LongDuck

Ordered the RacingBeat KOYORAD "79-85 RX7" aluminum race radiator while it looks great, awesome welds, and is generally the right size - it still required some custom fitting to work correctly on my 84SE. Here's the file photo:

Linked: KOYO Aluminum Radiator for 83-85 RX-7 All (12A & 13B) - Racing Beat

The biggest difference is that a section of the right side mount must be cut back to clear part of the frame. It's easily done with a Dremel tool and then rounding the edges again, but otherwise would not sit down far enough without custom cutting. Also, there's no drain at the bottom, instead the bung here is for the Coolant Temp Sensor - and it's mounted further to the passenger side, requiring that you splice in a 2' section of double-strand wire in order to get your stock wiring harness to reach... The Coolant Temp Sensor also can't seat fully into the bung provided by KOYORAD because the bung is too deep, and the sensor is only about to grab about 5-6 threads, as the bung has a lip that prevents you from screwing the sensor all the way in to seat flush. Once I got the original radiator out (225k miles, and rodded-out and resealed about 3 times over the years), I saw that the leaks were due to a broken mount on the right side which allowed the radiator to slide forward slightly and contact the front sway bar. Over time, the sway bar ate it's way through the lower front fins and then caused pinhole leaks on about 4-5 of the runners. Might want to look at yours to be sure that's not happening.

As if that weren't enough, the top bung on the KOYORAD is designed the same way as the bottom Coolant Temp Bung and is a proprietary size which prevents installation of the factory Coolant Level Sensor dead-center on the top. I chose to keep the KOYORAD supplied threaded plug in there so it seals properly, and will relocate the Coolant Level Sensor into the radiator Overflow Tank - also requiring an extended single-lead bullet-connector in order to reach. Since I'm already in the habit of checking fluids EVERY TIME first thing in the morning if I'm driving it that day, this won't pose any substantial issue. Also, the radiator shroud plastic had to be clipped slightly at the top edges to allow it to come anywhere close to the metal edge of the top of the radiator. I had to add some 1/2" foam double-sided tape to the top and bottom of the shroud to get the seam filled between the shroud and the radiator, else the fan would be sucking air through that gap instead of through the radiator core... Because the aluminum radiator is about 2x as thick as the stock radiator, it means the fan blades come within an inch of the radiator surface, and I'm really hopeful the blades don't suck themselves into the back of the radiator and try to drill a hole through it under high RPM operation - but that's why it has a fan clutch (stock fan & clutch mechanism, obviously).

Overall, I'm not impressed.

It's sealed up tightly and should hold pressure, but I'm disappointed that it required this much work to be added to the car (about 6hrs of time) even though it's advertised as a 'one-size-fits SA/FB'. The sensor issue alone would be enough that I would be interested in a version that allowed me to use my stock sensors threaded into the new radiator. Time will tell to see how well this holds up,

JSmall

Have you sent an email to Racingbeat and Koyo at all? Got any pictures?

Toruki

Good write up. I had a fan beat a radiator to death once...I had a rental from Indiana and we made it to New York. The rental company was named "Rent-a-Wreck", and rightly so .

t_g_farrell

iTrader: (1)

Should have returned it to RB or called them immediately. Normally if they say it fits, it should.
It could be KOYO did some production changes that RB knows nothing about that have caused
your angst or someone shipped you the wrong product. Too late now but thats what I would
have done.

Jeff20B

iTrader: (13)

So um, I guess I don't understand why you would get a non-stock replacement rad in your oh-so stock GSL-SE. Why didn't you simply get an OE style replacement from rock auto? That's what I did. Copper and brass. Fits fine and works fine. Then again you are in the arid zone. I'm sure a stock style rad would have worked just fine for you seeing they worked fine when these cars were new. Even the crappy single cores did. All aftermarket tall style rads are dual core with the auto trans fittings.

I've never bought an aluminum and probably never will. All I read about them are problems. Some worse than others. IoTus had terrible luck with his several tries at finding something aluminum that would fit right. I told him the same thing I'm telling you.

There is no such thing as a 'one-size-fits SA/FB' when we all know (or should know) there was a big change in radiator size for the 83 model year. That line should have raised a red flag.

