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Old 04-24-2007, 12:02 PM   #4 (permalink)
Diesel Nut
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Join Date: Jan 2006
Location: Okanagan BC. Canada
Posts: 771

How is the spring rate you are talking about arrived at. It is not similar to how valve springs are tested. I was not able to get this type of spring rate info when I was looking for springs at the auto parts store, maybe a more specialized shop could get those figures?

I was able to test the cracking/opening pressure of the wastegate with the spring at its operateing hieght for the GM-3 by using a simple fish scale. Through trial and error I found that a larger dia. spring with more coils per inche gives gives a much more consistant wastegate operation, no spikes or droping of boost after wastegate opens. The wastegate spring I have now is consistant to within 1 psi no matter how the truck is operated.
1993 F 6.5 turbo/desiel 3/4 ton HD, long box, 2wd, 4L80E trans., 3:42 rear gears, 170,000 miles, Heath 4" exhaust, dual thermastate/HO water pump upgrade, DB2 pump turned up 1/4 turn, 97+ air cleaner, removed snorkle, Autometer EGT/Trans/Boost gauges, manual torque converter lockup switch, Heath turbo master, Okanagan BC. Canada

86 Monte Carlo SS, Original Owner 55000 miles. 2002 Dodge Dually 3500 24v cummins
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