What is it physically on the outside of the engine. I did a seach but can't search for S4 or S5 cause it's under 3 letters. Motor is out on the ground. Doin't know what year it is. Whats the easiest way to tell. It's a Turbo out of a 2nd gen.

 

series 5 ... works for me in a search


i would look at the oil metering pump ...
if it has a long *** arm going to the throttle body, i would assume its a series 4
if not ... series 5

 

well you can seach for s4*and s5*

the front cover is a good way but you can't be 100 percent sure. I've switched covers before on engines.

The only true way is looking at flywheel/rotors.

98 percent of the time you can do it by visual but then you get frankenstiens out there too.

 

that is pretty much the only visual one as far as I know...OMP on S4 is mechanical, OMP on S5 is electrical...

 

Look in the exhaust ports and look at the faces of the rotors. S4 rotors are cast hand have more smooth of faces. While the S5 have vertical lines in them from milling (S5 rotors were milled, not cast), on both the faces and the compression cups.

 

The S4 knock sensor is located on the center plate under the oil filler pipe. The S5 knock sensor is located on the front rotor housing above the trailing spark plug.

 

Thats what I was looking for. I remembered reading about a sensor location but not what specific sensor or the locations. Thanks!

 

the alt harness is different and some other subtle connectors

turbos are different too (s5 manifold is straight)

spark plug gap

tid (maf sensors)

 

Hows about the lack of EGR on an S5 motor

 

vdi


edit-

-guess we're only doing turbos

 

I have an S5 ECU and harness, and it runs fine. i think the oil pump and that sensor are good ways to tell, other than ripping the whole thing apart and analyzing the pieces...

 

^ Beat me to it!

The water fill neck is plastic on the S5's, but like someone mentioned the front cover/waterpump housing can be swapped on "franken-motors".