Hemi dragengine failure : please advise (pictures)

[DrillDawg]

Looking at the pics, it looks to me like normal steel pins with aluminum plugs. Just like all of the other engines of this type use.

After looking again, robert1 is correct, the pin ends appear to be contoured to the cylinder wall to control end play and may also act as support for the pin. There are no buttons ? , the aluminum is the button with a hole to keep the pin empty. How about a complete picture of the broken rod with the bearing shells that were in it ? I have not really viewed a failed pin in these pictures but I can clearly see scuffing but without some dimensions from a good pin and piston as I'm out of suggestions. Also what was the intended purpose of this engine ? blown on alcohol in a drag vehicle ? The owner/engine builder should have caught the pin clearance issue if any , Now a rough pin surface

Is it possible that they don't even know what they have or what to call what, maybe they need to hire someone who knows..

DD.

[Belgian1979]

I asked for a complete set of additional pictures of the rod big and small end, the missing bolt and the bearings (both in top and side view). I will let you guys know.

[Kevin Johnson]

I studied the pictures again and there appear to be no cooling holes in the head surface of the block. Am i seeing this right ? Would they run an engine like this without coolant ?

Ok, here is your second comment that illustrates you need to do some quick studying of some basic elements in the field. Contemplate why this makes ejected rod bearing oil and where it lands all the more important for cooling much less for (obviously) lubrication.

The production four cylinder NA Honda B18CX has twenty oil squirters; sixteen of them are the slots I mentioned.

I would be surprised if the people making a claim against your insured have not been following this very public discussion. I do not know the law in this area but my earlier comment about industrial spies was a subtle hint. Were you given a release to publish the pictures supplied to you ? Normally this type of information would be considered proprietary. Well, it sure isn't now.

Now, a blast from the past and you should think about the bearing retaining pin:

One of these things is not like the others,
One of these things just doesn't belong,
Can you tell which thing is not like the others
By the time I finish my song?

