.....I know there is a bit of turbulence exhausting from the fans which interferes with the airflow. so a small 'spacer' between the fans I believe is recommended thus the tube spacer I'm proposing to build.

It's going to be a chunky spacer but how long should I cut this thing??

Admin.... Are you able to shed any light on this considering you have testing equip and a lot more knowledge and experience. I'm a first time poster.

Anyone still watching this thread?

Hello?

I have no idea about your question mate, I'd suggest just make a new thread in the hardware section.

Generally spacers (or shrouds) are most effective at about 1 inch (25mm) depth.