can u use a s5 rear iron and mid iron on a s4 engine?
 

I cracked my s4 rear and mid iron. so i wanted to replace them with s5 irons.. would i have to swap brackets, mani or anything.

(Assuming we are talking about NA 6 port engines)

The only functional difference on the rear iron is the temp sender for the dash temp gauge, you have to keep the larger 89-91 sensor on the rear iron.

Now the intermediate is different; it has no EGR passage or valve provision, and there is an extra exhaust air port under the intake runners. You can use it in an s4 engine BUT you have to plug the extra air port under the intake ports AND you will not be able to use your s4 EGR valve. I have done this before and simply used jb weld to pack/plug the extra exhaust air port below the intake ports.

This info is not applicable to turbo engines...

I know this post is very old but if you’re still active could you give me some insight?

can I use just an s5 center iron with all other s4 parts? And will the deletion of the egr, and blocking of the extra air port effect how the engine runs?