Whoa...don't remember all those disclaimers with Fluidyne. But then that was almost 15 years ago.

 

There was a long thread about cooling efficiency of various types of radiators on this site around 2007. People talked about OE vs aluminum vs copper radiators and what construction variables and under-hood conditions made one cool better than the others. Here, IIRC, is the gist of the discussion consensus:
o Variables affecting cooling efficiency and capacity: fin design and density, fin total area, radiator thickness, radiator material
Conclusions:
o OE - very good fin density and cooling for mostly stock FD's with non-vented hoods (i.e., limited air flow through radiator, HP near stock)
o Copper radiators - mixed reviews due to low fin density, etc.
o Aluminum radiators such as the N-flow: Work very well for non-stock FD's with high HP and and non-stock IC setups, but required more air flow than stock due to lower fin density, etc.

As I said, this is from memory of the >10 year old discussion.

I just found a link to that discussion:
https://www.rx7club.com/3rd-generati...ssment-660256/

Another earlier thread on a similar subject:
https://www.rx7club.com/3rd-generati...opper+radiator

 

So basically the stock radiator will be better than the N Flo when you are sitting in traffic idlying, but if you are at WOT with turbos at 10 psi, the N Flo is probably a better choice.

I know which i would go with

 

No argument from me...
If I were doing a lot of full throttle driving such as track days, I'd agree an aluminum radiator such as the N-Flo would be more appropriate. But since I have a real race car that I actually race (F2000) and I just do full throttle bursts with the FD a small % of the time, the OE rad is likely fine for me.

 

DaveW is right on the money. Radiator fin density and thickness is the key. Race cars see higher air velocity than street car. I am replacing a knock off aluminum rad for a fluidayne 1.5 in thick and use Evan's coolant.