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Sold my Exige S
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By design, the # of fins and tubes is inversely proportional to the radiator thickness. Unfortunately, you're comparing too many variables between single and double pass radiators to be able to draw firm conclusions about heat transfer based solely on surface area.

If you want maximum radiator heat transfer, you should convert to puller fans and ditch the condenser. The factory setup yields good flow across the condenser (for better AC) at the expense of maximum radiator cooling.
 

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I can't help you with any of your questions, but I can give you this info.
Last year I changed my stock radiator to the Pro Alloy one from Boe, I had a very minor leak in the stock one. After the new radiator was installed, I did a bunch of test driving under different conditions and found there was no difference in the performance between the 2 radiators. A month or so later I changed my thermostat from the stock one to a 170 degree aftermarket one. That made a big difference, my water temp dropped on average 15 degrees, whether I was on the street or on track, so my conclusion is that the radiators, stock or aftermarket have plenty of spare capacity, the stock thermostat was what was holding back the rest of the cooling system.
 

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By design, the # of fins and tubes is inversely proportional to the radiator thickness. Unfortunately, you're comparing too many variables between single and double pass radiators to be able to draw firm conclusions about heat transfer based solely on surface area.

If you want maximum radiator heat transfer, you should convert to puller fans and ditch the condenser. The factory setup yields good flow across the condenser (for better AC) at the expense of maximum radiator cooling.
These are all single pass. Based on the data available, the relationship does not appear to be strictly inversely proportional. Should still be able to glean some idea of performance from the surface area info.

In my particular circumstance I am running a Blade 300 tune (260whp), AC and a Laminova system with a 170F thermostat. Would like enough headroom for 350whp.

I know puller fans are bout 20% more efficient than pusher fans but would like to keep the pushers for AC efficiency as the car is 90% street driven. Car needs to be capable of 30 min track sessions (M1 concourse & Waterford Hills) and back to back AutoX runs.

I question whether anything but the Denso unit would be up to the task, but am curious as to where the EP performance radiator and Koyo fall. The hope is the core specs will help shed some light on that.
 

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Discussion Starter #24
FYI - In this thread Glagola1 (post #11) claims a ~10 degree difference between OEM and the F1 Radiator. Take that with a grain of salt, probably not the most scientific study :nerd: but still good feedback.

Radiator aside there are a number of other changes you can make to increase cooling.
1. Increase system pressure - Change out the pressure cap on your header tank to increase pressure, which raises the boiling point.
2. Use less Antifreeze - Water is much more efficient at heat transfer by itself. Increasing the amount of distilled water in the system will help but needs balanced as the boiling point goes down (without a pressure increase) and your freezing point raises. You can get the same boiling point of 260F but more efficiency with 100% distilled water and water wetter @ 20psi than you can with a 50/50 mix at 12 psi. Clearly there are freezing issues here you'll have to be prepared to handle.
3. Electric Water Pump - you can program most of them to run (and the fans) after engine shutdown to continue coolant flow. Helps between AutoX runs.
4. Convert to Puller fans - As already mentioned.
5. Remove the Laminova - This may be your biggest issue as that thing is just burdening your radiator even more with the additional heat.

For what it's worth as the OP I ended up approaching this the way I kill spiders, overkill. I purchased BWR's 42mm radiator (not the F1) and did #1,2,3,4 above as well :D My logic was, similar to your issue, the lack of real data to do a comparison and I only wanted to mess this once and move on.
 

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Remember folks, when operating within the cooling limits of the Rad, the thermostat dominates. You might still see a degree or 2 difference, but where you notice the difference is when the Stat is Wide Open and the temp starts creeping above 190-200F. If you are above the heat shedding capacity of the rad a cooler thermostat does nothing(or very little).

I agree with mwhenes about pulling the laminova. Not that there isn't a place for that, but when you want to double or more the whp output and run it on the track(sustained load), adding more heat load to the existing coolant system is counter-productive. Better to run a separate side cooler for the oil.

The reason the F1 is so effective is that it has very tight tube and fin spacing. The tubes are 1/4" on center, I believe. Thus the surface area is very high. Thinner helps because as you increase the surface area you naturally restrict flow of air. Since has far less heat capacity vs water, the temp of the air as it goes through the rad is already quite high as it passes the first 37mm, there is little point to going thicker. It just adds airflow restriction with minimum cooling. The theoretically perfect radiator has the perfect balance between maximum surface area(restriction) and thickness. We've approached this the closest with the F1 rad. It supported our 380WHP Optima car very well. For most users the 42mm all-aluminum rad is a great improvement in performance vs cost.
 
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