Did you guess which thing was not like the others?
Did you guess which thing just doesn't belong?
If you guessed this one is not like the others,
Then you're absolutely...right!

~~~~~~~~~~~~

People are human. Technicians are human.

There is a reason Porsche added serial numbers to the 928 rod beams and caps. They weren't used originally. There is a reason Porsche (via GKN) added a 928 and 944 logo to differentiate the already morphologically different sintered forgings. Yet, despite this, a mismatched rod and cap but with matching serial numbers STILL made it into a hand assembled production engine that survived about 100,000 miles. The only reason this was discovered was by chance: the owner took a hi-res picture of that rod; the owner did not resize the rod; that was the rod that failed; and I looked carefully at the pictures sent to me two years prior and took the time to research the manufacturing details.

I also have a picture of a beautifully polished TAG F1 rod with mismatched cap and beam.

There is all sorts of cognitive science you can read about if you're really interested in what underlies things like this.

[OldSStroker]

Outer shell is 51 HRc
Coating 47 HRc if info was correct.
Roughness of coating : Ra 0,17-024
coating adhesion HF1

Thoughts:

HRC 51 just about the low limit for the coating specified. It's also just about the highest useful hardness I would expect from a 40 point carbon NiCrMo (4340 for example).

Coating itself should be closer to HRC 74 than 47. DLC coatings are usually quoted in Hv because they are above the effective scale of HRC.The hardness of the Balinit C ranges from Hv 1000-1500 depending on application. An approximate conversion: HRC47 = approx Hv 470 Something's not right with your number. Ra 0.17 to Ra .24 micrometers (approx Ra 7-9 microinches) is WAY rougher than any DLC I've ever seen. IMO, the substrate (the hard steel) was somewhere near that roughness prior to coating. That would be a typical grind finish without any subsequent superfinishing, and the coating would mimc the original finish.

If, in fact, the coating is Ra 0.17-0.24 mu and Hv 1500, it makes a very good round file, most especially when working against aluminum.

IMO, the coating isn't anywhere near the root cause if the pin is of the design and mass you described. Others have expounded on the pin design.

My $.02

Jon

[Kevin Johnson]

Outer shell is 51 HRc
Coating 47 HRc if info was correct.
Roughness of coating : Ra 0,17-024
coating adhesion HF1

Thoughts:

HRC 51 just about the low limit for the coating specified. It's also just about the highest useful hardness I would expect from a 40 point carbon NiCrMo (4340 for example).

Coating itself should be closer to HRC 74 than 47. DLC coatings are usually quoted in Hv because they are above the effective scale of HRC.The hardness of the Balinit C ranges from Hv 1000-1500 depending on application. An approximate conversion: HRC47 = approx Hv 470 Something's not right with your number. Ra 0.17 to Ra .24 micrometers (approx Ra 7-9 microinches) is WAY rougher than any DLC I've ever seen. IMO, the substrate (the hard steel) was somewhere near that roughness prior to coating. That would be a typical grind finish without any subsequent superfinishing, and the coating would mimc the original finish.

If, in fact, the coating is Ra 0.17-0.24 mu and Hv 1500, it makes a very good round file, most especially when working against aluminum.

IMO, the coating isn't anywhere near the root cause if the pin is of the design and mass you described. Others have expounded on the pin design.

My $.02

Jon

The pin may have had aberrant finishing with respect to the others. It is understood that association is not causation but there is still the missing retaining pin and unique witness mark on the fillet of the otherwise undamaged rod journal to explain -- unique wear marks not seen on the other journal fillets visible in the pictures. A good hypothesis explains all available data.

Edit: Aside -- Sometimes rods have oiling holes machined up through the beams to supply pressurized bearing oil to the pin area. I do not see evidence of that in the pictures supplied. If you do a search on Speedtalk I think you will find numerous discussions about how the fillet can impinge on a bearing and vice versa.

Here's an out: the force of the rod failing compressed the bearing in an area such that the material moved laterally and touched the fillet. I would not want people to think that I have a problem with confirmation bias. This still leaves the missing pin. An infinite number of hypotheses are available. Some address the available data better than others.

[Belgian1979]

1. Believe me they have no case in court regarding me publishing the pictures. Furthermore there is no mentioning of names.
2. I couldn't give a rats ass about them reading this thread. They already know this is a bogus case they are making and they know what is coming.
3. Kevin, i see what you mean. These type of conrods apparently have a bearing retaining pin in the bearing cap and I don't see them. Together with the witness marks...hmmm. Lets see what the pictures of the bearing and the bolt are going to bring us...if they will send them to me that is. If i got you right, the oil in this type of engine should do a lot of the cooling together with the incoming charge. If the bearing was turning, this rod journal would not have supplied enough oil to the bottom of the piston...
4. The report I have here state a hardness of 47 HRc - 74,5 HRa, Outer shell is HRc 51. Roughness of the coating would be the same as that of the base material it is applied to, and finishing would be the responsability of the end user IMO.

Excuse me if my questions sound silly, but methanol or nitromethane dragrace engines are pretty special and not my everyday subject. BTW : i talked to a reputable engine builder that did top fuelers some time back and he agreed to help me out. I gave him the pictures today so he's going to look at them today. Boy, i'm i glad i talked had him look at my old engine and i know him.

[582r10]

The thing that's interesting to me is WHY would anyone but the engine builder have to take responsibility for the engine or the engine failure. Disclaimers are usually pretty clear. My take on a disclaimer is if I don't agree to it then I shouldn't be using that part or service in my engine. I don't see a fault here, it blew up, shit happens, pay the price to play the game or quit. I've been in business since 1974 and I have never been sued, not once.




Roger
582r10

[hondo]

certainly cant be a nitro or methanol engine useing a .100-.125? wall toolsteel? wristpin,,,,, and as clean as the chamber & piston dome are of gasoline combustion residue & heat, this doesnt appear to have run much more then a few minutes,, without more pictures, im lookin at failure of connecting rod small end due to seizeing of wristpin to rod & piston,,,,then poof,,,,,, just a guess,,

[Kevin Johnson]

1. Believe me they have no case in court regarding me publishing the pictures. Furthermore there is no mentioning of names.
2. I couldn't give a rats ass about them reading this thread. They already know this is a bogus case they are making and they know what is coming.
3. Kevin, i see what you mean. These type of conrods apparently have a bearing retaining pin in the bearing cap and I don't see them. Together with the witness marks...hmmm. Lets see what the pictures of the bearing and the bolt are going to bring us...if they will send them to me that is. If i got you right, the oil in this type of engine should do a lot of the cooling together with the incoming charge. If the bearing was turning, this rod journal would not have supplied enough oil to the bottom of the piston...
4. The report I have here state a hardness of 47 HRc - 74,5 HRa, Outer shell is HRc 51. Roughness of the coating would be the same as that of the base material it is applied to, and finishing would be the responsability of the end user IMO.

Excuse me if my questions sound silly, but methanol or nitromethane dragrace engines are pretty special and not my everyday subject. BTW : i talked to a reputable engine builder that did top fuelers some time back and he agreed to help me out. I gave him the pictures today so he's going to look at them today. Boy, i'm i glad i talked had him look at my old engine and i know him.

Very good move to get an expert. Ruminations on Speedtalk can be helpful but you need someone at hand who can see through doubletalk immediately if you end up in court or with an arbitrator.

The shadow or darkness of the hole in the lower bearings of the assembled rods to either side of the piston is ambiguous. It could indicate the top of the retaining pin or it could be an unfilled hole. Either circumstance supports your position by slightly varied argument.

[Kevin Johnson]

Anyone wanting to push the frontier of composite gudgeon pin design might be interested in reading about hoop stresses in engineering. My suspicion is that a lot more is known in the field than you will find casually available. Some, I think, would be under intellectual munitions restrictions. Seems pretty obvious, that.

[Belgian1979]

Kevin,

I also see a shadow on the rod on the right of the piston. It looks as if this rod is enlarged somehow. I tried to magnify the picture but it gets to blury to make anything of it. Could be that the bearing shifted to the side somewhat.

[Unkl Ian]

How well do these types of coating survive on components that flex considerably ?

[DrillDawg]

In this picture the hole (if you blow it up) is damaged, elongated, like the pin has been ripped out. To me the rod shows no sign of a spun bearing, only damage from being ripped apart.

DD

[OldSStroker]

How well do these types of coating survive on components that flex considerably ?

It depends on which coating is used. The coating mentioned by the OP is for relatively hard base materials which are not expected to deflect. A different coating (Balinit® C Star, for example) is designed for softer, more deformable base materials.

My take is that relatively flexible base materials would be a problem for most of these coatings.

Jon

[Unkl Ian]

I'm assuming the wrist pin bore is a single dia straight through, like any other motor.
Yes, assumptions are dangerous.

Now check the pattern in the middle of the pin.



It appears that metal has transferred from the rod, to the pin,
but more on the edges than in the center. How is that possible ?

Does that suggest excessive flexing of the pin ?