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Join Date: May 2002
Location: Georgia
Posts: 3,172
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cutting wastegate spring
Does anyone know how much needs to be cut off of the stock wastegate spring to reduce the pressure needed to activate the gate? I want to have to have about .5-.6 max for a 3.2 conversion.
thanks, Ben
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1986 3.2 Carrera |
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11-10-2007, 06:01 PM
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Metal Guru
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I have a .7 bar OE spring here that's 157 mm long. Maybe cutting to 150 mm will give you what you are looking for.
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Paul B. '91 964 3.3 Turbo Port matched, SC cams, K27/K29 turbo, Roush Performance custom headers w/Tial MV-S dual wastegates, Rarlyl8 muffler, LWFW, GT2 clutch & PP, BL wur, factory RS shifter, RS mounts, FVD timing mod, Big Reds, H&R Coilovers, ESB spring plates- 210 lb |
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11-10-2007, 06:26 PM
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A fellow Pelacanite
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Surely they are different thickness too?
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1981 UK 930. G50/01 shortened, 964 3.8RS Fibreglass Body Kit, 18" Alloys 8.5" F & 10" R, 225's F & 285's R, Special Colour Metallic Blue Paint, FIA Sparco Evo's, A/C and Air Pump removed, Electronic Boost Controller, GHL Headers, Tial46 WG. Fitting - New service kit. Needs Fitting - Innovate XD-16 Kit, Kokeln IC. Stephen's K27 HFS, EVO Intake Assy & his Modded USA Fuel Head. 1983 UK 911 3.2 Carrera Sport Coupe. Black, Black Leather with Red Piping, Black Alloy Gear Knob, K&N Air Filter Element, Turbo Tie rods. Needs Fitting - K&N CO Sensor, Round A/F Dial Gauge, Factory Short Shift Kit. http://www.danasoft.com/sig/Iamnotanumber.jpg |
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11-10-2007, 06:33 PM
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Cutting the spring will increase your boost.
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Dean 911 SC turbo, 3.0L 930 motor, G50, 930 brakes, DTA EFI, 352 RWHP DynoDynamic dyno, |
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11-11-2007, 03:31 AM
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Dean, I believe that the wastegate spring is able to be cut to reduce the spring rate. Why do you think it is the other way? Have you done this mod? Thanks in advance for any help.
I remember that others have done this and have found the threads but there is not any mention of how much was cut. Any one have first hank knowledge of this mod?
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1986 3.2 Carrera |
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11-11-2007, 04:05 AM
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Ben,
When you cut a spring, it increases the force to compress it. And you boost will be higher
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Dean 911 SC turbo, 3.0L 930 motor, G50, 930 brakes, DTA EFI, 352 RWHP DynoDynamic dyno, |
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11-11-2007, 04:12 AM
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Location: Ballston Spa, NY
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Quote:
If you cut the spring the preload on the wastegate diaphram will be lower and thus less boost pressure. Any wastegate spring I've ever cut to modify boost pressure has always resulted in lower boost. I would source a lighter pressure spring before cutting the stock one. Plenty of places to get them online(spring companies)
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Adam Hennessy |
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11-11-2007, 05:45 AM
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Metal Guru
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Dean, if that is true why are higher value wastegate springs progressively longer?
I have 3 springs for the stock wastegate; all are progressively longer and have the same wire diameter. The coil pitch gets smaller from the .7 bar spring to the 1 bar spring. The spring gets packed into the wastegate pretty good. In the case of the 1 bar spring it's length will be reduced by 60% when installed. I think it can safely be said that the 1 bar spring will supply greater compression than the .7 bar spring.
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Paul B. '91 964 3.3 Turbo Port matched, SC cams, K27/K29 turbo, Roush Performance custom headers w/Tial MV-S dual wastegates, Rarlyl8 muffler, LWFW, GT2 clutch & PP, BL wur, factory RS shifter, RS mounts, FVD timing mod, Big Reds, H&R Coilovers, ESB spring plates- 210 lb |
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11-11-2007, 05:51 AM
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just buy a tial and pop a 4 pound spring into it.
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Kris @ Tech9 86' 930/GT-40R Sold  94' Rustang GT daily (long gone) 2008 C6/Z51 Corvette |
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11-11-2007, 11:31 AM
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Cutting a spring to lower the boost may work in that situ.
The fact remains that if you cut a spring, it increases the tension to compress that shorter spring. Hey Paul, I don't know
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Dean 911 SC turbo, 3.0L 930 motor, G50, 930 brakes, DTA EFI, 352 RWHP DynoDynamic dyno, |
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11-11-2007, 04:27 PM
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I wouldn't cut a waste gate spring.
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2014 Cayman S (track rat w/GT4 suspension) 1979 930 (475 rwhp at 0.95 bar) |
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11-11-2007, 06:59 PM
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1991 Porsche 964 Turbo
2002 Porsche 996TT
1979 Porsche 930 3.4
