[edcmat-l1]

I don’t see anything in his post that mentions boost. I’ll take your word for it.

First step in failure analysis, gather your facts.

First I will revise one part of my "theory". After the rod broke the piston wouldn't stop because 23lbs of boost on a 4.125" piston would be equivalent to 307lbs of force that kept pushing the piston down after the rod broke.

 

[VinnyVette9340]

Pretty sure this is a turbo motor dude.

Ok. I see nothing in Top fun’s post that mentions boost.

 

[edcmat-l1]

Starting the day still drunk from the night before isn’t a good look, FYI. Might want to consider changing your ways, it’s got you not only angry, but completely unable to think logically.

I'm not drunk. I didn't drink last night. Or the night before, or the night before that.

Keep talking shit, resident idiot.

 

[edcmat-l1]

Ok. I see nothing in Top fun’s post that mentions boost.

Dude it's in the original thread, first page.

 

[VinnyVette9340]

First step in failure analysis, gather your facts.

There’s nothing in his thread post that mentions boost punk.
This is the info provided.

“I posted some information about my engine failure in TOBT but I wanted to start a thread in the Tech Section that was focused on the failure analysis.

Engine details - 4.125" bore, 3.40" stroke SBF (363ci). Rods are Oliver "Standard Light" (5.400" length) rated at 1300hp. CP pistons are used. Cam is pretty mild, hydraulic with 242deg duration and around .587/576" lift on intake/exhaust. Springs are PAC Beehives with 216lb on seat and 455lb open.

“It appears to me the Oliver rod broke first. The piston first hit #7 intake valve and knocked the head off which was laying almost intact in the cylinder. The broken rod beat against the bottom of the block's cylinder walls and knock some sections out of that. At some point the camshaft sprocket's dowel pin, ARP retaining bolt AND chain broke while the engine was still running and the other cylinders have bent valves. I believe those components driving the camshaft broke when some of the broken rod debris got wedged between the cam and the block temporarily jamming it.

Someone has suggested that the head of the intake valve may have broken first. That caused the rod to fail when the piston came up and the broken valve head overloaded the rod when the piston came to TDC and the valve head acted as a "stop". This caused the rod to fail in compression.

I'm not convinced of what happened first but the intake valve stem missing because the valve's broken head is "stuck" close to it's normal closed position. I would think if the head broke off first, that valve stem would have gone up into the guide further than normal. In other words, if the valve head broke off the valve stem wouldn't be bent and stuck in the guide.

Anyone have any ideas/suggestions. I'd certainly like to know what happened first so I can do my best to avoid the same failure in the future.”

 

[edcmat-l1]

Minimum amount of movements? How about this.

First I will revise one part of my "theory". After the rod broke the piston wouldn't stop because 23lbs of boost on a 4.125" piston would be equivalent to 307lbs of force that kept pushing the piston down after the rod broke. Then as the remaining section of the rod came back up it would smack the bottom of the piston pushing it back up. This meant that if the intake broke after the rod broke it would have been have been hit multiple times with enough force to cause the dings we see in the piston top. Also, look at the combustion chamber. It had minimum damage and as I stated, shows no dramatic witness mark from the tons of force it would have seen had the valve being used as a "stop" would have caused.

Post #19 in its entirety.

You haven't even been here long enough to know what members have what for cars. Another shit talking newbie that don't know shit. Right there with DBT.

 

[sscamaro2485]

Just from personal experience I would guess it was a valve failure first. I have had that happen several times and the damage was similar to your pictures. The engine that had a rod failure did not damage the valvetrain. There is nothing worse than a valve head breaking off at 8500 RPM. It destroys everything in the engine.

 

[VinnyVette9340]

Post #19 in its entirety.

You haven't even been here long enough to know what members have what for cars. Another shit talking newbie that don't know shit. Right there with DBT.

I used the information HE provided punk!

Still but hurt over your drilled rotor bling? 🤣🤣🤣🤣🤣🤣

 

[Topfun99]

Perhaps you didn't read my other post??

It almost impossible to determine which came first from the pictures. The argument could be made either way. But, the continued movement of the piston, in your application, could 100% happen AFTER the rod failure.

Yes, I have done real "forensic" mechanical failure analysis and I've represented people, in court, as an expert witness.

Okay, I reviewed your other posts and misunderstood somewhat.

