Hi Aaron
The exit total air must always be more than the inlet. You must establish low pressure on the exit to have air flow over your coolers. Adding more and more inlets simply will not work. Air will reach a point in the cowl area while in flight that if it cant escape it simple flows around the outside of the cowl without going in.
On relatively low speed aircraft, such as Ultralight and Light Sport, the 3 to 1 rule of thumb works well. (3 out to 1 in) To test your engine a simple test can be done with an altimeter. take a spare altimeter into the cockpit with you and place the static port hose in your cowl near say the carburetor area. You can do a test on the ground but you really need to test it inflight to see what the effects are. If the altimeter agrees with your onboard one things are great. if however it reads lower your pressurising the cowl and this suggests you don't have enough outlet area.
Be very careful on where you add inlets and exists. Most aircraft will have dead zones of low pressure, such as the sides of cowls typically, that do little to help you get air in and out. The old way to check this is to use wool strings attached to the cowl and video them while in flight. Typically with a wing camera or another aircraft flying with you.
Be aware that in climb a lot of other influences come into play, such as the angle of attack in climb to your inlet ports. Most OEM will work out the correct cowl lip to direct air into the coolers in climb. You can find information online on such testing but there is no magic formula.
Cheers
