Alright all you 16V knowledgeable rennlisters, I need your help or input.
Here's a somewhat quick run-down:
Just recently I came across a big surprise in my '87 944S while replacing the head gasket. I ordered a head gasket kit for a 944S and to my surprise the head gasket from the kit was different from the gasket removed from my engine. Of course I thought the company I ordered the kit from sent me the wrong gasket set, but upon further research it was correct. Apparently, somewhere along the history of my 944S someone decided to drop a 3.0L from an '89 S2 into it. Talk about surprised and yes I checked the engine serial number to verify. The crazy part is that I've owned and have down all maintenance on this car for almost four years and even considered doing an S2 engine swap at one point.
Alright so here's my questions, other than the obvious(me not being very observant) how can one tell just by looking in the engine bay of a 944S if someone had done an S2 swap? Also, what parts are compatible from an S to an S2 engine(cylinder head, intake, etc...)? I've done a little research on-line, but haven't really found any solid info. I'm still somewhat shocked that after owning this car for as long as I have to just now find this. Any input or info. would be much appreciated. Thanks!

 

well if u have the head off, couldn't you just measure the bore?

 

That's not really what I'm after. Since it took me so long to find out that I have an S2 engine, I'd like to know what visual differences there are between the two engines(without the engine apart of course)and what parts are interchageable. Anybody Know??
Looks like the S2 only has a slightly bigger bore, it makes most of it's displacement from an increase in stroke over the S engine.

 

the intake of the s2 looks alot different than the intake of an S

 

Seems to me that the air filter is up under the nose panel on the S2. The S has it right between the nose panel and the engine.

 

Lol that is SICK. THe guy who sold it to you must've not been the guy who did and had no history on the car because any seller would've included that as a high point...

 

Wow, I dream about that kind of stuff every night. He wait a second...where'd this turbo come from?!

 

Thanks for the info. so far.
Yeah, the whole thing is kinda crazy.
I've looked at pictures of engine bays of both the S and S2's, but on my car it seems like the only thing they replaced was the long block from an S2. From what I can tell it still has the original air box and has the internal oil cooler(which I think S2's came with an external cooler). Looks like quite a few parts can swap over from an S to S2 and actually work, but I'm hoping to find out from people who have actualy done this swap what exactly works and what doesn't. Is it possible to use an S cylinder head on an S2 block?

 

From what I've read, no, it's not possible. The heads are different.
So, that means you must have an S2 head as well.

So does it have the S or S2 intake manifold?

 

I believe it has the original S intake manifold.

 

i looked through the PET parts catalogue, a quick comparison gave me the following results.

Part M44/40 (944S) / M44/41 (944S2)

Cylinder gead cover : 92810446108 / 92810446108
Camshaft intake : 94410527704 / 94410527707
Camshaft exhaust : 94410527504 / 94410527509
Oil pump : 94410701411 / 94410701411
Water pump : 94410602113 / 94410602124
Radiator : 94410603103 / 95110603103
Air cleaner : 94411001400 / 94411001601
Air flow sensor : 94460612400 / 94460612400
Throtle valve housing : 94411008301 / 94411002502
fuel collecting tube : 94411008013 / 94411008014
Intake manifold ; 94411005602(1987) / 94411003500 (1990)
Intake manifold : 94411005603 (1988) / 94411003501 (1991)
fuel pump : 94460810206 / 94460810206
fuel filter : 92811025304 / 92811025304
exhaust manifold (1-4): 94411112303 / 94411118303
exhaust manifold (2-3) : 94411118402 / 94411118402
exhaust mufler : 94411198502 / 94411198502
rear mufler : 94411104103 / 94411198502

Its not a simple answer.... some parts are the same, some not.....

 

The S and S2 heads are not interchangeable due to the differences in the water passage at the front of the head. Other than that difference, they cannot be told apart. That is why you can mount the S intake items on to an S2 head.

It is very possible you have an S2 block and head and all the bolt-on items are from an S.

Post a picture of the front-top of the engine and let's see what we have.

 

Nice, thanks for part # info.!
Looks like the S2 uses differnet cams among other things
I think you're right. I didn't think you could just swap in an S2 block and install all the S engine components back onto it and make it work, but apparently you can. I've never driven or riden in an S2 for comparison, but this car has always seemed to run well. Except for my current situation where I continue to get oil mixing in with the coolant. I've replaced the internal cooler and seals(couple of times) but continue to get the mixing. So I finally broke down and tore apart the top of the engine to take a closer look at the head gasket and head. Next step is to take the head to a engine shop to check for cracks, hopefully everything checks out okay.
I'll post pictures asap. The car is at my parents were I actually have room to work on it. Next time I'm out there, which should be this weekend, I'll snap a few pics.

 

Is your car blue? did you buy it in Xenia? I personally know of a S car from that area with a S2 motor.

Anyways,

If the head looks like that its an S2 head (Some S2 heads are smooth) but none of the S heads as far as I know are checkerboard.

 

Here's a pic of it:

It's dark blue and I bought the car from a friend of a friend in Kettering about four years ago. It's been reliable transportation up until this oil mixing with the coolant problem.
I don't recall seeing the checkerboard pattern, but I'll definitely take a closer look this weekend. Thanks!