Rod bearings have you seen this?

[1KillerSS]

Originally Posted by UNRIVALED SS

Details please.

Which 2 cylinders? (#)
Power adder?
Oil weight?

My first opinion is detonation causing severe pressure on the bearing rod side as it makes the power stroke. Could be caused by a lot of things. Example , intake leak , but only under high boost. AFR looks good tuning because the other 6 are good. Need more info. If the 2 cylinders are on the same side and joining then it's a indicator versus opposite sides on the same journal or separated all together. I'm very interested in as much detail as you can offer.

Back two cylinders 7 and 8
Twin 54/57's with dual nozzle meth
10 40 Valvoline VR1 Full Synthetic Racing Oil

I can look at all my data logs, and see that I was not loosing boost, and all my afr data was perfect. Thats backed up by what we saw in the combustion chambers, they all looked surprisingly good. It did look like there was a valve seal that looked to have just started leaking in one cylinder, but that was cylinder 3 if I remember correctly. and it was not very obvious. ttshovel can elaborate better for me on that. He and I were the ones working on the tear down. He frankly knows a hell of a lot more than me about it.

[ttshovel]

There was quite a bit of oil in cylinder 5, most likely a valve seal. It could have definetly been a contributing factor.

I do believe it was the back two cylinders as well

[1KillerSS]

Correction, I was running 20 50 VR1

[pancherj]

If oil got into the chamber, it could definitely cause detonation. I lost a piston on my L98 Iroc like this. Ran great for a few hundred passes and then BOOM. Oil in the intake runner going to # 7 and the rest were dry.

[1KillerSS]

Originally Posted by pancherj

If oil got into the chamber, it could definitely cause detonation. I lost a piston on my L98 Iroc like this. Ran great for a few hundred passes and then BOOM. Oil in the intake runner going to # 7 and the rest were dry.

Oil was found in cylinder number 5, not 7 and 8. There was no boom. Just some light ticking.

[fif_gen_powa]

Originally Posted by 1KillerSS

Correction, I was running 20 50 VR1

On a stock ls3? Was this oil weight recommended to be run just because you're turbocharged?

[1KillerSS]

Originally Posted by fif_gen_powa

On a stock ls3? Was this oil weight recommended to be run just because you're turbocharged?

Yes, are you thinking that this is because of the weight of oil I was running?

[UNRIVALED SS]

I have a few ideas. Really hoping someone can jump in and confirm.
First anytime oil is introduced into fuel air mix it effectively lowers octane even in small amounts.
Second we use to run a Pontiac 455 with a pro charger blowing through a carb. It would blow the head gasket between the 7-8 from time to time. I found that this was caused by differences in intake runner length and the back cylinder was leaning out. Trial and error deduction.
Third running heavier oil with clearances build tight for 100K reliability is generally a no no. Even with the heat associates with a turbo combination. It'll work, till it doesn't. The thing with protection bearings from pressure related failure is 1. Oil volume 2. Clearance for it to flow through. Remeber when dealing with hydrolics , pressure is inversely related to volume. So when we see added oil pressure with heavier oil the perception is we are better protected but the volume is actually reduced . The way we use to run 8 or 9 pounds of fuel pressure on nitrous hot rods on the street because fuel was running through big lines to a carb.

Anyway , sorry about the rambling . Sorry to see you're having problems. I know how it feels. I've had zero oil pressure a few times. Bad feeling. I would go back with a quality ported oil pump and undersized bearings to add a bit of clearance. Then that 20-50 can work better for you. I think the ZR1 oil is pretty good stuff.

Good luck with it.

[fif_gen_powa]

Originally Posted by 1KillerSS

Yes, are you thinking that this is because of the weight of oil I was running?

I'm in no way qualified to make that assumption but I do always hear to run a weight based on tolerances of the engine which would be a much lighter oem recommended 5w30 regardless of other factors

[1KillerSS]

The whole story of how this happened goes like this.




The car started to miss a little, instead of parking it and pulling the plugs at the least, I continued to drive it. One day I got aggressive with the car and put the car I to boost. The miss was intermittent and I blew it off. When I punched the car it was most likely still down a cylinder. The miss felt like it was a loaded plug or something so when I made the decision to put the car Into boost, all I did was brake something.

Like I said earlier a few people have said this could be due to oil starvation. So far that makes the most sense. Heavier oil. I usually run 10 40 but they were out and was told I could also run 20 50


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[94guy]

20/50 oil?

[1KillerSS]

Originally Posted by 94guy

20/50 oil?

Yes, I have read, and been told, that it was ok to use that oil. They have been reputable people and are on this forum. I won't say who. However I have read conflicting information regarding this subject. I usually run 10 40, but like I said they were out, 20 50 is not my first choice, however being under the impression that it was ok to use, I went ahead and used it. IF this damage is due to using 50w oil, then shame on me.

[Unreal]

Not saying 20-50 is "bad" but it just depends. I wouldn't consider that oil in a colder climate, but if you were letting the oil warm up fully, and it was a warm place, I doubt that was an issue. Now if you were beating on it cold, it could have contributed.

[stevieturbo]

So it's all apart...what do the pistons look like ?

All good, no cracked ringlands or anything like that ?