Radiator Size ????

Scatpack1 said
I have a Demon with a 340 stroked to 408 CI sitting in my garage.
What would you think would be the minimum radiator capacity to keep running/cruising temperatures down?
It has what looks to be a six cylinder size aluminum 3 row radiator in it now. It is constantly getting hot when driving. This is an x race car, I assume the prior owner left the small radiator in it from when he drag raced it. I may need to get another radiator, but don't want to buy it twice, if that makes sense. What do you guys think? I have always ran big block cars and this is my first small block.
Car has an electric fan set to come on at 180*. No fan shroud, but an aluminum plate that does not look to me like it would work very efficiently.

I‘m not sure why you are asking about the minimum radiator size you can get away with, because that‘s a bad rabbit hole to go down.

As has been said, get the biggest TWO CORE radiator you can get in there. Two big cores will out cool 3 or 4 smaller cores all day long.

Then you should be buying a high flow water pump. Flow kooler or Milodon will work.

Then you should be using a high flow thermostat. The best out there (and it ain’t cheap but worth every penny) is the Stewart Components thermostats. They are second to none.

And then, as pointed out above you need to get the water pump speed correct. Never and by never I mean never ever slow the water pump down to less that crank speed (under driven). You may save 2 HP but you’ll lose 12-15 HP because you can’t control engine temperature on hot days. And that makes the same engine much more sensitive to detonation.

So, a big two core radiator with a high flow pump and thermostat and turning the water pump at least crank speed (overdriving the pump is even better unless you are shifting at 8500 plus and then you need to worry about blowing the fan apart…unless you have an electric fan) and you can drive through downtown hell on the hottest summer day in slow traffic and your engine temperature will be under control.