Originally Posted by hotrod1994
how should i go about checking the the temp at the bottom hose on the
radiator? ir thermometer?
and the flex fan is 3-4 inches away from the radiator so ive got a felling its not getting enough air flow
1) Use a IR temperature gauge. You know, one of those with the laser dot for aiming when you pull the trigger. If you don't have one, you don't have one of the right tools to be drag racing . . You use it for everything. Engine temps, header temps to see if all cylinders are firing, track temps, tire temps, even wife temps . .
It doesn't matter how far from the radiator the fan is, if it fits in the hole in the shroud with about 3/4" all around it. The fan should also centerline or be just slightly inside the shroud. Preferably the Fan blades should be at least an inch or two (or further) from the radiator. The fan creates a vacuum in the shroud and pulls air through the radiator and the closer to the radiator it is, the less area is exposed to moving air. In other words, if you have a 17" fan and it's a quarter inch away from the Radiator, you're only using a 17" circle in your radiator to cool your engine.
On the Flex Fan. It should work just fine for the symptoms you have described. A "Flex Fan" is designed to flatten out as the fan's rpm increases and to pull LESS air as it does. At low rpm the fan's efficiency is the greatest, and the least at high rpm . . it's designed to create less parasitic drag or HP loss at higher rpms where you have moving air that takes the place of the need for a fan . .
The problem with any mechanical fan in racing applications is that they're generally riveted together and tend to come apart at really high rpms . . And if you've got an engine you're gonna buzz into the real high 6's or touch 7000 rpm plus, you should go to a constant speed electric water pump and an electric fan. It's just one thing less that's sure to fail, sooner or later . .