Broke connecting rod?

[Kevin Johnson]

...

No way, the heat generated due to lack of lubrication woukd be orders of magnitude higher

Here is a nice picture of the fracture surface of a failed rod displaying straw colored heat marking. I found this pretty easily. You can argue with the owner about lighting, shading, reflection, metamerism and so forth if you like.

brokenrod2.jpg

Aside: Here is an article about the temperature inside a collapsing bubble, 20,000 degrees Kelvin or about four times that of the surface of the Sun:

https://www.sciencedaily.com/releases/2 ... 215613.htm

Science is cool.

[digger]

...

No way, the heat generated due to lack of lubrication woukd be orders of magnitude higher

Here is a nice picture of the fracture surface of a failed rod displaying straw colored heat marking. I found this pretty easily. You can argue with the owner about lighting, shading, reflection, metamerism and so forth if you like.
N








brokenrod2.jpg


Aside: Here is an article about the temperature inside a collapsing bubble, 20,000 degrees Kelvin or about four times that of the surface of the Sun:

https://www.sciencedaily.com/releases/2 ... 215613.htm

Science is cool.

Those are not heat marks more likely oily residue and dirt /grime the same stuff on his finger and thumb . A cigarette lighter flame is very hot 3500 degrees . It won't heat a rod to cherry red though unless it's a tiny fragment .....

[Newold1]

While Kevin & Digger discuss bluing and such I am going to ask Lance to clarify his last post.

Lance, are you saying the pin is now oval when viewed from the end between .003-.0038" ?

Have you rolled it on a flat surface to show a bend over its length?

[Kevin Johnson]

...

Those are not heat marks more likely oily residue and dirt /grime the same stuff on his finger and thumb . A cigarette lighter flame is very hot 3500 degrees . It won't heat a rod to cherry red though unless it's a tiny fragment .....

Wow, are you sure about that? Here is another picture of the failed rod sitting next to another rod from the same engine. Looks pretty clean to me.

Wait !!! --- I think I see some bluing next to the straw colored area in another fractured section of the rod. Down there by the big end but not very close to the bearings.

2rods.jpg

[digger]

You said you saw bluing on lances Rods to. It's probably the case of you seeing what you want aka confirmation bias. You have to be careful looking at amateur photographers internet pics.

[Kevin Johnson]

You said you saw bluing on lances Rods to. It's probably the case of you seeing what you want aka confirmation bias. You have to be careful looking at amateur photographers internet pics.

Oh gosh, there's a LOT more to it than that. Females generally have a higher cone ratio than males and so are better at determining hues. My first degree was in making porcelain teeth and these sorts of things were important. Many males are color blind in any event but that makes them better at determining value.

Most failure analysis pictures are in black and white because SEM images are gray-scale and, prior to the internet and e-publishing, glossy color plates in printed texts were very expensive.

Yeah, I took the graduate research methods courses in cognitive psych as well. There are issues beyond confirmation bias; inattentional blindness, for example.

Anyways, I have plenty of other things to do besides finding examples of fatigue failure induced coloration in broken connecting rods.

[MadBill]

...

No way, the heat generated due to lack of lubrication woukd be orders of magnitude higher

Here is a nice picture of the fracture surface of a failed rod displaying straw colored heat marking. I found this pretty easily. You can argue with the owner about lighting, shading, reflection, metamerism and so forth if you like.









brokenrod2.jpg


Aside: Here is an article about the temperature inside a collapsing bubble, 20,000 degrees Kelvin or about four times that of the surface of the Sun:

https://www.sciencedaily.com/releases/2 ... 215613.htm

Science is cool.

Let's talk about the classic beach marks and the point of crack origin under the holder's forefinger.

[swampbuggy]

Yeah Bill that pic. looks suspect....??? Mark H.

[lance flake]

While Kevin & Digger discuss bluing and such I am going to ask Lance to clarify his last post.

Lance, are you saying the pin is now oval when viewed from the end between .003-.0038" ?

Have you rolled it on a flat surface to show a bend over its length?

It is out of round. Oval shaped a bit. Doesn’t seem to be bent. If you roll it on a piece of glass it is rolls kinda oblong. Definitely not bent. Pin was tough to get out of piston and rod. The counter weight did hit the bottom of piston but I think it was after rod broke. Contact was real light

[Newold1]

Wow, that's pretty special, in most hydraulicing cases I've been a party to especially from a broken rod teardown the piston pin is bent, not ovaled. If it is substantially bent then a slight ovaling might occur but not to the range you've indicated.

Are the pins a tapered bore lightweight pin? Seen pins of that type do that. If the pin deformed before the rod bent and created some extra tension on the rod and that rod was just weaker than the rest a simple break like that might have been contributed to from the deformed pin.

I am not a big fan of thinner or tapered bore pins for just this type of reason in big horsepower or higher rpm builds.

[lance flake]

Wow, that's pretty special, in most hydraulicing cases I've been a party to especially from a broken rod teardown the piston pin is bent, not ovaled. If it is substantially bent then a slight ovaling might occur but not to the range you've indicated.

Are the pins a tapered bore lightweight pin? Seen pins of that type do that. If the pin deformed before the rod bent and created some extra tension on the rod and that rod was just weaker than the rest a simple break like that might have been contributed to from the deformed pin.

I am not a big fan of thinner or tapered bore pins for just this type of reason in big horsepower or higher rpm builds.

They are standard pins that came in wiseco lil quick 16 pistons. This engine was 700-725 hp range. All selected components should have been more than sufficent. I don't like the tapered light weight pins myself unless it is a low hp/rpm deal

[Baprace]

lance, what did the piston and pin weigh no rings? Seperate answers, thanks

[lance flake]

lance, what did the piston and pin weigh no rings? Seperate answers, thanks

I will check balance card tomorrow morning. Off memory I’m pretty sure piston was 429 grams and I’m blank on pin but I will tell you early am tomorrow

[lance flake]

lance, what did the piston and pin weigh no rings? Seperate answers, thanks

I will check balance card tomorrow morning. Off memory I’m pretty sure piston was 429 grams and I’m blank on pin but I will tell you early am tomorrow

I was wrong on piston weight. Piston is 498 grams and pin is 118 grams.

[Baprace]

lance, I think your piston & pin (616gr) are a little too heavy for 3.750 stroke at 7200, my next call would be to the con rod manufacturer and ask him what the max recomended rpm is with your piston weight. Is that piston a solid dome ? I use a con rod ( M####R ) <-name that is approx 540 gr with a 560gr pin & piston and I was advised 7600 was the maximum rpm with a 3.480 stroke.