how do you identify if you have an S4 or S5 engine...if there's been an engine swap...

 

one way is to look for an EGR valve on top of the engine block. It's under the intake manifold though. If it has the valve or a block off plate there it's an S4, S5's did not come with EGR valves.

 

I know the compression in the s5 is a tad higher, how does this affect high horsepowered cars? Essentially I'm asking if the s5 is all that much better than the s4.

 

NA is easy. S5 has the VDI manifold.

TII is more subtle. Look for the electric metering oil pump as the biggest clue.

Also, this has been covered a lot of times. A search for "S4 S5 differences" or "identify S4 S5" will likely be a great help.

 

Yea but what if someone put the S5 VDI manifold on a S4 block? I've seen someone do that to a seven cause they couldn't get their S5 block running. Then they grabbed an S4 block just to get it running, and went through all the hassle of just getting the S5 manifold on there.

 

Dont the s5's not have maf's?!?! I thought that the s5 engine didnt have a mass airflow sensor right near the intake.I might be wrong but that would be the easiest way to check.

 

can u also tell from the 5/6th ports...don't the S4's linkage rods push in to allow more air and are activated by back pressure from the cats and S5's pull out to allow more air and are activated by the the air pump or solenoid...???

 

All 2nd gens have AFMs. However the S5 AFM is a roundish coneish device mounted blow the airbox, while the S4 AFM is a boxy silver device mounted under the airbox.

I have also added several topics that cover the differences between the S4 and S5 engine to the FAQ.

 

Yea I've actually been reading the many FAQ's in archive, but I just didn't know if there was anything that wasn't covered. I've read that the s5 t2 engine was stronger than the s4, but as to why? (Can you fill me in?) Thanks!

 

S5 blocks correct a weakness in the casting near the lower drivers side dowel on the rear plate. This has a tendency to break in high HP applications