Would you recommend these Koyo rads to others here on this forum?

stranger

I wonder if they have an early/late production year difference as Jeff pointed out with the change. The ones on eBay tend to specify up to early 83 for one model and late 83 to 85 for the others. Also being in Arizona I know that you need all the cooling you can get in 110F+ summers especially at the track.

JSmall

Jeff, the link does say 83-85 specifically. So series 3 only. It also says its made for a manual tranny?

I've seen good reviews on Champion radiators off ebay. Perfect fitment etc. Just read and make sure you buy the one that's for your car specifically. Not hard really! Just make sure you get the correct one. A quick 2 min search on google finds that

I'd still like to see pics of this radiator with the problems though

SSpyderX

iTrader: (1)

I bought one of these radiators for my 84 GSL-SE. I did notice the bottom sensor plug is a bit further away. When I test fitted the radiator in the car, I saw no issues with fitment. But I do have the RE-Speed rack and pinion so my under carriage is a bit different than stock.

However I did find one problem with the radiator. The top sensor doesn't screw in at all. I checked the sizes and its slightly too small for the sensor. I emailed RB and they are talking to Koyo about it. Have not heard anything yet. Hope to hear soon.

LongDuck

There are 2 sensors on the Radiator, the lower coolant temp sensor, which as you stated is further away from the wiring harness than stock - and as such requires a wiring extension to reach it - and the coolant level sensor which is dead center on the top of the radiator. There was no way my stock coolant level sensor was going into the bung provided by KOYORAD, so I left the KOYORAD plug in place which has a rubber washer and seals tightly. For the coolant level sensor to work, I extended the wiring into the overflow bottle and dropped the sensor down into the bottle into the overflow coolant. As the overflow bottle is plastic (*and the radiator where it belongs is metal and grounded...), I also had to create a ground by using a section of wire coat hanger bent from the closest bolt and then inserted down into the overflow bottle. This provides the necessary circuit for the coolant level sensor to get a reading - and to turn off the dash light "ADD COOLANT".

Additionally, since the coolant level is now 'sensed' from the overflow bottle, you'll have some advance warning that the coolant is getting low before the radiator itself actually gets low - as long as your overflow system is working correctly both ways (expansion and contraction).

As to the overall fit, yeah - it fits. The sensors both require some fiddling to get them to work, but the radiator is definitely keeping the engine temps lower just judging by the engine temp gauge. I'm reading lower than it ever was with the (leaking) original radiator. HTH,

chuyler1

iTrader: (1)

There's a lot of good info here, did any of this get transferred back to Racing Beat or Koyo Rad for them to make what seems to be easy improvements to the design?

After reading this, I really do wonder, why bother with something other than OE replacement? Does it at least cool better than OE?

LongDuck

Since I modified the radiator to fit my car, I didn't expect RB or Koyo would want to hear about it. A year later, and this radiator is sealed well, and definitely cools the engine better. The thermostat wasn't changed, and the dash gauge barely makes it to the first mark even in the desert climate where I live. Typically, it will stay there even in 115-118F sitting still in traffic, which is impressive.

in hindsight, it was worth a little install hassle to get this kind of cooling effect.

chuyler1

iTrader: (1)

Thanks Longduck, are you using the fan shroud and mechanical fan or did you switch to an electric fan?

LongDuck

Stock mechanical fan, 230k mile original as a matter of fact. It fits so nicely in the shroud and was what Mazda used at the time, so no need to change it if it works as intended. The factory setup has withstood the test of time as I live and drive the car in 110-115F weather pretty consistently without any problems with overheating, even with the stock radiator. I think the aluminum Koyo just builds in a wide buffer of cooling capacity which can't hurt.

I also still have my A/C installed, so there's a condensor mounted right in front of the Koyo, too. Would probably be more efficient still if I removed that.

chuyler1

iTrader: (1)

Just a follow up for me. I ordered the KoyoRad radiator from Racing Beat. No modifications were needed to install it in my '85 GSL. The factory shroud fit just fine (but I won't be using it). The water level sensor fit on top just fine. It has a drain plug. It has a spot for a sensor near the inlet neck which would have fit the thread pitch of my Temp Sensor No.2 but that sensor is supposed to be installed on the bottom. I'm not going to bother installing it since i'm upgrading to a standalone EFI that can figure out sub zero temps on its own.

