so lemme run down my latest plan for the longevity of my car:

s5 shortblock with blocked off OMP, or s4 cover, and functional s5 intake system run by s4 peripherals. sure it wont be an s5, but it should be damn close!!

this would work right? do i need to change flywheel?

 

You're going to need something to work the VDI & Aux ports.

 

Use the S4 front cover and keep everything else S5, you won't need to change anything. The flywheel and front counter weight is matched to the S5 rotors inside the engine.

With the S5 block, you'll need to use an S5 intake if emissions are required. The S4 intake has different locations for the port air...

Other than that? It's plug and play, but you just have to match everything up. Try to get as much of the S5 engine as possible to make life easier: Fuel rails, vac spider, BAC, ACV, sensors. With the S4 front cover, you can use the S4 throttle body and bend the rod to the mechanical OMP. It works.

Oh, use the S4 injectors and get an RPM switch to operate the VDI.

 

the rpm switch would be my solution for vdi, but the aux ports? i spaced here.. are aux ports still backpressure activated in s5 or is it mechanical? im probably switching to full s5 intake too. i really need a new motor, but im not going to do all that work just to make my car the same power that its always been @.

 

Yes the S5 Aux ports can be activated by exhaust backpressure. This is the simplest way. Or you can hook up another VDI switch...Search for help on this.

The S5 block will make more HP than an S4 block...Lighter rotors, higher compression, lighter flywheel, VDI intake, and 8000 RPM redline. The S4 blocks generally make more torque though. Doing all this "work" will be worth it in the end.

 

How do you set aux ports to open by backpressure? S4 actuators use negative pressure to pull diaphram while s5 actuators use positive pressure to push the diaphram.