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
00 Dakota Sport 90000kms 4.7l, 97 Grand Prix GT, 05 Bigfoot truck camper, 56 Ford f600, 02 Polaris Scrambler 400, 97 Polaris 900 watercraft, 97 Yamaha 700 Mountain Max.