What Does the "S" Have That I don't Have?
 

I have a base model 1987 944, and I saw a 1987 944S online for pretty cheap (it has a bent valve). I was wondering if it would be worth buying for parts. I know it has a 16v motor and makes a little more power. How about the transaxle? Does it has LSD and/or shorter gears?? Does it have bigger brakes? If I wanted to rebuild that motor and put it in my 944, would it be plug and play?

Slightly different gearing and the 16v engine.. That is pretty much it. Nothing worth taking off really.

For the engine swap you would need the entire wire harness for the engine including the ignition module which is unique to the S and S2.

Is the S car that much worse off than your car that you couldnt just rebuild rebuild the S engine and keep it in the orignal car? And assume the car has bent valves. plural. Very costly. Tensioner pad.

188 hp.;)

I'm rebuilding the engine in my S car... so far, so expensive. gonna be around 200hp when finished :)

It actually doesn't look too bad, but i have an attachment to my car. haha. I was thinking about pulling out the motor and slowly rebuilding it on the side as money came in. My 944 is my daily driver, so it would be nice to build a motor at my own pace without a rush to finish.

If i wanted to put this 16 valve motor in my car, or even the 3 liter S2, would the engine harness plug right into my chassis harness? (assuming it is from the same year) and are the DME plugs the same?

No, wiring harness is not the same, there's an extra harness for the ignition igniter on the S. Depending on the mileage on that S you might be able to fix it on the cheap. Last I checked valves were only about $25 each from EBS. It's probably not more than 8 you'd have to replace, then buy a headgasket kit

Yeah, shouldn't be too major of an operation to fix the motor, unless the chain tensioner in the head went bad, since it often gets torn off it's mounts, sometimes taking a chunk of the head with it, and eats chain gear teeth off the cams, which aren't cheap and hard to find, even used.

"S" has the same brakes as an 8V. Different final drive ration than the 8V.

The S also has the Turbo's brake bias valve.
I have also heard that something is stronger in the transmission (the pinion, maybe?)

And the S has some kind of auxiliary resonator in the exhaust which makes its exhaust somehow fit differently, if you're looking at swapping parts.