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Old 04-23-2007, 04:07 PM   #3 (permalink)
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Join Date: Jun 2004
Location: Indiana / Wisconsin
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Originally Posted by Tracy;1737011;
When I was making a wastegate for my 93 with GM-3 I found that a spring that would crack/compress at 16 in/pds would get me 8psi boost. Boost lever and spring in stock location and angle . Not sure why I got different figures than you, maybe differant turbo and not talking apples to apples?
Tracy -

The spring rate will determine how the wastegate behaves once it cracks open, not the maximum level of boost. When you talk about a spring giving you X lbs of boost before the wastegate cracks, that has more to do with spring pre-load than spring rate. The pre-load is adjustable (hence the ability to adjust boost) by cranking down the wing nut on the threaded rod. I could lower the max boost on my setup as well, by backing the wing nut off, but that would not change how it reacts once the wastegate cracks open.

I have seen many people here asking how much spring or what kind of spring to use on a homemade T/M. This will give them an idea of what kind of spring to purchase. McMaster is a great place to find springs with specs so you can get one similar to mine AND some with a slightly and or slightly lower rate if you choose...



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