I went with a single SPAL fan. The biggest I could fit was 13" (limited by the height of the radiator. You can see it here: www.the-fan-man.com/shop/size-pull-part-...-p-204.html?cPath=33 This fan pulls more CFM's than stock, and draws less amps. It's nicely made, and should be very reliable.

My stock fans melted a 25 amp relay (had one relay for each fan), nearly costing me our endurance series championship last year. The fans I had were pretty ratty, so I decided to go with a new fan, instead of buying another used set of unknown quality.

I'll post back with how it goes...

I also have a single Spal fan. I believe it is 13" which fits perfectly to the turbo radiator. It is the medium profile fan and only weighs 3 Lbs.

Thanks guys. I hadn't measured yet. I assumed the radiator was bigger than that. 13" it is. We'll have to see if I even need it.

Just got a lower 71 degree C thermostat. (Stock is 82) I'm going to drill 3 1/4" holes in the flat face of it. This will allow more water to flow to the radiator with out increasing the flow rate to the point that the water doesn't stay in the radiator long enough to cool. It's an old trick that still works well for lowering temps.

-bj

I have the turbo radiator which is taller than the N/A. The 13" fan fits right up against the fins, perfectly between the upper and lower tanks. You should measure the N/A radiator if that is what you have.

Also, if you haven't had the radiator out yet, I'll bet money it is FULL of dirt and debris from road use. You wouldn't believe what comes out of those things.

On my N/A radiator, it does not quite sit on the fins, but right on the structural surround of the radiator. This makes it sit maybe 1cm off of the fins. I have a very small shroud around the edges of the fan to keep the efficiency up.

I did not run a fan all last year. We regularly see 100+ degrees in Ca during the summer. If the system is working properly then it is a non issue. Open the hood after run sessions and it cools down plenty fast.
Saves at least 15 lbs off the front of the car. Right where you don't want it.

Of course you do have to pay attention to temps in the Pitts.

I use a stock radiator and t-stat with large oil cooler.