[Dwight]

what is the cfm of the fan?

what do you call overheating?

Several of us are using 2700 and 3000 cfm fans without shrouds with no overheating problems.

I have a small block 354 with 10.7 cr. I run a 195 t-stat and my fan comes on at 205. When I'm sitting at a long red light it will climb to 210 and hold. Fan will kick on and bring it down.

Coach has a 428/461 c.i. KC motor, 3000 cfm fan set to come on at 185. Never gets to 205.
Lainhart has a 487 KC motor with a fan shroud. No overheating problem, it will sit and idle for 35 minutes, no problem.
Both of these KC motors are 9 to 9.5 compression motor with over 600 hp.

The more hp you make, the more heat. Higher compression, more heat.

We have changed our March overdrive pulleys to standard size pulleys. That got rid of the idle overheating and alternater not charging problems.

And my favorite, to much anti-freeze! Never more than 50% but we run 25 to 30% because when it's below 40 degrees our Cobras are inside the garage, nice and warm.
Dwight