So I'm in the market for a new radiator... Temp creeps up when I get on it hard and I am very slowly losing coolant somewhere... I think mine's original from 1986. That ****'s gotta go. Might as well upgrayedd for a double dose of cooling action.

Since the price difference between an S4 regular Koyo and an S5 "N-Flo" is negligible... (eBay actually has the "N-Flo" for two bucks cheaper!) I was considering going for the better unit.

The rub is, I don't like that long neck on the S5 where the radiator cap goes. That ****'s just asking to get broken off accidentally.



However, lookie here:
http://www.koyoradracing.com/product...700&modal=true


It looks as though they may have eliminated that neck.

Can anyone confirm this?

 

PM Dregg100 he would know. Or you could just get the S4 koyo and buy some S4 brackets.

 

S4 not available in "N-Flo"

 

s4 koyo has the long neck, s5 koyo does not have the long neck....

 

No it doesn't, there is no neck on the S4; the filler cap is located on the upper tank.

 

you've got that backwards, according to the koyo rad in my car, and the one sitting on the garage floor.

 

Why not check out the Godspeed? It is dual pass, has side tanks and is supposedly a perfect fit. It is also $200 shipped.


There is a thread around here somewhere...


Oh, here it is!

https://www.rx7club.com/showthread.p...highlight=koyo

 

um both of you are wrong, look at the nflow diagram it clearly shows the the cap on the upper tank for a s5 koyo rad (and I own one as well.....)

the s4 koyo rad has the long filler neck

http://i34.tinypic.com/2vwhj6e.jpg <--- s4 koyo rad

 

You're wrong too. I own an S4 and S5 RX-7...

The S4 OEM has the pressure cap in the water neck, and the S4 Koyo has a cap on the upper end tank as well.

The S5 has the goofy plastic filler neck that bolts to the equally stupid plastic end tank and is sealed with an o-ring, and the S5 Koyo also has the goofy filler neck but atleast its aluminum.

 

the s5 koyo nflow does not have the goofy filler neck look at the diagram for once lol! but the non nflow model does have the long filler neck (just noticed that and maybe that's where the confusion is comming from)

Alright I guess the rad in hyperteks car is a s5 non nflow rad...(or maybe a older version of the s4 koyo rad that i'm familar with)

 

YOU'RE BOTH WRONG!

Observe:



The diagram was just for demonstration purposes...
I want someone to confirm with an actual radiator.

Additionally, sometimes people change ****. Koyo coulda gone and said, "Oh ****, people keep breaking this thing off. Maybe we oughta change it and just start telling people to modify their fan shroud."

Maybe all radiators made before a certain date have the neck and all after have it removed.


Personally, I could do without a cap on the radiator all together. My cap is on the thermostat housing neck. S4 FTW.

 

Koyo change the endtanks from the top & bottom to the sides on the N-flow. I think it will actually fit in an S4 without any trouble, but I have not confirmed it yet.

http://banzai-racing.com/store/86-91_rx-7_radiator.html


S5 Koyo has long neck.



S5 N-flow does not have the long filler neck, it also has a bleeder like the S4



S4 koyo has a filler neck in the center.

 

Looking at the radiators side by side, I can tell that I really want a cross flow (End tanks on the left and right sides rather than on top and bottom.) and that I don't think the "N-Flo" by Koyo is really a triple pass like the Koyo adverts suggest, but more of a "U" shaped flow like the Godspeed unit.

It comes in on the top half of one side, cross over using the upper half, and moves down using the other side's end tank... After that, it crosses back to the original side using the bottom half and exits the original side through the bottom half of that end tank.

The "N-Flo" adverts have it making an additional pass back. It's like saying Turn 360 deg and walk away... Sounds good to idiots, but people who see **** properly know better.


For now, it's gonna boil down to what I can get cheapest, factoring in build quality and ease of installation. I'm stock NA, so any improvement in performance above a stock radiator will be adequate. I don't think the 3mm core thickness difference between the Koyo N-Flow and the Godspeed is gonna make THAT much of a difference.

So far it's lookin like GodSpeed is cheaper by $80 on eBay.

 

The S5 N-flo only has one partition making it a double pass. The generic picture is of the FD N-flo. However, Koyo does not advertise the S5 as a triple pass. The N-flo does a great job the S5 pictured above went from 90C temps with the regular Koyo and top mount IC, to 83C with the Greddy 3 Row FMIC and N-Flo.

This is Koyorad’s N-Flo Technology which allows for a double or triple pass radiator. This design cools more efficiently by allowing the coolant to remain in the radiator for a longer period of time therefore transfering more heat to the surrounding air. N-Flo Technology is available on cars that are known to have limited airflow to the radiator

Notice the weld in the side tank between the inlet and outlet



Cheapest is not best, and certainly not when you are talking about your cooling system.

 

I have the godspeed in my car, as well as other cars that see much track usage - it's great bang for your buck.

I will say this though - they are not a direct fit, and the lower coolant hose connections leave a lot to be desired: the heater hose connection is to close to the lower hose connection resulting in a less than optimal engagement.

 

Got the N-Flo in my S4. Need to mod the mounting holes on the radiator bracket a bit with S4 brackets.

 

I originally thought the Godspeed was almost identical to the Koyo N-Flo.
I just looked again. The Godspeed watermark threw me off...
I thought it had that weld, but it DOESN'T.

The Godspeed IS NOT a two pass radiator.



However if there are multiple vendors selling identical products from the same manufacturer, I will go with the cheapest vendor. Got any group buys running?

And that clinches it... I'd rather NOT have my coolant hoses pop off. The Koyo pictured above looks almost OE at the hose connections.

 

http://www.stewartcomponents.com/tec...ech_Tips_5.htm

While coolant velocity through the radiator increases, resulting in more coolant turbulance, and a higher overall radiator efficiency, coolant flow massively decreases.

The best modification to any cooling system is to increase the cooling system flow.

 

Of course the Godspeed is 2-pass. How else could it possibly work with both inlet and outlet on the same side tank?

Pele, you are spending too much time analizing pictures. If you will go ahead and browse around ebizle, you will find other pictures that show different views that clearly show the weld you are missing in your watermarked picture...

 

Godspeed radiator is a 2 pass.

 

What he said^

 

I have the same godspeed rad in my car

it looks identical to the one above

Works awesome, I don't regret getting it.

It was ~270 CAD shipped with customs etc etc to my door.

Dual pass koyo is 500$ all said and done.

Godspeeds works just as good and costs nearly half as much

 

****. this complicates things.
That's the first recommendation to NOT use a dual pass radiator.

However, I'm sure the dual pass cores are thicker than the factory single pass core, which is single pass.

Anyone have a figure on the factory core thickness?

Duly noted. Godspeed is back in the running.

Shop around more.

I dunno what the exchange rate is, but I'm seeing Godspeeds for $200 all day on eBay.

Koyo R1144N is running around $340 shipped. (Saw a couple cheaper the other day.)

 

I got the S5 N flow but have yet to install it (bought it like months ago, no time to do the install)

It has no neck.

I never had Godspeeds b4, but I like Koyo's build. (at least much better than those Autozone brand PoS Radiator that came with my S5)