Project S2000 Part 5: Keeping it From Overheating

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The Koyo is surprisingly light.  Even though it’s much bigger than the stock radiator, its aluminum construction makes it very light.  I almost chucked it through the roof of the garage when I went to pick it up because it’s way lighter than it looks.

How much bigger?  We had pre-mixed a 4 quart (3.78 liter) bottle.  I estimate I spilled roughly a quarter of a quart during the radiator swap.  I added almost the entire bottle, so the Koyo has roughly 3 quarts larger fluid capacity than the stock radiator.  This isn’t hard to see when you put the two radiators side-by-side!

The stock radiator has a 16mm thick aluminum core with crimped on and failure prone plastic end tanks, a typical stock set up with adequate cooling capacity for normal driving.  For track driving in our hot Sothern California desert climate we had to do better than that.

The stock coolant temp sensor was swapped over to the Koyo.  A couple wraps of Teflon tape was used to ensure there were no leaks.

The Koyo radiator dwarfs the stock Honda part with a 53mm thick core; this is over 3x thicker.  The radiator is one piece and leak free, all aluminum with tig welding.  The core uses Koyo’s signature Nocolock furnace brazing method to hold it together instead of the not as heat conductive and more likely to leak epoxy that stock radiators typically use. The filler neck is beefy machined aluminum for positive cap sealing.  The radiator has an adaptor so the fan switch from an AP1 or AP2 S2000 will work.  Finally the radiator has a 1/8″ NPT fitting welded to the hot water inlet for a coolant temperature sensor if desired.

Installing the Koyo was straight-forward.  To remove the stock radiator, the air box had to be moved out of the way a bit, fans unscrewed from the radiator and upper and lower coolant hoses removed.  We removed one of the lower under trays to ease the removal of the lower coolant hose.  Putting in the Koyo is just the reverse of taking out the stock radiator.

The Koyo uses a radiator cap rated at 1.3 bar pressure versus the stock cap rated for 1.1 bar.  Increasing the pressure of the system raises the boiling point of the coolant which can improve the cooling capacity of the system.