ok i have an 87 S4 turbo 2 and the apex seal is bad i want to know if i can swap the engine for an S5 using the S4 computer

 

dude, im in atl. just swap out the naked block. everything should be dandy form there. or just rebuild it with the s5 parts.

 

You can use the s5 block in place of the s4 block... but you'll have to swap out the front cover so your using the mechanical omp instead of the electric one from the s5. Also, when doing the swap use all your s4 manifolds and electronics so the ecu doesn't get confused.