Is the original R1 loom wiring(5PW) ok to use to power a new larger fan? If it is, is it just a case of extending the blue wire from the relay to provide power to the fan and then earthing it?
Thanks
Adam

Thats what I've done with mine.

adrian

If you are using MNR loom aswell you can connect the black/green from the MNR loom to the R1 fan wire from the ECU. The black earth from the MNR loom is just insulated and taped up.

This way the ECU will control the fan switching rather than the sensor on the rad.