Is your intercooler properly shrouded? If all of the air that feeds the fan has to first go through the intercooler you should not be having a heat soak issue.
I have a question to add to this discussion.
What do you do to shroud an intercooler that is NOT the full bay type?
I fear that a stock sized intercooler would not allow enough air flow for the fan and it would try to pull hot air from the cracks in the engine tin.
RarlyL8 Motorsports / M&K Exhaust - 911/930 Exhaust Systems, Turbos, TiAL, CIS Mods/Rebuilds
'78 911SC Widebody, 930 engine, 915 Tranny, K27, SC Cams, RL8 Headers & GT3 Muffler. 350whp @ 0.75bar
Brian B. (256)536-9977 Service@MKExhaust Brian@RarlyL8