Here are the nuts from the #2 con rod, found lying in the oil pan. Threads were intact, they just backed right off....

 

that is....... wait for it........


NUTS....

 

Hate it when that happens to my rod nuts.

 

Yes when your nuts fall off you KNOW something has gone terribly wrong....

 

No. Bolts bent to crap, but intact as one piece.

Although the nuts were obviously bounced around and got "distorted", how do they end up off the bolts and laying in the bottom of the oil pan, in the few revolutions that occur after the thing started turning to crap....with intact threads inside?

 

I'd suspect that it was the nuts coming off the bolts that caused the incident. I don't know the history of the engine though.

 

The forces making the rod nuts to back off while preserving the threads and producing observed distortion boggle my mind. Someone please enlighten me!

 

I hope this will not lead to threats of violence against my persona, but I'll speculate anyway: I vaguely recall that one of the reasons why Porsche but the r2 bandaid on the GTS to replace the r1 rods is that the r1 rods had the nuts back off in some cases. Judging based on the minimal design changes between r1 and r2 rod, focused mostly in the big end, my guess is that something in the engine potentially resonated with the rod big end in the r1 rod. I could imagine issues like damaged crankshaft damper or maybe a problem with the thrust bearing could create the type of vibration that could resonate with the r1 rods. This is all speculation plus a vague memory, but if this engine had r1 rods and there was some other simultaneous problem that could have caused high-frequncy vibration then that would be consistent with my speculation. It would still remain just speculation.

 

That's a very good theory on what got the failure started. I think what Greg can't figure out is how the nut made it completely off the bolt. Once the nuts backed off a little bit, there should have been loss of oil pressure on that journal and a spun bearing and big end failure long before the nuts worked themselves all the way off. My limited imagination can't come up with a plausible scenario where that could happen. Only silly things, like the rod caps being welded on or something.

 

Definitely had R1 rods. AFAIK the damper was fine. Good bit of wear on the front face of the thrust bearing:



Closeup:


But the actual journal surface and the rear were ok:




#2 rod big end bits:

Interesting how the rod bolts have been tapped out of the big end of the rod by a comparable amount on each side- I've never tried to press out a rod bolt but I'd guess it takes some force to do so.

 

After thinking about how this could occur, for a couple of years, I would accept almost anything.

However....see below.

 

Exactly!

 

Actually, after contacting the previous owner and finding out that he had been playing with a vacuum pump system for the engine, I'm pretty sure that the negative crankcase vacuum sucked the nuts loose.

 

Greg,
From Joe's records the system only had a slight change for about 380 miles. Cleaning the filter in the provent from oil saturation is not a simple task. Nor is it acceptable to ask someone to have to clean that filter in less than a tank of fuel.

As to proposing to me that I use my system for a short period of time. This is a lie. You never asked me to run my system for a short period of time and then put your system back on. In fact, in the conversations you were told about the high oil consumption which returned the moment your oil lines and intake were filled with oil after cleaning them all out. Then after you stated that you were never informed that the provent had ANY oil in it and that you had not been told about the high rate of oil consumption. (I have emails to back up these statements as well.) You were however told that the majority of your system had not been removed, just capped off and left on so that we could test the difference with the vacuum pump. You however stated that your "plates" bolted to the bottom of the valve cover should remove 100% of the oil and that the provent shouldn't ever have any oil in it (again in writing I have that).

You also state that I have not done my homework on this system, yet I have.

 

To those who are interested, Joe came out yesterday and we fitted my air oil separator to his car. The one that was previously on his car was the previous prototype.

This unit will be the final (more or less), revision.
The dynamic crankcase readings are;
Hard acceleration 0-90MPH - max of 6" Hg vacuum.
Cruising at highway speed - between 2-3" Hg vacuum.
Idle - 0.5" Hg vacuum.
High RPM compression braking - 8" Hg vacuum.

We drove at a higher RPM then compression braked and saw 8" Hg vacuum, we then got back on the gas and accelerated and the vacuum dropped back down to 6" Hg in roughly 3 seconds.

This separator was designed well before this thread was even started.

Prior to putting this system on Joe's GTS I had spoken to numerous pro engine builders, Bill Dailey of Dailey engineering, and numerous other experts. All of them gave me the same information with slight differences that crankcase vacuum below 15" Hg would not be an issue. Since Greg's last batch of statements I spoke with Bill Dailey again (I haven't been able to get a hold of the others due to the weekend). Bill stated that the lack of oil scraper ring holes in the piston would have little effect as the wrist pin is splash oiled. But to regulate the vacuum to about 12-14" to be on the safe side. There is not magic number and it has to do with the ring seal. The more blowby the motor has the more exhaust gas gets sucked/pushed through the pin interface and this is what kills the pin bores.

So at a low level of vacuum, the rings will seal better, preventing less exhaust gasses past the rings, which will actually AID in the oiling to the wrist pin.

None of the research I had done before putting this system onto my own car, or subsequently Joe's car showed any of the things Greg claims (increasing bearing clearance, shortening wrist pins, etc.) were done on any of the engines currently running vacuum on a street engine. Building a high power race engine that has a short life expectancy though, there are many more things that are done in the pursuit of more power. I will however be continuing research tomorrow morning when I will be able to get a hold of more people and continue doing more research to confirm all the prior research I have already done.