Engine radiator Koyo or KOYORAD

I went with a Koyo radiator, which is considerably better built than the factory piece, cost less than $300 with new hoses, and took maybe 2 hours, start to finish. Of course, I replaced the coolant at the same time.

just tested my new koyo hyper V at the track and that thing kept it rock solid cold, 180-203f the entire day but it was like 68 degrees out lol.

Koyorad if you want good OEM fitment and a fucking drain bung plus good cooling even for modified engines (we’ve put a bunch of the larger alloy ones into rx7’s)

Koyo for top quality, mishimoto for normal quality. Both will do the job well

I just bought a Koyo, goes in tomorrow and appears to be great quality

Seems like a loose ground, my s13 did this when the grounds randomly came loose. That said my s13 cluster is so damn slow to react so I run an aftermarket gauge. I have a koyo rad which came with a slot for an aftermarket sensor.

Also i would hope it's not the case, however you mentioned this after an alternator change. I had a 96 civic with a turbo setup and I had an alternator with a failed voltage regulator, all of my aftermarket gauges and temp gauge was acting like this. I would check the volts from the alternator if this is the case, it also ballooned the hell out of my battery..

im steady at 75°C (167°F) with stock Ka, koyorad radiator, fanshroud and oe/oestyled clutch fan. and iirc, a stock nissan thermostat. hottest ive seen was like 89°C (192°F) and that was sitting in traffic on a hot summer day. idk how im running so cold lol.

I went with the Koyorad on mine. Everything fit perfectly, no modifications needed, which hasn't always been the case for me

Mine developed a small slow leak out of that nub two weeks after I bought it. Koyo gave me the run around on their warranty, insisting on photos of a destroyed radiator for replacement. I gave up. It’s a shame because it fit awesome and looked great.

I recently installed a Koyo radiator in my s13 to replace the stock one that had been leaking. I bled the air thoroughly when I filled the system with a spill free funnel and the bleed screw on the water outlet. Even after doing this, my car started overheating intermittently after driving around for a bit. When I stopped, the upper hose and radiator were very hot but the lower hose was cool to the touch. I tried to bleed more air out of it with the spill free funnel, but no air came out, and the water in the funnel started getting hot and overflowing. I pulled the thermostat to verify if it's functioning properly and it is, also it's the type that will stay open in the event of failure. This might seem silly, but I feel like the thermostat is closing and opening because the radiator is cooling too well.