Broke connecting rod?

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Baprace
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Re: Broke connecting rod?

Post by Baprace » Sat Sep 22, 2018 4:48 pm

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.

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Re: Broke connecting rod?

Post by Ericnova » Sat Sep 22, 2018 5:44 pm

Baprace wrote:
Sat Sep 22, 2018 4:48 pm
lance, I think your piston & pin (616gr) are a little too heavy for 3.750 stroke at 7200, ....
I may be just a nobody, but this statement shocks me....why are we buying super duper connecting rods if they can't handle this??

I've put 650gr w/pin pistons on stock ARP bolted Chevy Pink rods and ran then past 7600 rpm on a 3.75" stroke SBC's for years in a street/strip application....and Callies Ultra's can't handle that??!! :shock:

I'm serious, someone with more knowledge enlighten me here,.. please. I'm about to do it again with Howards rods and a 687 gr piston, pin, and ring package. 4.155" x 3.75".

Sorry for the thread hi-jack, I'll make a new thread if needed.

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Re: Broke connecting rod?

Post by Kevin Johnson » Sat Sep 22, 2018 9:07 pm

Ericnova wrote:
Sat Sep 22, 2018 5:44 pm
Baprace wrote:
Sat Sep 22, 2018 4:48 pm
lance, I think your piston & pin (616gr) are a little too heavy for 3.750 stroke at 7200, ....
I may be just a nobody, but this statement shocks me....why are we buying super duper connecting rods if they can't handle this??

I've put 650gr w/pin pistons on stock ARP bolted Chevy Pink rods and ran then past 7600 rpm on a 3.75" stroke SBC's for years in a street/strip application....and Callies Ultra's can't handle that??!! :shock:

I'm serious, someone with more knowledge enlighten me here,.. please. I'm about to do it again with Howards rods and a 687 gr piston, pin, and ring package. 4.155" x 3.75".

Sorry for the thread hi-jack, I'll make a new thread if needed.
Cue the "I-beams are better than H-beams" debate. :lol:

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Re: Broke connecting rod?

Post by pdq67 » Sat Sep 22, 2018 9:23 pm

I bought Eagle, 6.25" long "SIR", I-Beam rods, but then looked at the rating of their forged 4340(?) crank and found out that they were only rated at like 450/500 or so hp. Crank, something like 1,000hp or more! So I sent them back and ordered their 4340(?) 6.25" long I-Beam rods but then found out that they weren't selling them at that time!

Soooo I bought a set of their forged 4340(?) H-Beam 6.25" long rods instead BUT I really wanted I-Beam rods, Go figure!!

I have no clue, but personally I think that I-Beam rods are a skosh stronger than H-Beam rods if used in the same application!

How far off am I??

Please enlighten me so that I will learn something here!!

And I know this is onna those, "feelie", deals because guys tend to get excited about the comparisons between the two rod designs!

Each has their own ideas and opinions here is all..................

pdq67

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Re: Broke connecting rod?

Post by MadBill » Sat Sep 22, 2018 10:49 pm

Ericnova wrote:
Sat Sep 22, 2018 5:44 pm
...I've put 650gr w/pin pistons on stock ARP bolted Chevy Pink rods and ran then past 7600 rpm on a 3.75" stroke SBC's for years in a street/strip application....and Callies Ultra's can't handle that??!! :shock:..
On the other hand, here's a pink rod from my stock bottom end street-only '70 Z28. Let go during one of my infrequent excursions to ~ 7000 RPM. :(
.
Broken Camaro Rod 006.JPG
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Felix, qui potuit rerum cognscere causas.

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Re: Broke connecting rod?

Post by Kevin Johnson » Sat Sep 22, 2018 10:55 pm

:( One of those sad and expensive paperweights.

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Re: Broke connecting rod?

Post by lance flake » Sun Sep 23, 2018 9:47 am

I just can’t believe the rod would not be sufficient for this engine. The only options I can put faith in is faulty/bad part or something along the lines of a hydraulic situation. In all reality a basic scat/eagle rod should have lived in this engine.

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Re: Broke connecting rod?

Post by Newold1 » Sun Sep 23, 2018 9:59 am

Just for shits and giggles Lance can you post a picture of that pistons skirts and that cylinder bore? How did the rotating assembly balanceup, what crankshaft, internal balance? Unless something shows up there unusual I am still gonna say a simple part with a defect and no hydrauliced rod.

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Re: Broke connecting rod?

