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Old 12-06-2018, 02:33 AM   #26
apachechef
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Originally Posted by MasterBlaster View Post
Uhh..... no.
Staples are more square-cornered.
This is obviously the letter "C".
Clearly you fell for it, thought I'd see if anyone would take the bait
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Old 12-06-2018, 11:30 AM   #27
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I honestly didn't hear anything. Swear to God.

Probably going to invest in a knock sensor... and muffler. I have a vibrant resonator but no muffler. Not that loud but not quiet.
I also do have a wideband that used to be on the dash but now hides in the glovebox.

The OTHER pistons look much better. One of them is fine but there's a little acne going on. Not nearly as bad as the front-most piston.

I also remember when this engine was in my other car, it once or twice 'kicked back' when under boost. Pretty aggressive kick, kinda like if you were to sidestep the gas then get back on it.

Regardless I'm going to get new pistons soon and either get a new short block or hone the walls if they look good Just was curious what everyone thought.
Did you mean to say get a knock-sense unit or a knock sensor? Any ezk116 or ezk117 should already have a knock sensor AFAIK. Might be worth checking plug gaps and heat ranges to make sure they’re all similar, as well as getting the injectors professionally flow tested.
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Old 12-06-2018, 01:56 PM   #28
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That's damage from a foreign object, not detonation.
Detonation often leads to a something being broken out of the piston (ring, land) , which will then bounce around causing similar damage.

Source: I intentionally blew up motors from detonation for research. Because college.
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Old 12-06-2018, 03:06 PM   #29
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Originally Posted by culberro View Post
That's damage from a foreign object, not detonation.
Detonation often leads to a something being broken out of the piston (ring, land) , which will then bounce around causing similar damage.

Source: I intentionally blew up motors from detonation for research. Because college.
Ah the self-proclaimed expert at blowing things up speaks.
Why no marks anywhere else if something was bouncing around?

Why clearly evidence of near-melt ?


Where is the object?
What was the object?
Why are the marks different sizes?
More than one object?
Why are the marks always the roughly same size and always around the periphery on engines from little 125s to big block Merikun V8s?

A thinking person, one who does not believe that whatever pops into their head is devinely inspired, would ponder how a tiny little pice of some foriegn object that even if it was steel, would weigh a fraction of a gram could have enough weight x speed to dent a piston crown.

A crown which sees 1100-1200 psi pressure for millions of cycles--so its kind of durable in normal circumstances...
But which at extremely elevated temps is softer than poo....and when softer than poo and subjected to gods know what for pressure during detonation, can then melt/fail whatever..

Culbertson...you need to learn you have extremely limited experience, college or not.
Your manner of always speaking/writing in absolutes shows un-sound reasoning.
Doesn't your claimed belief system warn against vanity?
Then why do you behave the way you do?
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Last edited by John V, outside agitator; 12-06-2018 at 03:12 PM..
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Old 12-06-2018, 03:37 PM   #30
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FOD!

I'd clean up any sharp burrs that stick out (if there are any), but otherwise not worry about it. Small bits of metal sticking out could get hot and encourage detonation.
bet it'd be DOD not FOD
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Old 12-06-2018, 04:31 PM   #31
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Originally Posted by John V, outside agitator View Post

Culbertson...you need to learn you have extremely limited experience, college or not.
Your manner of always speaking/writing in absolutes shows un-sound reasoning.
Doesn't your claimed belief system warn against vanity?
Then why do you behave the way you do?
Miss me? You do seem to dwell on my personal beliefs a lot, any reason for that?

You're right, I should not have used absolutes.

In my "limited" experience (over 25 piston failures in a research setting), none showed detonation marks like that. When the piston and head had marks like that, it was from a ring or a chunk of piston bouncing around.

This is what I've seen for detonation, before the piston and rings bounce through the chamber:



I'll grab some pictures of when there's marks from the rings and other piston chunks.
Here you go, you can even see the ring stuck in the top of the piston:

Last edited by culberro; 12-06-2018 at 04:37 PM..
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Old 12-06-2018, 04:54 PM   #32
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Originally Posted by culberro View Post
That's damage from a foreign object, not detonation.
Detonation often leads to a something being broken out of the piston (ring, land) , which will then bounce around causing similar damage.

Source: I intentionally blew up motors from detonation for research. Because college.
I agree. Those marks are way too sharp to be from anything other than a hard object getting smashed between the piston and head. It doesn't have enough mass to make a dent. It is the lack of clearance that resulted in those marks. I bought a 2.3 Ford TC that had plenty of marks like that in one of the forged pistons. It was clearly from a screw in that case. You could actually measure the tread pitch if you wanted to. I have a 2.3 redblock head here that looks more like this one, only, worse.
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Old 12-06-2018, 06:25 PM   #33
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Is this the last jug that gets cooled?
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Old 12-06-2018, 09:28 PM   #34
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FOD ingestion is usually isolated to one (maybe two) cylinders.

