guys,,im still not convinced,,moving water faster thru the engine and radiator is the total answer...with the 180 stats wide open @ 70 mph turning 2500 rpms,ambiant temp @90 degrees july hot...just flatland interstate running...the temp rises depending on load even more..with a good clean system temps can hover at 205/210...if the water travels thru the radiator too fast, heat transfer is poor...back out of throttle to 55 mph and temp falls..that speed is what the engine was designed for or less..factor in luggage tools extra passengers...if engine is bored out.heat is closer to the water,which heats up faster,certain amount of scale in the water jacks rear cyls retard heat transfer...on and on and on..i run mechanical gages for 20 years..i pay close attention to my engine,i know its habits and likes and dislikes,,my block has 190,000 miles..bored to 060..mild cam..does well and is predictable..just my 2 cents worth.