Iv just put an frst efi engine in my rs1600i shell and was wonder what radiator to use s1or s2? What's the diference In the two?

Thanks

 

Series 2 rad has a provision for a water return from the turbo, series 1 does not as the turbo on a series1 doesnt have a water supply! So if your running a water cooled turbo the series 2 rad is preferable, altho not 100% nessacery as there are other options avail.

 

https://passionford.com/forum/ford-r...-radiator.html

might help