360 Tune Up

But none of my other vehicles does this....and I have 3 SBC's that don't. Ram Air keeps them right at thermostat setting.

I realize there is more work being done and much more heat being generated but the radiator is supposed to be able to handle 6-700 HP, according to Champion. Air flow is the ghost I've been chasing. The under hood temps get pretty high and I'm attributing some of that to headers. I thought about wrapping them and I think that would lower under hood temps but I don't think it will change my coolant temps. It's starting to look like I'm going to have to live with this "as is" and adjust my fan so that it cuts on at about 205. I don't see the point in running it when it's doing nothing to bring the temps down.

What kind of vehicles are your SBC's in, are they also swapped into older-style hot rod vehicles? It sounds like you have an airflow problem, got any pics of your radiator and fan setup? I've always run factory thermal clutch-drive fan and shroud and never had temps creep on the freeway going 80 MPH in my '70 Duster. Might be a case where the shroud for your electric fan obstructs free air flow when you're driving at speed. I'm assuming a mechanical fan isn't really an option though with your custom setup?