pi *d^2/4 or 7 square inches.
Multiply that by 14.7 psi and you get about 104 lbs of force needed to crack open the wastegate valve. Seems reasonable you aint gonna do that with your thumb. Alan L measurements seem in the ballpark then. My dimensions are just a guess from memory. Pretty cool stuff.
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1979 930 Turbo....3.4L, 7.5to1 comp, SC cams, full bay intercooler, Rarlyl8 headers, Garret GTX turbo, 36mm ported intakes, Innovate Auxbox/LM-1, custom Manually Adjustable wastegate housing (0.8-1.1bar),--running 0.95 bar max ---"When you're racing it's life! Anything else either before or after, is just waiting" |
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Registered
Join Date: Feb 2008
Location: Bayside Wi
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