Which Break In Method For You?

[Dave Ritsema]

If you think about it, the ring exerts maybe 5-10 lbs of spring tension against the cylinder wall ...
How can such a small amount of spring tension seal against thousands of PSI (Pounds Per Square Inch) of combustion pressure??
Of course it can't.

I had read that article before, the author lost all credibility with me with the "Thousands of PSI " of combustion chamber pressure statement. More like 160 - 180 PSI?

[stroguy]

How much pressure is generated on the piston head upon detonation?

[willtill]

How much pressure is generated on the piston head upon detonation?

If you have detonation; you have bigger problems.

[BIGLRY]

If you think about it, the ring exerts maybe 5-10 lbs of spring tension against the cylinder wall ...
How can such a small amount of spring tension seal against thousands of PSI (Pounds Per Square Inch) of combustion pressure??
Of course it can't.

I had read that article before, the author lost all credibility with me with the "Thousands of PSI " of combustion chamber pressure statement. More like 160 - 180 PSI?

Ah contraire my friend, while it is true the compression of the cylinder may be 160 to 180 PSI when turning over an engine not running like when doing a compression check, but when an engine is running and the air & fuel mix are being detonated in a controlled explosion to make power to push the piston down the combustion pressures do rise much higher that the "160 to 180 PSI" found in a non-running engine's compression.

"Combustion / Expansion Stroke
This stroke is where the spark plug ignites the air/fuel mixture, creating very high cylinder pressure which rise very quickly. Peak cylinder pressures near TDC (where spark occurs) will be in the range of 300 psi for engine's at light loads, to 1000 psi for production engines at full power to 1500 psi or greater for race engines."
http://performancetrends.com/Definit...r-Pressure.htm

Here is a quote from http://mb-soft.com/public2/engine.html about the compression pressures on a 4" aluminum piston, the article is a long read so I only put in info pertaining to our thread.
"Since the piston is 4" in diameter, the top surface of it is just PI * (4/2)2 or around 12.6 square inches. Each of those square inches experiences the 500 PSI(G) pressure (Pascal's Law), so the total force then instantaneously applied to the top of the piston is 12.6 * 500 or around 6300 pounds. (OK. It is ACTUALLY the 515 PSIA, but there is natural air pressure pressing against the UNDERSIDE of the piston as well, so the NET effect we are interested in is due to the GAUGE pressure. Not too different, but slightly!) But those aluminum alloy pistons in your engine are pretty amazing in being subject the 6300-pound force of hundreds of explosions pounding down on them every minute!

[BIGLRY]

How much pressure is generated on the piston head upon detonation?

See post above

[BIGLRY]

If you have detonation; you have bigger problems.

Very true and why normal combustion is sometimes referred to as a 'controlled explosion' while "detonation" is an 'uncontrolled explosion' and pre detonation is an 'uncontrolled explosion' igniting the air/fuel mix before it is suppose to!

[stroguy]

Larry said contraire.

[BIGLRY]

Larry said contraire.

My bad... I should have said Au contraire instead of "Ah contraire".

[Dave Ritsema]

My bad... I should have said Au contraire instead of "Ah contraire".

LOL Good discussion.

[BIGLRY]

LOL Good discussion.