Tubing lenght does matter! IF you use smaller ID tubing - under 10mm. I'm currently conducting some computer simulations on flow rate/pressure drop/ID/length.

So generally what kills the loop is not the blocks, rad or length - it's the ID. Don't use anything under 10mm. Another thing is the connections and splits - less = way better.

Just to give you an idea of how important the ID is:
blocks/rad: apogeegt, mcw60, heatercore (manufacturer stated or estimated pressure drop)
pump: Sicce NOVA - 1.6m H2O, 800l/hr
tubing: 8mm, 10mm, 11mm, 12mm, 13mm, 14mm (theoretically)
length: 0.95m, 1.3m, 1.9m
Simulation run with no connectors, barbs and so.

Here you go:



And with different pumps @ 0.95m tubing length:



And some calculations for the tubing only (no blocks, nothing):



Conclusions (WIP):
1. ID<10mm is an overkill!
2. ID>=13mm - enough. Bigger ID = nothing more.
3. 10mm<ID<13mm - length matters most! Every cm of it means less flow.


I will post all results soon, after a few more simulations.

ABYSS