Serious ground runs today, and I installed the belly radiator that has been on my hangar shelf for 2 years. Yesterday I went to over temp 180 degrees in about 5 to 6 minutes of ground run (OAT 87 degrees, cowlings off). With the belly radiator I ran for 20 minutes today and the temp stabilized after about 12 minutes at 165 or so. To support the radiator, I used 2 U-Bolts thru the cockpit floor, hooking over the diagonals that go from the center aft to the sidewall. I put the bolt thru the plywood, below the carpet where it didn't interfere at all. I used a cut-away rectangular channel mounted to the U-bolts, and then bolted the radiator to the channel. The channel is about 2" in depth, pulling the radiator down a bit for cleaner air (yes, and more drag). Silicon tubing connected the radiator to the pump output, and the return goes to the right nose radiator. I set the warp drive to 15 degrees of pitch at the tip, and today ran to full throttle in the chocks, and got 5970 RPM, which is close enough for me to take it to flight. EGT and fuel flow are working fine, so I should get good performance data for the group.High speed taxi tomorrow, if the winds behave.