The FOD is usually unable to escape without doing damage to the valve / seat. The damage wouldn't be isolated to one side of the piston either.

But, what I really want to know is... how do you explain the erosion on the edges of the crown of the piston?

I would expect that there are trenches all the way to the ringlands.
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Old 12-06-2018, 09:35 PM   #35
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Oh yeah, it is entirely possible to have rings not broken after detonation. It is a common misconception that rings MUST be broken. Nothing is further from true.

Also, when rings are broken, they don't necessarily break away from the land. Sometimes they actually burn through.
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Old 12-06-2018, 10:09 PM   #36
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I believe the c is for the piston size.
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Old 12-06-2018, 10:42 PM   #37
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I believe the c is for the piston size.
Dude, it's for cookie... Read the comments.
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Old 12-06-2018, 11:18 PM   #38
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OP, any pics of the headgasket? Especially the portion of the gasket corresponding to the piston pics on page one?
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Old 12-06-2018, 11:36 PM   #39
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One last thing ('bout to clock in...)

Along with the erosion of the shoulder of the piston, this one particular feature is so distinctly indicative of detonation that I am surprised noone else has mentioned it yet.

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Old 12-07-2018, 12:08 AM   #40
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One last thing ('bout to clock in...)

Along with the erosion of the shoulder of the piston, this one particular feature is so distinctly indicative of detonation that I am surprised noone else has mentioned it yet.

The material redeposited on the piston crown?
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Old 12-07-2018, 12:39 AM   #41
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The material redeposited on the piston crown?
That... is a pit.
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Old 12-07-2018, 12:43 AM   #42
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I'll get some pics of the gasket tomorrow. From what I remember, the seals around the chamber were in good shape on cyl 1
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Old 12-07-2018, 03:42 AM   #43
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Originally Posted by John V, outside agitator View Post
What was the object?
I told you. It's a Cookie!

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Where is the object?
Took a bite, chewed it up, spit it out. Too stale and hard.



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Originally Posted by swedefiend View Post
FOD ingestion is usually isolated to one (maybe two) cylinders.
I believe it's spelled FOOD.

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Dude, it's for cookie... Read the comments.
Nobody reads. Too busy arguing.
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Old 12-07-2018, 05:37 AM   #44
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Old 12-07-2018, 06:28 AM   #45
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Too much focus of appearance of damage versus distribution.

Discount FOD because of impossibility of the marks being limited to one edge of a piston.

Taking the violence of the surge of intake and exhaust between the explosions of combustion, try to envison a foreign object repeatedly only damaging the same area, and not bouncing out anywhere else.

Unlikely.

to unify theories, the staple or cookie may have damaged the area in a few cycles and then was blown out, which caused hot spots that focused detonation damage in a local area.
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Old 12-07-2018, 06:47 AM   #46
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to unify theories, the staple or cookie may have damaged the area in a few cycles and then was blown out, which caused hot spots that focused detonation damage in a local area.
'C' denotes the piston diameter. Have to dig it up from a green book. Bentley manual has the chart included IIRC.

'Tis not a staple
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Old 12-07-2018, 07:15 AM   #47
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Originally Posted by swedefiend View Post
'C' denotes the piston diameter. Have to dig it up from a green book. Bentley manual has the chart included IIRC.

'Tis not a staple


I've already chided the firat person to miss the joke.
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Old 12-07-2018, 07:29 AM   #48
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Originally Posted by apachechef View Post


I've already chided the firat person to miss the joke.
Ah well, I've ignored the remark about that mark until your last post

So, nevermind
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Old 12-07-2018, 10:34 AM   #49
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That... is a pit.
Hard to tell from a 2D picture, OP are some of those bumps in the center of the piston or are they all divots?
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Old 12-07-2018, 01:31 PM   #50
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Originally Posted by apachechef View Post
Too much focus of appearance of damage versus distribution.

Discount FOD because of impossibility of the marks being limited to one edge of a piston.


Taking the violence of the surge of intake and exhaust between the explosions of combustion, try to envison a foreign object repeatedly only damaging the same area, and not bouncing out anywhere else.

Unlikely.

to unify theories, the staple or cookie may have damaged the area in a few cycles and then was blown out, which caused hot spots that focused detonation damage in a local area.
I was thinking about the distribution as well, and agree. Must have been a burnt snickerdoodle to inflict that kind of damage.
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