I want to put a s4 enine into a s5 as I got a good deal on the rebuild.

I want to keep all the s5 components and use them on the s4 core.

the problem is I need to pass emissions, and if I were to take the lower s5 intake manifold and put it on the s4 block, I would have to block off the port air. Something I cannot do if I want to pass emissions.

The apparent solution is to use a s4 lower manifold, and bolt up the VDI and selenoids to it. Since I have a lower s4 manifold lying around i could do this

Will this combo work corectly? If it doesnt is there anyway to MAKE it work correctly?

 

This is a bad idea. Not only are you up for a power loss, but youll need to change your flywheel to s4. The s5 car you're putting it into still thinks it's running an engine with hicomp rotors, and is mapped differently. That in itself would be enough to hurt your emissions I would bet.

As for your actual question, the s4 and s5 intakes are NOT interhcnageable as far as lower intakes. The bolt pattern is different. Wont work, sorry. You're gonna be stuck using the entire s4 manifold setup, or using a different engine.

Note that if you do somehow use the s5 intake on the s4 block, there is a place on the rear iron that the intake will hit, where metal must be shaved off to allow the intake to bolt up without a large vacuum leak.

IF you actually try to do this I do not envy you, especially trying to pass someone's emissions test.

 

And you have to change the front covers, and you risk squishing your poor thrust bearings (I did that, god damnit that sucked) And of course, what kevin pointed out. If I remember, the oil pans used different sensors as well, but I'm not positive on that.