Andrew, my Tornado has two with 10" propeller diameter. The engine is a std sbf 302. I have run the engine in the past but never in anger. I bought he car with the rad and fans fitted, and I believe it is std Tornado kit. I hope this helps. Other stuff to (perhaps) consider is the water flow rate and do you have any bottlenecks in the pipework, also what about the air flow in/out the front bay. Fan/temp control. K