A Koyo radiator is one of the few upgrades that fixes a problem instead of adding one. The hard part is not deciding to buy one. It is working out which part number suits your car, because the range is listed by chassis and core thickness rather than by engine.
We get this call most weeks, usually from someone whose car went off song halfway through a track day.
The short answer
- Shop by chassis code and year range. The listing title carries both, plus the part number in brackets.
- Core thickness is the second decision. The range runs 25mm, 36mm, 48mm and 53mm depending on what fits behind the bumper of that model.
- A stock power car that gets driven hard is fine on the standard thickness for its chassis. A boosted or track car should take the thickest core listed for it.
- Buy the cap at the same time. A tired factory cap undoes the whole job.
How the Koyo part numbers read
Every listing follows the same shape: model, year range, core thickness, then the part number. "Performance Koyo Radiator, Toyota Chaser, JZX100, 96/00, 48mm, (KH010860NU06)" tells you the chassis, the build years it was made for, the core and the number to quote us.
The prefix is a quick sanity check on thickness. Across the range we carry, KS parts are 25mm cores, KV are 36mm, KH are 48mm and KL are 53mm. So a KH number is a thicker core than a KV number for the same sort of car, and the KL cores are the biggest, which is why the Supra listings use them.
A few listings say "Dual Pass" in the title. Those route coolant across the core twice before it goes back to the engine, which pulls more heat out per lap. They only exist where Koyo built one for that chassis.
Picking by chassis
Nissan
The Koyo Nissan range covers most of what turns up here. The R32 GTS-T and GT-R unit is a 48mm core and it is the one that usually goes into a boosted RB. R34 GTR owners get two options split by build year, 98 to 00 and 00 to 02, both 48mm, so check the plate before you order. There is a 48mm unit for the GT and GTT R34 as well.
For Silvias, the S13 SR20DET listing is a 48mm dual pass core, and the S14 and S15 unit covers 93 to 02. The 350Z is split by engine: a 48mm core for the VQ35DE and a 36mm for the VQ35HR. R35 GTR owners are covered by a 48mm unit as well.
Toyota
The Toyota range is where the JZ cars sit. The JZX100 Chaser radiator is a 48mm core for 96 to 00 cars, and it is the one we sell most of in this group. The JZA80 Supra unit steps up to a 53mm core, as does the MA70 listing for 7MGE and 7MGTE cars.
Older Toyotas are looked after too. There is a 48mm core for the AE86 with the 4AGE, a 36mm for the SXE10 Altezza RS200 with the 3S-GE, and a shared 36mm unit that suits the 86 and the BRZ. The Hilux and 4Runner listing is a 48mm core for 84 to 95 utes.
Mitsubishi
Evo owners have four listings in the Mitsubishi range. The Evo 1 to 3 unit is a 48mm core. The 48mm core listed for 1995 to 2007 Evo 4 to 6 and 7 to 9 cars is the one to order if you have an Evo 4, 5 or 6, and there is a separate 48mm listing for the Evo 7 to 9 with the 4G63. Evo X and Ralliart Lancers run a 36mm core.
Subaru and Honda
The Subaru listings split by generation. GC8 WRX and STI cars from 94 to 00 have their own unit, the 03 to 07 WRX and STI share a 36mm core, and there are two Forester options: a 36mm covering Impreza, Outback and XV from 00 to 17, and a 36mm listed for the manual Forester XT with the 2.0L and 2.5L turbo from 04 to 08.
Honda gets the deepest model coverage in the Honda range. EG and EK Civics have separate DOHC and SOHC listings at 48mm, the B series Civic from 92 to 00 runs a 36mm, and there are 36mm units for the DC2 and DC5 Integra, the EP3 Type R, the S2000 and the FD Civic. The FK8 Type R takes a 48mm core, and there is a universal pocket radiator with a fan shroud for a car that has nothing listed.
Mazda and rotaries
The Mazda range is the one to look at for rotary cooling. The FC listings are split into an S4 48mm core and an S5 dual pass 48mm, and the FD S6 is a dual pass 48mm as well. RX8 owners choose between a 36mm, a 48mm for 09 to 11 cars, and a 36mm version with a built in auto oil cooler.
MX-5 owners are covered from the NA through to the ND, and there are listings for the Mazda 3 BK, the 3 MPS and the 6 MPS.
| If you want | Go for | Why |
|---|---|---|
| A road car that sits in traffic | The standard thickness listed for your chassis | Enough capacity without crowding the fan or the intercooler |
| A boosted street car that sees track days | The thickest core listed for your model | Extra capacity is what stops the temp climbing lap after lap |
| A drag or circuit car | A dual pass core if one exists for your chassis | Coolant crosses the core twice, so more heat comes out per pass |
| A chassis with nothing listed | The universal pocket radiator with fan shroud | Lets a fabricator build around a proper core |
What to buy with it
Get a cap. The Koyo cap listings cover the Hyper Cap SK-C13 at 1.3 bar, which fits the listed Koyo radiators, and the SK-D13 shallow plunger version in blue. A cap is cheap and a boil over is not.
While the front is apart, look at the rest of the cooling system honestly. New hoses, a clean condenser and a fan that actually pulls air are worth more than another 12mm of core. If your engine sits at high load for long periods, our electric water pump guide covers the next step after the radiator.
Where NZ Performance fits
We stock Koyo radiators in Palmerston North across the Nissan, Toyota, Mitsubishi, Subaru, Honda and Mazda listings, so most orders go out without waiting on freight. The Koyorad hub page is the quickest way to see the full range in one place. Koyorad is a Japanese manufacturer, founded in 1956 and based in Nagoya, and the fitment on these units reflects that: they are built for the chassis, not adapted to it.
If you are chasing temps on a high power street car, our reliable 1000hp street car build guide covers where cooling sits in the order of jobs. Not sure which part number matches your chassis? Send us the plate details and we will confirm it before you pay.
FAQ
How do I find the right Koyo radiator for my car?
Shop by chassis code, not by engine. Every listing names the model, the year range and the core thickness, and the part number sits at the end of the title. Match the chassis and the years first, then check the thickness suits how the car gets used.
What does 36mm or 48mm mean on a Koyo radiator?
That is the thickness of the core. In the range we stock, the KS parts are 25mm, KV are 36mm, KH are 48mm and KL are 53mm. Thicker cores hold more coolant and give more surface area, which is what a boosted or track driven car wants.
Which radiator suits a JZX100 Chaser?
The Koyo KH010860NU06 is the 48mm core listed for the JZX100 from 96 to 00. It is the usual pick for a 1JZ that sees boost or track days. Order the Hyper Cap with it so the system holds pressure properly.
Do I need a new radiator cap as well?
Yes, buy one with the radiator. The Koyo Hyper Cap SK-C13 is a 1.3 bar cap that fits the listed Koyo radiators, and the SK-D13 is the shallow plunger version. An old cap that lets go early will make a good radiator look like the problem.
Is a dual pass core worth it?
On a hard driven car, yes. Dual pass listings such as the S13 SR20DET and the RX7 FC and FD units route the coolant across the core twice instead of once. They suit track and drag use, where heat soak between runs is the real issue.
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