Part #:

Please contact us through our Contact Us page for further instructions.

N-FLO Technology?
Strategically placed aluminum partitions that are positioned in the end tanks of a radiator create a dual or triple pass configuration. With the ability to direct coolant 2 or 3 times within the radiator core, improved heat transfer and performance can be achieved within the same space. In most applications “NFLO” will be triple pass, however in some applications NFLO indicates a dual pass configuration. NFLO radiators can be identified by the “N” following the Koyorad part number.

Where can I get Koyorad Racing stickers?
Mail us a Self Addressed Stamped Envelope including paid postage on the envelope inside to receive your free Koyorad sticker pack. Sorry, no special requests or phone calls. Allow approximately two weeks for processing. USA residents only.  Mail Self Addressed Stamped Envelope to:

Koyorad Racing Dept.
15 Doppler
Irvine, CA 92618


1/8 PT Sensor Provisions?
1/8 PT sensor provisions are provided on select Koyorad radiators (supplied with matching plug) and allow most Japanese branded water temp gauge sensors (APEXi, HKS, Defi, Pivot, and GReddy) to thread directly into the top radiator tank, eliminating the need for an upper hose adapter. 1/8 PT is a Japanese standard thread pitch, also known as 1/8 BSPT, but should NOT to be confused with 1/8 NPT (Autometer style thread). 1/8 NPT threaded sensors are not compatible with 1/8 PT/BSPT Koyorad thread provisions.

Koyorad compatible 1/8 PT (1/8 BSPT) sensors:


Not Koyorad compatible w/ 1/8 NPT sensors:


Are Koyorad race radiators for Manual Transmissions only?
Yes. Though many newer vehicles are equipped with external automatic transmission coolers, unless specified, all Koyo race radiators are designed for manual transmission vehicles. If you would like to use our race radiator in your automatic transmission vehicle, you will need to install an external transmission cooler. If your automatic transmission vehicle is already equipped with an external transmission cooler, and you will be using a Koyorad racing radiator, we suggest an upgrade from a reputable source.

Some of your competitors recommend the use of their aftermarket shrouds, slim fan kits, and low temp “racing” thermostats, silicone hoses and fan switches, what does Koyorad suggest?
Koyorad recommends the use of the stock, factory equipped fan, fan shroud, thermostat, and fan switch. For proper baseline performance testing, our engineers test and develop each Koyorad radiator with the stock OE fans, shrouds, thermostat, and fan switch for a perfect fit and optimum heat transfer. If you plan on upgrading these accessories to use in addition to a Koyorad all alumunum radiator be sure to use high quality parts. Koyorad recognizes that car manufacturers take great care to design their fans to draw air through radiators at an ideal rate of speed with stock fan switches and thermostats to regulate coolant and air flow.

What type of fluid, coolant or antifreeze does Koyorad recommend?
Popular prediluted 50/50 (antifreeze/distilled water) mix is mandatory or you may use OEM manufacturer's recommended coolant.  Note:  Additional coolant additives should not be used.  Coolant additives do not contain the necessary anti-corrosion properties as popular prediluted 50/50 coolant antifreeze mix.   Dex-Cool is not to be used with Koyorad all-aluminum radiators.

Prior to radiator installation, a complete cooling system flush (including heater core flush) is mandatory in order to eliminate any old coolant, contaminants, mineral deposits, and previous additives.  Follow the vehicle's factory service manual for the proper filling procedure after a Koyorad all-aluminim radiator has been installed.  

Does Koyorad offer a high quality radiator cap for my Koyorad All Aluminum Racing Radiator?
Yes. Available separately, Koyorad offers a high quality 1.3 bar Hyper Cap (Koyo part number SK-C13) that is made in Japan. We only suggest the use of high quality pressure caps from a reputable manufacturer for optimum radiator performance.

Drain plugs?

Brand new Koyorad drain plugs (Koyo part# PI1186) can be purchased through the Koyorad retailer who sells Koyorad Race Radiators. For reference, our Koyorad drain plugs are sized M10 x P1.25. Recommended torque specification is 7-8 ft./lbs. (Note many torque wrenches do not read this low).

Post Installation Procedures
Immediately after the professional installation of your Koyo Radiator confirm with the shop attendant that:
1. Inspection for radiator hose or radiator core/tank leaks has been completed
2. Air pockets have been relieved from the cooling system
3. Factory fan(s) and fan shroud(s) have been reinstalled, plugged in and tested to be operating
4. Your cooling system was flushed and replaced with new and factory recommended coolant (If a Stop Leak type product was used previously, this must be completely flushed)


Questions regarding Koyorad products?
For pricing and availability please contact one of our authorized Koyorad dealers. For specific questions and technical assistance regarding our products we can be contacteded directly through our Contact Us page  

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