See that's something I have noticed. Not one person (that I know of) who has done an SVT engine swap has replaced the radiaor with the SVT one! And seem to run fine. But then why did SVT make the radiator larger for the SVT car??
Well, here is a thought. THE SVT also has a "doughnut" water to oil cooler. So the SVT radiator is essentially cooling both coolant and oil, the stock rad is cooling only coolant. Perhaps the stock rad is still doing OK on the coolant but remember the oil does 50% of the cooling in the Duratec. So, whats your oil temp??? You may have heard Terry talk about oil temps.. And do you really believe that water temp gauge is even accurate? Just food for thought/disscusion.
