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Old 06-27-2018, 02:47 PM
v8volvo v8volvo is offline
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Join Date: Jun 2009
Location: Montana, USA
Vehicle: '86 745, '83 764
Posts: 1,618
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There appears to be an overboost pressure relief valve in the front of the intake manifold on the TIC motors similar to the non IC TD motors. This is probably the piece you are referring to?

The purpose of the microswitch is to turn on the warning light on the instrument panel if that valve is opened by excessive boost pressure, since it assumes if this happens the turbo wastegate or its hose have failed and the engine might be threatened. Increasing the boost with a manual controller should push that valve open and trigger the light when the blowoff valve set to its stock opening pressure. But, you can adjust the screw in the valve to increase the spring preload and the raise valve opening pressure. This should enable you to keep the valve shut and the light off at higher boost pressures, as long as you have a gauge so you know what's going on.

You could also plug or eliminate the relief valve if you decide to run boost pressures high enough that even with the screw turned all the way in it's still blowing off air and turning on the light. But the screw adjustment gives you enough range to run up to around 15-17 psi and the stock turbo and intercooler are close to their limits by that point anyway, so depending on your plans it might give you enough range unless you are going to do other upgrades.

Look forward to hearing how it goes and seeing some photos, those late IC motors are always fun for us to see.
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86 745 D24T/ZF 345k lifted 2.5"
83 764 D24T/M46 155k
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