Planning to preform a timing and balance belt job on a recently purchased 1991 S2. Scrolling through the catalog that I think is for the S2 and see there are two part #s listed for the timing belt (pg 60 of https://www.stuttcars.com/wp-content...-1989-1991.pdf) listed "944 105 157 04" and "944 105 323 02". Going in Pelican to order the parts and they have the prior tagged as not applicable to the 1989-1991 S2 and S models. My first guess would be the difference in single and double overhead cams. Can someone speak technically about why the belts need to be different and if there is a measureable difference? For some reason the kits for S/S2 and NA/Turbo is $150 more which seems crazy to me because how different are they? Linked both kits on pelican below.

https://www.pelicanparts.com/More_In...152-293-K1-M21
https://www.pelicanparts.com/More_In...=944M&DID=6587

 

Timing belts for the 4 valve / cylinder cars (944s, 944s2, 968) are wider than the 2 valve.

 

Thanks Gage, thats exactly the kind of answer I was looking for. Helped point me in the right direction and found some additional info on this thread...useful to any other curious soul that stumbles on this thread. https://rennlist.com/forums/924-931-...ifference.html