Piston ring position

[boscoe99]

Looking at the following illustration, it appears to me as if the ring is being forced to the bottom of the ring groove by combustion gas pressure.

But I am thinking that the pressure on the top of the piston is so much greater than the pressure on the ring that the ring would be forced to the top of the ring groove. That is, the piston moves the ring downward and not the gas pressure.

Is my thinking wrong?

[walleye1]

I'd think that way too.

[fairdeal]

I've always wondered what actual evidence exists to support these kinds of "explanations"...

http://blog.wiseco.com/ring-grooves

[boscoe99]

I've always wondered what actual evidence exists to support these kinds of "explanations"...

http://blog.wiseco.com/ring-grooves

I had not heard of a "vertical" gas port to facilitate the expansion of a piston ring. Now I know.

[robert graham]

Maybe in the quest for engine efficiency and very thin/ low tension rings these ports help with ring/cylinder wall sealing...pretty neat design, although I've never seen one.

[99yam40]

seems they are talking about race or high performance motors mainly.

I guess outboard motors are high performance motors

So carboned up ring/groves cuts down on there ability to move and get shoved into the cylinder walls to seal properly.
I never realized the combustion pressure pushed the rings to seal better.

[pstephens46]

Interesting. Is this configuration generally used on all modern engines?

[robert graham]

My brother in law re-built a 351 Ford motor and installed in his Shamrock boat.....burned oil/smoked right away...rings installed upside down...with that little angle/shamfer aimed down....forced rings away from cylinder walls on the down-stroke....had to pull engine and flip the rings....all O.K. Then....live and learn I guess...

[pstephens46]

I had not heard of a "vertical" gas port to facilitate the expansion of a piston ring. Now I know.

I saw that too. In relation to drag racing. No carbon buildup to worry about. Run a few seconds and then rebuilt.