like I said any time the car is moving at more than 30/35 mph, the clutch is slipping and the fan, because it presents such a huge resistance to the clutch, it free-wheels.
And what price can you put on peace of mind, stuck in traffic, listening to that 7-blader do it's thing. Spend the money once, on the right parts, and forget about it.
BTW did I mention my rad is from a 73 Dart 318/904 with A/C?
It don't matter how much you spend on a rad; it cannot make the temperature of the coolant in a running engine drop, until the air flows thru it. And, IMO, if you force the system to try to run at 160*F, well, yur gonna need a premium HD system. Whereas my 48 year-old rad is doing just fine, at 205 with a 7# cap.
I run the lo-pressure cap for a few reasons; 1) my system runs rock-solid 205 to 207. So I don't need the "protection", and 2) My hoses last forever. 3) My engine has alloy heads, so those are like big old heat-sinks pumping massive amounts of heat straight into the underhood area, making the job easier on the rad. BUT, it takes that hi-efficiency 7-blader to pump all that hot air downhill and underneath the car. A flex-fan is hopelessly outclassed. The 5-blader on the Mopar viscous clutch never stood a chance. Even direct-driven the hi-efficiency 5- blader couldn't do it. It did fine with the hood open, and engine idling. It did fine over 35mph with the back of the hood raised to let the heat out. But drive it slow, and watch the gauge start climbing. I mean I tried everything I had hanging in my shed; and more.
Not until the 7-blade went on with the Ford clutch, could I lower the hood to where it belonged, and forget about the gauge.
Your results may vary.lol.