Thanks Powderman,
On that logic, then what is the point of watching where you put the gaps? If they are going to rotate anyway & it really is an old wives tale.
I think you might have forgotten to attach the link.
I'm not discrediting your info, because every time i've pulled the pistons out of an engine i've built, i've never bothered or remembered to check the gaps position upon removal. So i don't have the answer to it either. If i remembered to check it, then i would have the true answer, not just an internet answer.
So has anyone on this sohc forum, upon pulling out a piston(s), checked if the ring gap positions stayed the same (or roughly the same) position as to how they went in? Hondaman, Twotired, others? Surely someone has checked this in the past.
Anyone can post stuff on the internet. I like to see it for myself, or at least take it from a trusted source.
PS: Valve springs definitely rotate under high rpms and they are meant to as the harmonics are set up due to the springs and frequency, so this is true. But i'm still yet to be convinced that piston rings rotate.
The link was posted in the post before mine. Here it is again from the Institute of Diagnostic Engineers. It reads exactly as I said but I swear I had not read that link first.
http://www.diagnosticengineers.org/journal_%20articles/Ring%20Gaps%20vs%20Knowledge%20Gaps.php
It also doesn't really matter how wide the ring gap is either as long as it isn't too tight and binds when they expand. But that's another story for another thread perhaps. When rings wear and the gap gets bigger it is not the gap that allows blow by but the less tension against the cylinder wall that allows the blow by pressure into the crankcase.
Thanks Powderman,
Just read your article, it seemed alright, but i'd still love to see the video with a sight-glass mentioned my McRider.
Just reading this now
http://www.federalmogul.com/en-US/Media/Documents/ICES200976080.pdf
From what i can see, there is no mention of rotation, but they go deep into the subject of piston rings in general.
Re: The gap itself, you are right with regards to the binding. The gap will close up as the motor warms up. As the engine wears, the gap will be increased.
Some correction here:
- To say the a wide gap doesn't matter is incorrect. Look up 'gapless rings' and you will see how a wide gap reduces compression
- It is not the spring tension itself that stops 1000+ psi from getting past the rings on the power stroke. Rather, it is the pressure itself, getting behind the rings and forcing them out onto the cylinder bore. Thats what does all the sealing.
Its in the federal mogul link above.
That is not ALL that is sealing , the ring itself, as mentioned in the article, has tangential pressure against the cylinder wall. As the ring wears, the gap gets bigger but it is the loss of tangential pressure of the rings that allows the blow by. It is discussed fully in the article if you read it in it's entirety. My linked article devotes a couple of paragraphs to rings rotation. Your linked article even states that the tangential ring pressure works in conjunction with the gas pressure behind the ring. I used to run Total Seal gapless rings in my race motors but have since learned it is nothing more than a gimmick to make money by the ring makers.
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Yeah, i hear ya, but what is the ratio of tangential natural ring tension vs combustion pressure? If you get a new ring, you can squeeze it easily with your hand. How significant do you think this tension is in sealing combustion pressure at 1000+psi compared to the effect of getting the pressure behind the ring to do the real sealing?
Personally, i see a widening ring gap taking more effect on the "worn-ness" of an engine rather than natural spring tension itself. As the rings wear, the tension becomes less, but the gap also widens. The tension (being reduced due to the ring being worn) probably doesn't make that much difference because the pressure is still getting behind the ring to seal it. But because the gap is widening, you are capturing less compression, or rather allowing more to leak past & blow by.
The end gap for our engines (top and 2nd ring) as stated by the Honda manual is:
0.0079 to 0.016" (standard in spec)
0.0028" (servicable limit)
So I believe that the gaps do make a difference to the 'worn-ness' of an engine & I also believe the gap plays more of a role than the spring tension itself.
Regarding gapless rings. Your mileage may vary. Reports I've read say that unless you are running nitrous for street/strip use, you won't probably notice a difference between gapless and std rings. When you start pushing things with nitrous & increasing the pressure, then difference shows up.
