Well it's hard to say. Since I've always had them, I don't know what's it like not to have them. But I measure the temperature of places like my intake manifold, heads, etc. and I keep a consistent temperature of 165 in the IM and carb area. Heads are warmer than that, coolant and
oil temps are at 195 or so. When my fans kick on, you can feel the heat blow out of the wheel wells and it seems to be considerable, but so is the heat off my charcoal grill, so it's really hard to say.