Controlling the Heat: KoyoRad

by Frank Ewald

In the last article we discussed how HeatShield Products were being used to contain the heat. This article is looking at the installation of a Koyorad aluminum radiator. It is this author's perspective that the Koyorad radiator has long been viewed as one of the best rads available for the Nissan SR20. The installation in the NX GTi-R was quick and painless. Koyorad is a very well known radiator company that build incredible aluminum racing rads. This new rad is a key part of optimizing the cooling system.  

The Koyorad comes very well packaged with very visible fragile labels affixed to it. It arrived and was literally pristine.
Pristine may be an understatement. The polished aluminum was absolutely gorgeous to see as you pull it out of the box.
Our next article we should be able to fill in the blanks for the 2018 comparison figures. As I've been working on the articles it has caused me to wonder how effective my temperature reader will be with the reflective coating of the HeatShield products.
The Koyorad. It is long been my plan to have and install a Koyo radiator. When it arrived and I opened the box, it was even more impressive than I had imagined. The mirror finish on the Koyorad literally sparkled in the sunlight. I was also suprised by the light weight as I removed it from the very effective packaging. While working on this project in the warming spring, my garage door was open and I had a few neighbours pop in to see what was taking place. Without exception, they all commented on the Koyorad. It is literally eye catching.
My old rad, which thanks to Craigslist has now gone to help out in another SR project, was also an aluminum rad and we have gone through a lot together. It was first used with the NX's 1.6 litre engine. Then it underwent some modification to suit the SR20DET swap. This included larger inlet and outlet pipes, drilling the end tank for a water sensor bung, and eventually moving the rad cap to the centre of the rad to provide greater room for the intercooler hot side piping then in use. With the revised hot side piping that AES Auto set up for me last year, the way was cleared to install a Koyorad. This rad is built to Nissan fitment specifications but which has vastly superior cooling capabilities to the stock system. And superior cooling versus many, if not all, competitors' radiators.


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Wednesday, May 30, 2018 3:34 PM
My friend has a Koyorad radiator on his S2000, and that little bung at the top starts to foam coolant under high temps. No biggie, not a huge loss, but should he be concerned in the long run?
Thursday, May 31, 2018 5:20 AM
To get good readings from a non-contact thermometer, you will need to paint a small area with flat black paint. The reflective surface will provide false readings. Spray paint or paint marker works well.
Thursday, May 31, 2018 5:29 AM
Also, make sure you know what size area you are measuring over. The farther from the object, the larger the area that you are obtaining readings from. The laser pointer is just a guide.
Thursday, May 31, 2018 6:56 AM
Matt, I'm not sure I understand. The bung that should be attached to the overflow tank? Does he not have it connected?

Solovee2, good points and I missed out on the black paint. My measurements were taken from approximately the same distance so that should not be a major distortion. But very valid points that I cannot replicate now.

My readers have heard me say before that I'm one of the least technical writers at MotoIQ. I'm neither an engineer nor a mechanic - just a guy who really enjoys cars! Especially my own. And then hopes my readers will appreciate that as I write about my experiences.
Thursday, May 31, 2018 12:46 PM
nissannx, it's the little one to the left (pic 4) that has a plug inside it, might be for installing a sensor to read coolant temps.
Thursday, May 31, 2018 7:09 PM
Matt, the one on your friend's S2K must be different than mine. The only openings are the rad inlet/outlet, the rad filler tube/cap, the overflow tube, and the drain plug. Everything else is a threaded bung for fans or something similar. I'm afraid I cannot answer your question.
Thursday, May 31, 2018 7:09 PM
That is, his S2K rad must be different than my SR20DET rad.
Friday, June 01, 2018 1:16 PM
@Matt, I haven't had any issues at all with the Koyo on Project S2000. Seems like maybe the bung just needs to be removed and new sealant applied?
Friday, June 01, 2018 6:53 PM
How does the koyo perform compared to a Ron Davis
Saturday, June 02, 2018 9:12 PM
Brad, I'm afraid that is outside my knowledge base. Maybe someone else will be able to share a comparison.
Sunday, June 03, 2018 5:48 PM
I have been very satisfied with the Koyo in my Integra. I can run track days without ever having the needle go past the middle of the range. Its darn near twice the size of my OEM radiator.
Monday, June 04, 2018 11:16 AM
not that I'm saying the Koyo isn't doing its job, but the "without ever having the needle go past the middle of the range" doesn't mean anything. the stock gauge is a 3 position gauge; cold, operating temp (usually a really wide range), and overheated. by the time you see the needle go past the middle, its too late, your engine is too hot. I mean you engine isn't gonna blow up if you go over it once, but doing it constantly or being in the upper range of what the oem gauge considers to be ok can substantially shorten your engine life.
Mike Kojima
Mike Kojimalink
Tuesday, June 05, 2018 12:19 AM
From racing an NX2K in IMSA many years ago, I can tell you that they are very hard to keep cool compared to a B13 or B14 Sentra, probably due to the aerodynamics and limited grill opening. It is interesting that Frank has been able to keep temperatures reasonable with a turbo engine under racing conditions.
Tuesday, June 05, 2018 10:16 AM
@nissannx, @spdracerut - thanks for your input! Unless it starts spraying coolant on the engine I don't think it's an issue.
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