Hose size / reducer positions on water / air intercooler system
 

Right, I am upgrading a few parts on my water air intercooler on my NB.

Basically I'm installing a larger heat exchanger - a rad from a fiat 500 with inlet / outlet diameter of 30mm. I'll use some reducers to / from this.

I have Bosch electric pump (25L/min) to do the pumping which has an inlet / outlet diameter of 19mm. There are reducers currently on the pump which reduces it from 19mm to 13mm hose.

All the hose in the system currently is 13mm.

I need to keep the inlet / outlet diameters of the pipes to / from the intercooler at 13mm as this is the diameter of the metal inlets / outlets of the intercooler. Am I better off converting most of the piping to 19mm hose and just use a reducer at the intercooler inlets / outlets to reduce it to 13mm or just use the current 13mm hose all through the system? (Even though the this 13mm hose will be increasing to 30mm at the rad inlet / reducing from 30mm at the rad outlet)

As in will the flow be the same regardless of the hose size as I have to have an inlet size of 13mm going into the intercooler barrel?

Bigger hose = more capacity = less heat soak

IIRC the only significant flow loss using a slightly larger diameter will be from hose swell if it is less reinforced.