I am a registered Mechanical Engineer, not a backyard mechanic. I posted more pictures since you posted and that included a clear view of 2 witness marks where the piston hit the intake valve after the rod broke while the valve was still. These witness marks align perfectly with where the valve head would be if it were intact. There is no other way to explain how those marks got there otherwise. That is probably the best single piece of evidence supporting my conclusion - the rod broke first.

If you can think of any other detailed pictures that would interest you just ask. I can use my wife's phone to take them since it takes better detailed pics than mine.

 

[edcmat-l1]

Okay, I reviewed your other posts and misunderstood somewhat.

I am a registered Mechanical Engineer, not a backyard mechanic. I posted more pictures since you posted and that included a clear view of 2 witness marks where the piston hit the intake valve after the rod broke while the valve was still. These witness marks align perfectly with where the valve head would be if it were intact. There is no other way to explain how those marks got there otherwise. That is probably the best single piece of evidence supporting my conclusion - the rod broke first.

If you can think of any other detailed pictures that would interest you just ask. I can use my wife's phone to take them since it takes better detailed pics than mine.

I'm not a backyard mechanic. I'm about as close as you'll get to a mechanical engineer without the degree.

 

[edcmat-l1]

Because it's a forced induction engine, and the failure happened at higher RPM, in boost, it makes it much more difficult to ascertain exactly the chain of events.

I've seen valve heads break off on their own. I've seen them break from pistons hitting them.

To run the piston into the valve the valve would have to be hung open or the piston would have to be moving up at the wrong time. On the normal compression stroke the valve should be closing or closed as the piston approaches. If the rod is off and flopping around it would have had to upright itself enough to push on the remainder of the rod, or the wrist pin boss or something to that effect.

 

[edcmat-l1]

I used the information HE provided punk!

Still but hurt over your drilled rotor bling? 🤣🤣🤣🤣🤣🤣

Post something you built.

You talk alot of shit for being the one that's wrong here.

 

[VinnyVette9340]

That valve head was being shaken in the cylinder like a ball bearing in rattle paint can. You can’t have that much damage from multiple hits of the valve head across the entire top of the piston if the piston is disconnected from the rod. If the rod let go first one or two marks on the piston from the smack that broke the valve. No more piston action.

 

[VinnyVette9340]

Post something you built.

You remember every members ride right? Then you’ll remember the builds I have posted. Fuck off.

 

[edcmat-l1]

You remember every members ride right? Then you’ll remember the builds I have posted. Fuck off.

Haven't seen you post shit.

Sorry you're mad because I told you you were wrong.

 

[Topfun99]

Just from personal experience I would guess it was a valve failure first. I have had that happen several times and the damage was similar to your pictures. The engine that had a rod failure did not damage the valvetrain. There is nothing worse than a valve head breaking off at 8500 RPM. It destroys everything in the engine.

Perhaps you missed what I wrote in another post. The camshaft sprocket drive dowel, ARP retaining bolt AND the timing chain chain all broke before the engine stopped. Probably from a piece of the rod debris getting caught between a cam lobe and the block, I found a lobe with damage that would fit that scenario. Once the cam stopped of course some of the valves would stay open and get hit by the pistons in their respective cylinders. That accounts for the "damage" to parts of the valvetrain.

 

[VinnyVette9340]

Haven't seen you post shit.

Sorry you're mad because I told you you were wrong.

I didn’t want to be a dick about it, but you’re an arrogant punk.

You want to see em go dig for them.

 

[Thirdyfivepickup]

There is a decent amount of good information here... if you weed through the middle school bullshit. That's why this place sucks compared to what it was 10-15 years ago...

(or 10-15 user names ago depending on who's reading this)

 

[edcmat-l1]

I didn’t want to be a dick about it, but you’re an arrogant punk.

You want to see em go dig for them.

I am no punk. I'm probably older than you. I'm not arrogant until someone tries to tell me I'm wrong, when I'm not. You're the one that got all butt hurt when I told you that you were wrong.

I've been building cars for nearly 40 years. Some bad ass shit. I've flown around the world tuning cars. I've tuned multiple event winning race cars. Not NHRA top fuel shit, but fast 4 second 1/8 mile cars.

So yeah, when it comes to online idiots like yourself and DBT trying to tell me something I can see how I could come off as arrogant.

 

[GARYB69Z]

Regardless on what happened ..At this point its just opinion now...