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Discussion Starter · #1 ·
Were they adjustable or not? My original turbo is long gone. Never really paid attention to the actuator at the time. The turbo on my car now is a GM replacement ( from GM ) purchased in about 2000? The actuator is threaded and adjustable. I was able to adjust it , turned it 2 times , got my boost up from 14 to 16 . It seems to spike to 18 when I initially go WOT, and then settle at a steady 16. Is there a benefit to using a heavy duty one at lower boost levels?

Here are pics of the 2 that I have . The one off the car appears to be an aftermarket one as there is no lock nut on it . That one came off a used turbo I got after my original one died ( ported/stamped cpp).
 

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The original ones were not adjustable but if you got the turbo replaced by GM, sometimes you'd get an adjustable one with it. As for spiking you might have a pin hole in one of your vac lines going to the actuator or turbo housing.
 

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an hd will not allow you to set the boost below 17# which is probably too much unless you are running 94 octane or better, or have alky injection.

Spiking becomes a greater problem as one increases the boost as the shorter rod may not allow the wastegate to open as much. Increasing the size of wastegate hole often helps this problem...long as it is not increased so much that the puck no longer seals, of course.

And, as stated above, a pinhole or such in the lines might cause a problem.
 

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Spiking becomes a greater problem as one increases the boost as the shorter rod may not allow the wastegate to open as much
Some people, who didn't want to use an adjustable actuator, or make one, have added an external spring. Not sure exactly how they mounted it, but it pulled the actuator rod, adding to the preload and increasing boost, without affecting the "stroke" of the wastegate puck.
 

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The boost 'spiking' could be normal. The chip will let the engine create more boost in low gears and then start scaling it back say in 3rd gear to the desired setting.
 

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Discussion Starter · #6 ·
Thanks for the replies. I am going to goof with the one thats on the car now and see if I can get it a little higher . I am running a 110/94 mix right now so I should be ok with knock. I may switch to the other actuator just to see if it performs differently . The high boost spike is very quick so I will just keep it under 20 and it should be ok .
 
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