rod bearing spun...

[UCF201101]

I finally installed my megasquirt ecu. I also had the car tuned at 10psi. When the shop was tuning it, they had made 18 passes to tweek the car until it ran great. I drove the car home which is about an hour away. I only stomped on it in third and forth gear. WHen I got home, I took my sister for a drive. When we got back, I told her to keep the car running and pop the hood open. As I was listening to the motor, an unexpectedly faith knock was present. My first intial response was a lifter. To be sure, I pulled the oil pan off and found out that all four cap bolts were tight but the caps were a tiny loose. I pulled off cylinder 1 rod bearing and it had spun. While building the engine, I made sure that I torqued it right. I was using eagle rod with arp bolts. I made two passes over them in order and my dad made another pass with a different torque wrench (band new). I had my crank turuned .010 and brand new clevite rod bearings. I also had a high volume oil pump. THe oil pressure gauge was fine and did not show up as sucking the pan dry. Any ideas to why my car failed? Should I go with a hv melling oil pump again for the otc oil pump at advance? I have spent way to much money and am in the process of rebuilding. I have all the parts I need but need some much needed info. Thank you for your suggestions.

 

[BogusSVO]

Stock pump is all you need for a car that is mainly street driven.

HP/HV pumps will pass the oil too fast and not draw the heat out of the bearing faces or crank surface.

How well did you clean the crank oil gallies?

Pics of the bearings?

 

[My1GLaser]

Did you mic the crank journal to make sure it was cut correctly, and the rod end so you would know what your oil clearances were? Did you at least plastigauge? Did only one spin?

 

[bullettdsm]

I use OEM oil pump on my builds. I don't like Mellings for various different reasons (one of which is failure rate that I have seen).

Cut crank? If I had to suspect something, it would be the crank. Any pics? and how did the other rods bearings look? (pics of others as well)

 

[glowryder]

dam, same story with me, except less miles .. Mine turned out to be the machine shop didnt really care about my application and have it to tight of tollerances. I was also runnign clevites. Did the shop tell you your Tollerances and what Oil weight to use? if not. then that would be where my money is..

 

[Hydecotsi]

I would go with the oem also much less faluiar rate. Also its hard to say what could have caused it ther are 100000 resons why it could happen have any crank walk issuses? Their know for that. And like everyone said pic s would help a lot man

 

[glowryder]

Mopar doesnt make / discontinued any bearing other then standard for us.

 

[UCF201101]

Thanks guys for your post. I currently do not have the bearings. They are at the machine shop. I have been going to this machine shop for years. I do trust him;however, I was confident with my build. I used 5w-30. Only one rod bearing spun. THe other bearings had some wear and tear but not as bad as the other one. I had looked up on Clevites bearing website and it had showed a picture just like the bearing that had spun. It said that it was, "Catastrophic engine failure." I will take pictures within the next two days when I get the crank. I did not use plasigauge; however, I did buy a set for my next build. How can I prevent crank walk? I will try and take a snap shot of my megasquirt timing to let everyone look at it. I just want to try and delete some of these confounding variables.

 

[glowryder]

We dont get Crank walk like the GST/X guys. not in that sense anyway. Id be more interested to see if you were detonating.

 

[UCF201101]

How can I tell? My afr was 11 to 12. I can take a snap shot of the fuel maps too?

 

[glowryder]

12 is to lean imo.. your using MS? , when i got mine tuned, it was tuned well enuff to not flux between 11.5 and 11.6. you have to account for tollerance stack.. like inaccurate guage readings, etc..

were you logging? upload the log of your WOT pulls. and look at the bearings, see if they kinda "flattend out"

 

[UCF201101]

I was not logging when I first got the car back. However, they were logging on dyno. I can't get a hold of the guy. The bearing is smashed. I will take pictures today since I am getting my crank and rods back. Something doesn't seem right. I had only 6000 miles on the motor before I had it tuned. Ofcourse the bearings had some wear on them. But cylinder 1 had the worst bearing.

 

[YZFR1]

More times than not you are not going to detonate because of running lean (not making enough pressure to do so) and 12's are not even that lean to begin with. My money would be on the cut crank or contamination because of a cut crank.

 

[glowryder]

for a street tune.. i think 12 is on the lean side. but i guess to each their own, i prefer 11.8, but i give it some room as for us whom run standalone, its dictated by an AFR guage, which could be off .1 or .2, thus the tolerance.. Ive detonated on 8psi, my spark may was crap and i was just learing MS and going for it, go big or go home, i did both . Depends on how bad the det is and the timing your using as well, but its not hugely common on such low boost, but its possible.. The bearing will tell us if its det or contaimation. Another cause could be poor machining, i ran itno that with my last build.. Its hard to point at anything without analizing the bearings. i dont think its oil control as #4 would have toasted first. but. we shall see get those pix up.

 

[UCF201101]

Attached is megasquirt tune