Do piston rings rotate on the piston?

[olddog]

Originally Posted by Barry_R

Rings rotate. Factual data is a dangerous thing. When I ran Speed-Pro we had lab data that proved it. Use radioactive pellets embedded in rings to see how fast on the dyno. Turned out to be around 10-12RPM, but completely at random - sometimes they reversed themselves.

Movement was just considered to be due to variations in bore finish and profile. A poor hone job can have deep grooves in one direction and shallow ones in the other - that'll cause the rings to spin rapidly in the grooves and they will wear out very quickly. Gaps lining up is usually bad bore profile - an irregularity in cylindrical shape.

Was the block honed by a precision machine?

10-12rpm at what condition? WOT high rpm?

Do they rotate at idle and normal driving conditions (say 2000 rpm 30 hp)?

Does the top and 2nd ring rotate the same direction and speed, thus the gaps always stay at a fixed angle from each other?

Do the oil rings rotate?

3 piece oil ring?

[Barry_R]

[quote=olddog;1095024]Was the block honed by a precision machine?
In the Sealed Power test lab - decidedly yes.

10-12rpm at what condition? WOT high rpm?
Just "in general" - they drifted around but did rotate. I don't have access to the data anymore (corporate execution) but suspect that rotation would diminish at WOT with higher pressure loading


Do they rotate at idle and normal driving conditions (say 2000 rpm 30 hp)?
Yes


Does the top and 2nd ring rotate the same direction and speed, thus the gaps always stay at a fixed angle from each other?
No - everything is independant


Do the oil rings rotate?
Don't know. Don't think they instrumented that. Might have since.
3 piece oil ring?
Yes - SS50U

[DanEC]

[quote=Barry_R;1095025]

Originally Posted by olddog

Was the block honed by a precision machine?
In the Sealed Power test lab - decidedly yes.

10-12rpm at what condition? WOT high rpm?
Just "in general" - they drifted around but did rotate. I don't have access to the data anymore (corporate execution) but suspect that rotation would diminish at WOT with higher pressure loading


Do they rotate at idle and normal driving conditions (say 2000 rpm 30 hp)?
Yes


Does the top and 2nd ring rotate the same direction and speed, thus the gaps always stay at a fixed angle from each other?
No - everything is independant


Do the oil rings rotate?
Don't know. Don't think they instrumented that. Might have since.
3 piece oil ring?
Yes - SS50U

Very interesting - it would have been interesting to have instrumented the other rings too.