i just purchased a complete turbo 2 motor minus the wiring harness.

im putting it in my n/a 1987 rx7. the one problem im having is that the online shop i bought the motor from didnt know what year the motor is.

once i get the motor how can i atleast know if its an s4 or s5? is it marked on the motor or is there another way to know? if i need to buy the wiring harness my guess is that i atleast need to match that up. or will any wiring harness work regardless of year. thanks for the info.

Look at the trailing sparkplug hole if there is a threaded hole above it where the knock sensor is then it is a S5 motor. If there is no threaded hole above the trailing sparkplug hole and the knock sensor is on the center intermediate housing then you have a S4 motor. Hope this helps.

if your omp has a rod attached to it it's s4, if it has wires, it's an s5.