Need Help! How to calculate the air pressure drop while sizing a fan??

Hi all, I was assigned to design a liquid cooled system to cool down 18kW of power loss from an Inverter system.
I planned to use several automotive radiators connected in parallel or series to do the job, is anyone have the experience on calculating the air pressure drop when I placed a number of radiators in parallel (side-by-side) / series (back-to-back)? Also, what should I take note if I wanted to place the fan in front of the radiators (blowing) instead of putting behind it (sucking)?
Really appreciate your kind advises.

Regards,
Sean

I recommend you contact the suppliers of these units. Below is a link to a mfr website that might give you a starting point.

[URL]http://www.lytron.com/**********/Power-Generation[/URL]

Hi JAlberts,

Thanks for your comments and also the link.
I did verify with the supplier before, but they replied that they never test their radiator in parallel [COLOR=#333333](side-by-side) / series (back-to-back) which are unusual for automotive application.
[/COLOR]