Post by lance flake » Sun Sep 23, 2018 10:36 am

Newold1 wrote:
Sun Sep 23, 2018 9:59 am
Just for shits and giggles Lance can you post a picture of that pistons skirts and that cylinder bore? How did the rotating assembly balanceup, what crankshaft, internal balance? Unless something shows up there unusual I am still gonna say a simple part with a defect and no hydrauliced rod.
Yes I will. Skirt and cylinder beat up from shrapnel. Callies magnum crank all balanced well. No gaulling on cylinder/piston rings still free in ring lands

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Re: Broke connecting rod?

Post by Frankshaft » Sun Sep 23, 2018 10:45 am

Rods break. All this thread is is opinions and ideas. Nothing to learn as to "why" this rod broke. It just broke. Would you think an Oliver billet rod would just break during the warm up on the first fire just cycling the throttle with no load? That's what happened to a friend of mine it snapped off just like the rod in this thread. No problem with bearings, pins, clearance etc. Rod bolts still clamped, bearing looked literally un run. Wrist pin free as a bird, Cassidium pins, pin bushing still had cross hatch in it, like it came out of the box. The rod simply just broke. Oliver said it was an internal defect. The argument was, well, then, do you really x-ray and zyglow inspect every rod? Or is that bs. Because you would have seen that no? They really had no answer. They did replace the rod though, at no cost.

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Re: Broke connecting rod?

Post by midnightbluS10 » Sun Sep 23, 2018 11:28 am

Kevin Johnson wrote:
Thu Sep 20, 2018 9:28 pm
digger wrote:
Thu Sep 20, 2018 9:14 pm
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.

And what does any of this have to do with this thread? To my untrained eye, youre just loading the thread with big words to try to show youre smarter than they are, all while saying nothing. In all of those posts, I've learned ZERO about what's going on with his rod. What I have seen is you guys having another pissing match. Come on, man. Is this what every thread is destined to turn into on here?

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Re: Broke connecting rod?

Post by Kevin Johnson » Sun Sep 23, 2018 12:04 pm

Kevin Johnson wrote:
Thu Sep 20, 2018 9:28 pm
digger wrote:
Thu Sep 20, 2018 9:14 pm
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.
midnightbluS10 wrote:
Sun Sep 23, 2018 11:28 am
And what does any of this have to do with this thread? To my untrained eye, youre just loading the thread with big words to try to show youre smarter than they are, all while saying nothing. ...
Ok, you do have an untrained eye. I am not going to apologize for spending a hell of a lot of time learning one trade that heavily involves visual perception and then spending a hell of a lot more time in graduate school studying visual perception as part of a cognitive psychology program. Cognitive psychology involves the application of scientific method. Here is the text from one course; you can purchase it and read through it just like I did: https://mitpress.mit.edu/books/vision-science

I know what photographs were published in failure analysis journals because I inhabited the fifth floor of the university library. Yes, I was one of those strange people that would wander through the science and technology sections and read texts that I did not have to just because I found it interesting. Last night I read an MIT dissertation and several other reports regarding gear design and testing and chose the NASA report to cite in the drivetrain forum.
midnightbluS10 wrote:
Sun Sep 23, 2018 11:28 am
... In all of those posts, I've learned ZERO about what's going on with his rod. What I have seen is you guys having another pissing match. Come on, man. Is this what every thread is destined to turn into on here?
Pay attention to what I wrote previously. Scientific method is important and researchers should not reject data as absurd on its face. The most important thing I learned in school is how to learn. When I don't understand big words I LOOK THEM UP. Yes, it involves effort.

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Re: Broke connecting rod?

Post by MadBill » Sun Sep 23, 2018 2:58 pm

Frankshaft wrote:
Sun Sep 23, 2018 10:45 am
...The argument was, well, then, do you really x-ray and zyglow inspect every rod? Or is that bs. Because you would have seen that no? They really had no answer. They did replace the rod though, at no cost.
Speaking of which, it would be worthwhile Magnafluxing/ X-raying the remaining rods and hardness checking them and the failed rod. For reference, in 1976 Carrillo told me they targeted RC 35-38 for their (4340) rods.
Felix, qui potuit rerum cognscere causas.

Happy is he who can discover the cause of things.

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Re: Broke connecting rod?

Post by lance flake » Sun Sep 23, 2018 7:02 pm

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Re: Broke connecting rod?

Post by MELWAY » Mon Sep 24, 2018 6:16 am

Baprace wrote:
Sat Sep 22, 2018 4:48 pm
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.

This would be a good answer to the problem to help solve it. But
I have built countless 4.0” stroke engines with similar weight Pistons that have seen a lot of 7500+ rpm with eagle scat and compstar H beam rods without a single failure..some on nitrous at over 1000hp
3370lb Sedan 9.89@136MPH 358chevN/A

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