944 S2 Engine rebuild info: Doc?
06-09-2009, 10:12 AM
#46
Rennlist Member
Yup. Sure did. WitchHunter cleaned and flow matched the injectors, and provided new rubber O-rings as well for a very reasonable price.
I would also recommend balance checking and perhaps adjusting the crank, and also weight matching the pistons, rings, rod small ends, and wrist pins. Across the 4 cylinder assemblies the balance shop got it down to 0.1g from min to max, so dead even.
The engine runs very smoothly, pulls very hard above 4K RPM, and has a very smooth and stead idle. It's just so sweet!
I would also recommend balance checking and perhaps adjusting the crank, and also weight matching the pistons, rings, rod small ends, and wrist pins. Across the 4 cylinder assemblies the balance shop got it down to 0.1g from min to max, so dead even.
The engine runs very smoothly, pulls very hard above 4K RPM, and has a very smooth and stead idle. It's just so sweet!
06-09-2009, 10:32 AM
#47
Rennlist Member
Congratulations! This was a long journey but it's great to see you finally got everything sorted out. 
Erik and Vaughan, can you please elaborate on this? I just did the belts on my S2 and am getting the same vibration but never removed the either balance shaft pulley from the shaft. Thanks!
Last update on Erik's behalf, since he was busy wrenching late last night. We tackled the 4k rpm vibration. Sure enough, as we'd all expect, the balance shafts weren't timed right. Marks lined up, but the lower shaft pulley was incorrectly installed to the shaft, leading it to be about 170 deg out of time. Recall that there are TWO keyways in the pulleys; the one marked "O" is used on the upper shaft; the unmarked one (well, supposedly according to the manual it's marked "U" but I've never seen that!) is used for alignment on the lower shaft.
06-09-2009, 12:10 PM
#48
Rennlist Member
Making Balance Shafts Correct
The best way to explain this is to show some of the Porsche Shop Manual diagrams.
The first diagram is from the Volume 1 Engine manual and is showing the orientation of the key way on the shaft when you put on the sprockets. You should note that on the upper shaft the 'O' (Oben or Up) is located on the top, while the sprocket notch is off to the right by about 30 degrees. On the lower shaft, you should note that the "O" is at the bottom, and the sprocket notch is off to the left in line with the blade projection on the back belt cover.
The second and third pictures are trying to show what it looks like before and after the lower shaft sprocket cover is installed. Note: the cover may obscure some of the stamped codes on the sprocket. Another page in the Porsche manual also states that the "U" code stamp had been dropped somewhere along the production runs.
I hope this helps make things more clear.
The first diagram is from the Volume 1 Engine manual and is showing the orientation of the key way on the shaft when you put on the sprockets. You should note that on the upper shaft the 'O' (Oben or Up) is located on the top, while the sprocket notch is off to the right by about 30 degrees. On the lower shaft, you should note that the "O" is at the bottom, and the sprocket notch is off to the left in line with the blade projection on the back belt cover.
The second and third pictures are trying to show what it looks like before and after the lower shaft sprocket cover is installed. Note: the cover may obscure some of the stamped codes on the sprocket. Another page in the Porsche manual also states that the "U" code stamp had been dropped somewhere along the production runs.
I hope this helps make things more clear.
06-09-2009, 03:10 PM
#49
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good job. so for the moment how much $$ did you sink into the rebuild? i have a perspective 89 s2 and am thinking of going with higher compression after i get myself a cat delete and possibly some headers
06-09-2009, 05:39 PM
#50
Rennlist Member
Hard to say how much money I sank into the rebuild.
As for the higher compression, the stock S2 engine is already at 10.9:1. Headers may reduce the back pressure and therefore reduce the low RPM torque, but seems like everyone's milage on this varies.
As for the higher compression, the stock S2 engine is already at 10.9:1. Headers may reduce the back pressure and therefore reduce the low RPM torque, but seems like everyone's milage on this varies.
