Six_Shooter's money pit and time vampire... v.240Z

[Purple pit]

Oh man that is nasty.

[34blazer]

Nice work! Any data on this failure? Boost spike, knock?

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[Guest]

More carnage:

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[Guest]

Last bit of the carnage:

Failure20.jpg

#3 on the right and what's left of #4 of the left...
Failure21.jpg

[Guest]

I have to pull the data log from my AEM Failsafe gauge to see if there was any sort of spike, but I don't recall there being any at the time.
I think I've just abused the stock parts for long enough that they decided to give up.

I believe that #4 let go first, not sure whether it was the skirt or the ring land first, but then there wasn't enough space for piston and rod and extra length under the head so the rod then broke, and that breakage caused lots of debris and took out the #3 rod...

[34blazer]

What kind of power do you think it was producing?

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[Guest]

Speculating, because I never did get to the track with this combo to get any solid numbers, but I'd say high 300s, if not low 400s. There was a lot more get up and go with the new cam over the old one and I know that was low 300s at that point.

[34blazer]

Nice. Were the rings filed at all or did you leave those alone?

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[Guest]

The ring gaps were opened when I had it apart in the summer.

[34blazer]

Oh ok. I'm worried about the strength of the rods, even though they are PM, they seem kinda puny to me. Where did you shift at?

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[Guest]

Usually hit 6300 to 6400 RPM. A little lower in first, I think I had the shift light set to 6000 RPM for first gear. I have taken it close to 7000 RPM a few times.

I only think the rods failed because the piston failed first from what it looks like to me. #3 was definitely collateral damage.

I've already talked to my engine builder friend, about the road to rebuild, and I'm going to build this for my end goals, with aftermarket rods and custom pistons.

[34blazer]

I'm interested in what you come up with for pistons/connecting rods

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[Superdave]

Nice Carnage!

[34blazer]

I ventured back to the beginning of the thread, right around the time where it cooked a head gasket. Looks like the same cylinder? May have slightly uneven airflow distribution with that upper intake. Have any old spark plugs, or the current ones to peek at? Im curious to see where the AFR's were at just before it went kablooey.

[Xnke]

Not enough ring gap, looks like. Detonation severe enough to break off that much of the ring land would show up in you cylinder head combustion chambers, or on the undamaged area of the piston as little pockmarks. What did you open the rings up to?

Keep in mind hypereutectic pistons require a much larger (20 to 30 percent, in many cases) top ring gap compared to a non-hypereutectic piston. The top rings on my 3.4L are gapped at 0.028", compared to 0.018" that would normally be fitted to that engine. All because I'm running 3400 hypereutectic pistons.