Looking at both the regular Koyo and the Koyo N-Flow radiators and I'm just wondering if theres a huge difference between the 2 or what? My stock radiator isnt cutting it anymore, for some reason my temps have been all the way up to 107ºC when driving normal in the summer so I need something better.

In the end of this project I'm looking for probably 450whp to 500whp and I auto-x it at times so does anyone think the N-Flow would be absolutely necessary? Its only about $100 more so if it would be worth it thats what I'm going with.

Also, do you guys recommend me getting new fans for the Koyo radiators?

 

N-Flow is certainly better. If you look at it the end tanks have dividers in them forcing the coolant to make an "N" flow pattern through the core and utilizing the entire core more efficiently. That said, the standard Koyo is still much better than stock.

I would probably spring for the extra 100 if you can afford it.

 

^ nice description, it just mean triple pass radiator. It makes 3 passes from inlet before it goes to outlet.

 

The regular KOYO is plenty of radiator, in fact, it's overkill. Problem with any radiator in the FD is getting enough airflow over it. An N flow isn't necessarily better or required.

If you're just now starting to have cooling issues when you previously had none, I would suggest that you replace the coolant thermostat in the filler neck. This is a common failure point that will cause the car to run hot. Get a factory one from Ray, it's only a few bucks.

 

I would go n-flow. In fact i did go n-flow. You just cant argue with a great design idea. If coolant spends more time in your radiator, then that small amount of air going through it will do more right? So then the n-flow is a better radiator. My coolant temps dont go over 82c. Do you still have your belly pan on? That makes a huge difference.

--Hank

 

OK so I'm guessing I'll go with the N-Flow radiator, its only a couple of bucks more so its no big deal. And I'm going to take speed of lights recommendation and go call Ray up and get the thermostat, its cheap and easy to change so why not?

And hsitko that 82ºC sounds beautiful. Even in 35-40ºF nights we've been having my temps always read at least 93ºC on the PowerFC. And when its hot they get all the way up to 107ºC in the summer, its just not too safe I'm guessing.

Also, anyone have any fan suggestions or will the stock fans do the job just fine?

Thanks alot to everyone for putting in some input.

 

Set your fans to 86 degrees on your PowerFC. Since you mentioned tracking the car, Look into upgrading your oil coolers. I used to get to 106-110 water temp before I bought the FDNewbie dual oil-cooler kit. Now I have a hard time even getting it to 98 (think 20 minutes of abuse). At the track water temps follow oil temps.

thewird

 

Stock fans are fine, you're really not gonna find anything better. (I measured approximately 1500cfm with the stock fans on a stock mounted rad with A/C, fans on high through the front of a '93.)


I agree with the comment about the belly pan; it's essential.

As for the N flow being a great design idea; well, I'm not so sure about that.... Its not a bad idea, but in reality, it doesn't make much, if any, difference. The coolant will spend about the same amount of time in the radiator N-flow or not.

Both of the KOYO's are overkill. Personally, I would put a slightly smaller Fluidyne (or similar radiator) in it and call it a day. The reasons are: 1) Fitment is better and it's much easier to install; and, 2) The thinner (1-3/8") radiator presents less resistance to airflow, and airflow is what you want to promote.

 

forgive me for my ignorance but what's a belly pan? I've never heard the term before now.

 

When you make that call to Ray, don't forget to get your filler neck and AST caps as well. If your feeling really motivated, get a complete set of water hoses too. I think the whole kit (hoses, caps, and thermostat) was less than $200 if I'm not mistaken. Good insurance IMO.


Some other things to consider: RE-Medy has a high flow water pump that is a worthwhile upgrade for $245, and radiatorworld.com has all aluminum 1 and 2 row radiators for considerably less than the Koyo and Fluidine sell for. Pairing them together would make for a pretty stout cooling system for a decent price. I just picked up the water pump last week, and I will be picking up a radiator from radiatorworld within the next few weeks.

BTW, The belly pan is the undertray. If it's not in place, air doesn't flow through the radiator very well and your temps will increase.

 

Undertray.

thewird

 

I figured thats what it was, just wanted to make sure.