docmirror

Suppose one had an S3 engine from an 86, and wanted to put it in a S4 car by moving the intake, injectors, etc over.

Any other concerns? As far as I know, the only diff is the cams, intake, inj, and fuel delivery. Everything should move over pretty well.

But I've never done it. If you have, let me know.

BC

Intake ports on s3 are completely different shape than s4

Air would be smashing into a big 1/4 lip on both sides of port on head. Also on the s3 block, there are cast walls in the V that are there for the j pipe under the (s3) intake. These would now allow the s4 j pipe.

S4 has knock sensors and you would need to change the block plugs in the V to accept the bolt that holds them there, IIRC

docmirror

Ok, didn't know the heads were so different. Scotch that idea then. Proceed on with the complete S4 engine.

BC

Don’t mean to dissuade you. It may just be more work than it worth it.

V2Rocket

this is the difference between S3 (Left) and S4 (really its a 944S head on the right but the ports are roughly the same)



to illustrate further...i made an "adapter" to use a 944S(nearly 928S4) intake gasket/manifold on a 928S3 head. 928S4 ports are the same height as 944S but a little narrower. as mentioned the S3 ports actually extend "down" (towards the center of the valley) another 1/4" or so, they are cut off by this adapter.