So yeah, no regrets, great product, can't wait to get the car running again so I can test it out.

Richard Miller

LongDuck

Maybe Kyorad has fixed the fitment issues. On year 3 now, and still going great. Incidentally, his is he same radiator on Mariah Motorsports track car shown at SevenStock 20.

chuyler1

iTrader: (1)

Unfortunately the oops must have been at the manufacturer because that is how I unboxed it. Looks worse in the photo than it actually is though, they aren't bent enough to impede flow and I have since made a few bumps of my own. The fins are very fragile and I imagine after a few thousand miles of driving the front will end up looking the same from road debris.

With that said, if it wasn't going to get covered by a shroud, I most certainly would have returned it for another one.

cpt_gloval

iTrader: (1)

I contacted Racing Beat about fitment on a S2 style car. The answer is it is definitely not a direct fit for the under-radiator oil cooler models. Just adding in case anybody landing here from search was after this answer.

RotaryRevn

I noticed that Racing Beat shows a different part # for this radiator than everyone else. Most shops show HH063146 as the part # but Racing Beat shows HH063144. Could this be the issue? Could Racing Beat be mixed up and selling the wrong radiators?

KansasCityREPU

iTrader: (9)

"Old part HH063144 (1983-1985 Mazda RX-7 MT 1.1L (12A engine only) will be discontinued and replaced by a radiator that will fit all trims including GSL-SE 1.3L between years 83-85. With over 50 years of experience in the manufacturing of OE replacement radiators, it was only natural that we develop a lightweight, high performance radiator line. We are proud to offer our all aluminum performance radiators designed as a true drop in installation for select vehicles, utilizing the factory equipped fan shrouds without any modifications necessary."

RotaryRevn

Good find, so it sounds like Racing Beat is selling the older style radiators (unless they have since switched to the new version but failed to update the part # on their site).

82transam

iTrader: (18)

I didn't get mine from RB so can't comment on whether they are selling the revised one or not, but I can say that the Koyo I got last summer fit with no issues at all, and has a drain etc. Very happy with it overall, sounds like the initial ones had issues - glad they fixed it!

RotaryRevn

Very clean fan shroud! Did you make that yourself, or have a local shop make it?

chuyler1

iTrader: (1)

The shroud is made by Derale and comes with the fan and fan controller. There should be a part number in my build thread (link in signature). I had to make some minor modifications to get it to fit, nothing crazy, just shaving off a bit of material and I cut my own brackets from some aluminum L-bars. I can report that the temp doesn't budge after an hour of tuning on the dyno (no fan blowing at the front of the car, just fans sucking air from behind) and it has performed well in traffic on hot days and several track days. Higher output alternator from stock is strongly recommended. I have an 80a FC alternator and even that is barely enough to run the fan, lights, wipers, and HVAC blower at idle.

RotaryRevn

Thanks for that info! I will look into Derale once I start tinkering with my car again if I can't get the cooling sorted out better. I noticed quite a few of those Koyo Radiators at Sevenstock. Honestly my car has been sitting for about 8 years but I'm starting to get my drive back to work on it. I stopped by Sevenstock this year to try and re-kindle my interest to get working on it again. (haven't been to Sevenstock for many years). If I remember correctly, my temps were running a little high during summer when I was driving my car. I also still have my AC installed.... so an AC condenser.... and intercooler in front of my radiator. A friend of mine suggested I try leaving the AC in since it was still charged and functional so I said why not. If I feel I need the extra airflow after I try everything else, then I will yank it. Also, as you can see, I have no fan shroud on my radiator (I don't really know what I was thinking when I was putting it together like that). It is a Griffen radiator that I had someone weld brackets to so that it would bolt in, that's all I remember about my radiator. The sad thing is, the car has kind of been out of sight, out of mind for so long, I forget what I did to make it all work.....LOL... but I did do most everything myself except for the wiring of the Microtech and some of the other wiring issues which a friend did for me. The microtech is still running a base map and needs to be dyno tuned. My is alternator is the one that came with this motor (which was an import motor) so I assume it will be good enough to run everything. I don't recall any hints of the alternator being too weak.