S65 Piston Oil Squirter Redesign

[jcolley]

At risk of being flamed for causing mss hysteria:

99% of my experience is S85 with a handful of S65s. In 2009, the piston oil squirter was redesigned. This is a common part on the S65 and S85.

I have seen several S85s in of late with broken top ring lands and no other damage. Looking at the OEM piston ring end gap specs in comparison with what notable aftermarket ring companies recommend, the OEM rings are exceptionally tight. This leads me to wonder why the piston squirters were redesigned in the first place. Perhaps a better spray pattern, there is a notable difference in their design.

My theory (nothing more) is perhaps BMW set the ring gaps very tight to improve efficiency, relying on the fact that oil squirters were being incorporated to help keep piston temperatures under control. Perhaps after some time, they realized it wasn't quite optimal and refined it. A couple of people who have switched to the new style noted increased oil pressures after, possibly an indication of alteration of the spray and a smaller orifice nozzle...not my data...can't make any conclusions.

To digress a bit, on the engines I have rebuilt, I have stopped using OEM rings and switched to aftermarket (Total Seal) and follow their advice for setting ring gaps...it's nearly double that of the OEM rings. On leak down tests, compression tests, and dyno runs, I don't see any appreciable difference between the OEM and the TS rings as long as the Alusil is properly prepped for new rings. In fact, the TS rings seem to retain oil significantly better than the OEM rings.

So, the long winded question is, do any S65 owners change these out?

Do any of the dismantlers / rebuilders see the older style on the earlier motors?

Are there any examples of stock S65's popping ring lands? Oddly, on the S85, I've only seen this on the first two cylinders of either bank, so always 1,2,6, or 7.

[Green-Eggs]

Originally Posted by jcolley

At risk of being flamed for causing mss hysteria:

99% of my experience is S85 with a handful of S65s. In 2009, the piston oil squirter was redesigned. This is a common part on the S65 and S85.

I have seen several S85s in of late with broken top ring lands and no other damage. Looking at the OEM piston ring end gap specs in comparison with what notable aftermarket ring companies recommend, the OEM rings are exceptionally tight. This leads me to wonder why the piston squirters were redesigned in the first place. Perhaps a better spray pattern, there is a notable difference in their design.

My theory (nothing more) is perhaps BMW set the ring gaps very tight to improve efficiency, relying on the fact that oil squirters were being incorporated to help keep piston temperatures under control. Perhaps after some time, they realized it wasn't quite optimal and refined it. A couple of people who have switched to the new style noted increased oil pressures after, possibly an indication of alteration of the spray and a smaller orifice nozzle...not my data...can't make any conclusions.

To digress a bit, on the engines I have rebuilt, I have stopped using OEM rings and switched to aftermarket (Total Seal) and follow their advice for setting ring gaps...it's nearly double that of the OEM rings. On leak down tests, compression tests, and dyno runs, I don't see any appreciable difference between the OEM and the TS rings as long as the Alusil is properly prepped for new rings. In fact, the TS rings seem to retain oil significantly better than the OEM rings.

So, the long winded question is, do any S65 owners change these out?

Do any of the dismantlers / rebuilders see the older style on the earlier motors?

Are there any examples of stock S65's popping ring lands? Oddly, on the S85, I've only seen this on the first two cylinders of either bank, so always 1,2,6, or 7.

I thought the only different between the S85 and S65 oil squirters is the direction they squirt. S85's bend left while S65 bend right (or visa-versa). Was there more to the difference than that?

I know for the S85 stroker engines we do, we change them out to the S65 squirters so we can always order the same sets of pistons with the notch cut in the same side. That's easier than having to tell Mahle which side to cut the notch from.

[jcolley]

Originally Posted by Green-Eggs

I thought the only different between the S85 and S65 oil squirters is the direction they squirt. S85's bend left while S65 bend right (or visa-versa). Was there more to the difference than that?

I know for the S85 stroker engines we do, we change them out to the S65 squirters so we can always order the same sets of pistons with the notch cut in the same side. That's easier than having to tell Mahle which side to cut the notch from.

Looking at the part numbers, I was under the impression they were shared between the two. I guess my actual question was really did the S65 ever ship with the older design.

I have old ones galore laying around (S85) and a brand new set (revised part number) in a newly assembled motor. Will take pics of both at the shop tomorrow.