Rod bearings have you seen this?

[motorhead]

That sure looks like this signs of oil stavation while under high load. Most of the wear is on the bottom half of the bearing ,atleast in the picture posted. Under high loading or high RPM the rod will stretch some and go out of round on the exhaust stroke due to inertia. Depending on your bearing clearance, which Im not sure what the factory uses in the LS3, you better have the right oil and enough pressure to keep the oil from being squeezed out during these times. That's what it looks like you have a case of. I highly doubt that is the result of any lean conditions. That doesn't take out rod bearings. That melts pistons. Detonation breaks pistions and bends rods. That looks like high loading with lack of proper lubrication.

You can't compare what a NASCAR engine uses for oil either to a stock bottom end. They are totally different animals. The NASCAR bottom end with have less bearing clearance built in for one. Which takes a ton of high dollar parts and special machining to allow for the use of highly engineered purpose built low viscosity racing oils.

[stevieturbo]

Originally Posted by 1KillerSS

Ill ask this one last time. wouldn't I see some sort of evidence with a lean condition. You can measure EGT's all day long, and read plugs. However I have done the next best, and the most extreme way of checking my tune, that is pulling my engine apart and looking at the pistons, and cylinder heads themselves, and they look perfect. If what you say was true then those cylinders would most certainly show it. I would tend to believe what Stevie and nick said, that I have a rod that is not quite straight somewhere.

Makes sense to me, I put the car into boost while it was down a cylinder and bent something. Next time im at t's garage ill look closer at the connecting rods. And to my knowledge ls3's have had plenty of failed oil pumps at least from what I have seen on C5. There were no codes to speak of.

Unless you shut the engine off right at the moment of any "lean condition"....then not really.

The only time there will be a record of problems long after the event...is if a piston is damaged/melted etc or there are obvious signs of detonation on the piston etc.

Definitely worth checking all rods for true though but if one was bent I'd have thought there would be signs on the bearing surfaces and/or perhaps the sides of the rods/crank where they run.

Of course sometimes the strangest smallest of issues can make the weirdest noises you might never associate with such a problem.

[1KillerSS]

Originally Posted by stevieturbo

Unless you shut the engine off right at the moment of any "lean condition"....then not really.

The only time there will be a record of problems long after the event...is if a piston is damaged/melted etc or there are obvious signs of detonation on the piston etc.

Definitely worth checking all rods for true though but if one was bent I'd have thought there would be signs on the bearing surfaces and/or perhaps the sides of the rods/crank where they run.

Of course sometimes the strangest smallest of issues can make the weirdest noises you might never associate with such a problem.

Thanks Stevie, for the input. Soon as I get back to t's garage, ill have a better look at the rods.


Once again, thanks a lot to all the members that have given my their input. I greatly appreciate it.

[UNRIVALED SS]

Good points posted. However, (1) rods bent- Detonation. (2) oil starvation, on top half of bearing, excessive pressure- Detonation. All ideas point the same direction. Pistons show signs of detonation when they break. They didn`t break but they transferred some extreme pressure.

Was this a methanol sprayed combination with a top mount roots/twin screw compressor? HMMMMMMMMMM. I know nitrous doesn`t distribute evenly through those, I doubt methanol would be any different.

Remember one thing on this. If you keep doing what you been doing, you`ll keep getting what you been getting.

I run a TVS2300 and I don`t run methanol because I can`t control it per cylinder. The way we use to have to tune each separate weber carburetor on street rods back in the day. They look good but take a lot of patience and time. Back two cylinders didn`t get the cool stuff and you had some issues. My final answer.

Good luck with it. I like to see these LS motors stay alive, so I can run it in the face of the blue oval guys.

[stevieturbo]

Pistons and the chamber can and do show signs of detonation long before any rod/bearing damage would occur.

But we havent seen those pieces yet

[1KillerSS]

I can get pictures of the pistons the next time I go to T's garage.

[wakespeak]

20w-50 is likely too thick unless you got it above 225F. The stock pump goes to bypass at just 50 psi, so you might be dumping a lot of volume back in the pan at revs unless the oil is hot. You need flow, not just pressure. I would use a 5w-40 like Mobii 1 Turbo Diesel Truck (also gas engine rated SN).

See this thread. He started with 15w-50 and got better results with 5w-40. Also FI.

[fif_gen_powa]

Originally Posted by wakespeak

20w-50 is likely too thick unless you got it above 225F. The stock pump goes to bypass at just 50 psi, so you might be dumping a lot of volume back in the pan at revs unless the oil is hot. You need flow, not just pressure. I would use a 5w-40 like Mobii 1 Turbo Diesel Truck (also gas engine rated SN).

See this thread. He started with 15w-50 and got better results with 5w-40. Also FI.

Looking into that m1 turbo diesel 5w40 it seems like a great oil for the turbo guys, thanks for the info