Here is how I solved the high temperatures during ground runs.  I bought $10 worth of stuff at Lowes, ½ inch PVC, 90 and 45 angles, end caps, and misters for spraying plants in the garden (two in the oil cooler, three for the water cooler).  I hooked it up to the hose, and although water flowed all over the ground, the engine remained within limits.

Before, I could get about 4-5 minutes of high power.  With this spray bar running, I had to push the power up above 2500 RPM to get it to heat up above 135*, then after about 8 minutes at high power, I was still only 185*.

Easy, cheap, and it keeps the cooling system intact.

CHris