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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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Old 11-10-2007, 05:01 PM
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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.
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Old 11-10-2007, 05:26 PM
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Surely they are different thickness too?
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Old 11-10-2007, 05:33 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,
Old 11-11-2007, 02:31 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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Old 11-11-2007, 03:05 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,
Old 11-11-2007, 03:12 AM
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Quote:
Originally Posted by dean View Post
Ben,

When you cut a spring, it increases the force to compress it. And you boost will be higher

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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Old 11-11-2007, 04:45 AM
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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 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, - 210 lb
Old 11-11-2007, 04:51 AM
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just buy a tial and pop a 4 pound spring into it.
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Old 11-11-2007, 10:31 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,
Old 11-11-2007, 03:27 PM
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I wouldn't cut a waste gate spring.
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Old 11-11-2007, 05:59 PM
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