David,
The dirt engine is on gas so I don't get the cooling effect that the alcohol provides. I like to see 200* on the water and 220* on the
oil for both cars on the track, but 230* on
oil doesn't worry me at all. I too, like to see 180* on water before getting on it, though I don't always have that luxury with the dirt car. Often I get the green with only 150* on the water, not a good way to treat a motor.
I've never run without a cooler so I can't tell you how much the cooler lowers temps on my cars. I can tell you this about
oil/air vs oil/water in a dirt Late Model application: about 10* cooler on water and oil is common when going from the built-in cooler to separate ones. Good Luck.
Scott