Underdrive Pulley Questions

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My 986 had an early RSS underdrive pulley installed in 2009 while shaving off just enough of the timing boss for clearance. When we had the IMS retrofit done a few years later we simply re-installed the stock pulley and everything held together as it should. I had very good reliability with my accessories never overheating and the PS pump never leaked with over 100 track days.

Is it a perfect solution? No. Will it work if you are careful with your installation and save your stock pulley for future engine work? Yes. Shade-tree mechanics shaving down the timing boss smooth is the bane of every engine builder.

Never had a problem with overheating the motor and some have suggested that slowing down coolant velocity may actually improve cooling with longer contact time to absorb/release heat. Ideal heat rise through a heat exchanger or motor seems to be about 40F to get maximum heat transfer. Too fast or too slow and some efficiency is lost. I have not tested this in a 986 with any objective measurement tools, just familiar with heat exchangers and flow rates in my day job. The concept is plausible and my own experience was good.