I run a 3 core, 26" champion radiator for a .060" over, iron-headed 340 pushing 400+ hp. I've never had cooling issues with it. I use a Ford Contour dual electric fan set up with a programmable controller so I can set the exact temps to run my engine at, and so far that's held up even on 110* days. Cheapest radiator you can buy, works great. $130 OE electric fan. 190* standard thermostat, GMB high volume water pump.
There isn't a radiator manufacturer out there that provides enough data to
really do the calculations to figure out how much heat they'll dissipate or how much water they'll flow. Make assumptions about how much a 1" tube can flow without the friction loss numbers and I can tell you that's all they are, assumptions. The 2 row 1" radiator manufacturer say theirs are best and provide no data to prove it. The 3 and 4 core radiator manufacturers say their radiators are best and provide no data to prove it. None of the websites provide actual data, just a sales pitch.
I'm putting together the same setup but 383 instead of 440. I've seen both of these radiators, and I'm certain the two 1" tubes will be far more efficient at flowing than more rows of smaller tubes. Partly it's a volume thing, based on total area of the tubes. Liquid flows better through a larger tube than a smaller one due to the ratio of wall area to liquid volume. Smaller tubes will be harder to push a given volume through and would result in greater pressure. I've checked with multiple BB Dart gurus, who all agree - you really want a 26" radiator. These things are not easy to keep cool. YMMV, of course.
Everything you said about tube volume and how liquid flows is a giant assumption. Greater pressures? OK, sure boss. Radiator tubes aren't round. A 1" tube isn't a diameter, it can be smashed down to 1/32" of an inch wide and it won't flow "more efficient" than a "smaller" tube. It has a longer cross section, but that doesn't necessarily mean better flow like you think.
I'm not saying the 2 core 1" radiators won't work, they will. All I'm saying is, I've seen cheap radiators work great and expensive radiators not get the job done. There's a couple of threads on this board about $700, name brand radiators not cutting it. Don't believe the manufacturer's hype on either side, because none of the websites have good scientific data. Just stuff that seems "science-y" and kinda makes sense. Well, the devil is in the details, and they don't publish those numbers. A big tube with water in the middle that isn't close enough to the tube walls to conduct heat transfer efficiently isn't an advantage. You can do larger tubes and get
less cooling if it's not done right. The radiator that flows the most water doesn’t necessarily dissipate the most heat, and that’s what you need.
A cooling system is more than a radiator too. You have to have the right water pump, pulley diameters, and thermostat too. And that's before you even get into fans. And they all have to be matched and work together. Use a really nice radiator with the wrong pump and it won't work. Use the right pump with the wrong pulley and it won't work. You get the idea, you need the components to work
together. Buying the most expensive radiator just means you spent the most money, not that you'll have the best cooling system. You have to look at everything when you ask someone about their radiator. What pump are they running, what's the pulley ratio, what fan they have, what thermostat. It all makes a difference.
