And if what you believe is true, every engine that fails would suffer identical damage on all 8 cylinders.....which everyone knows is never the case

Improper tuning caused the damage whilst boosted. Fact.

 

I agree, I have seen this happen many times. Bob

 

Injectors usually vary 3-4% (or worse) and air distribution to the cylinders isn't even either, esp with factory intakes.

It's nice to have an ECU that can adjust individual cylinder fuel trims, I always add fuel to my hottest cylinders. 6 and 7 are usually the worst. I add 7% to #6, but I'm pulling or adding fuel on 5 cyls to get my plugs to all look uniform. Pretty easy to see which cylinder is the hot one if you start low on timing and read the plug. If not, you have to tune all the cylinders off your hottest.

Zbrown did this little leaf blower test with a factory manifold. Pretty amazing how much difference there is cyl to cyl on a factory intake VS the one he made.

Stock LS3 intake

VS Intake he made...

 

Not long ago I read a thread where someone added 10% fuel and reduced timing by 2* under boost on cylinder 7 to get the plug to look like the others. Seems more of an "over air" situation rather than an "under fueled" issue. Individual cylinder tuning can be your friend. People do the same thing on fogger nitrous systems as well to keep all the cylinders happy.

 

Think about what you are saying in reverse. Imagine he tuned that one single cylinder to be richer or use less timing. The condition present would have been identical as before, minus the intense pressure spikes that lead to locked rings. With hindsight, we can see that all cylinder may have been present, but their conditions were different because individual cylinder tuning was not employed.

In that case, 7/8 or 87.5% of the engine was tuned properly, and the remaining percentage was not tuned properly. The problem, was therefore not with the tune itself (since 87% of the engine was tuned right) but instead there were contributing factors that affected the one single cylinder.

I am not saying you are wrong; Surely, 12.5% of that engine's damage was "tune related" but not in the traditional sense where the whole map needs to be fixed, but rather, that there is a defining feature of that particular engine (mechanical/design/electronic) which caused the failure.

In other words, setting the whole tune richer or to use less timing or boost would fix that one cylinder at the expense of all the others. This would be "re-tuning the fuel map or spark map" and is not the correct way (tuning) to fix the issue. Instead, we need to directly address whatever factors are affecting that single cylinder. (you still may call this tuning, for example plug indexing is a form of tuning) the terminology is bland here since anything we do or touch is called 'tuning' it was only my desire to point out that 'tuning' in the traditional sense of modifying fuel/spark tables is/was not the answer in this case for a competent solution, unless it were individually directed at that cylinder to solve an issue with VE where it happened to be getting fuller for some reason, and that still leaves the engine 87%, or the majority of it "tuned" and us wondering if that one cylinder really is more full than the others, or if it were something else.

 

15* WITH 15 PSI of boost and no IC is what killed that motor. A 5.3 can survive several low boost passes at 12.0 AFR on 93 octane as long as the timing is correct and air temperature is under control.
Always start low on timing and rich AFR, otherwise you can kill a engine in only 1 pass.
You don't have to melt/break all 8 pistons to blame the tune. I have seen a lot with only #7 dead to know it.

 

Well you can bet that if the engine had been tuned correctly...ie spark/fuel tables and how they apply to the engine in question....then it would not have blown up. Simple as.

It isnt a single cylinder engine, he doesnt have the means or wasnt monitoring it on a single cylinder basis so it's largely irrelevant to comment on that basis. It's common knowledge on any engine platform you tune for the entire engine to be safe if you dont have the ability or means to take each cylinder individually...and even if you did, when something fails, one will always fail first, all 8 never fail exactly the same at exactly the same time..

Doesnt matter whether it's tuning related, mechanical etc etc. When you see an engine break a conrod, all 8 dont break at once, when you see it blow a head gasket, all 8 dont blow at once...etc etc

 

Well now wait a minute. Even with a proper air fuel ratio and spark advance, there is still a limit imposed by the OEM ring gap and piston material. We can not assume that because fuel or spark is involved with generating an effective cylinder pressure that we are not exceeding the operating limits of the OEM parts involved.

That said, if you knew in advance one cylinder was "weak" then steps should be taken from experience to improve the outcome. Thats more of a research problem than an engine problem. I agree that it is the weakest link that fails- pure logic there. The next logical step in the chain of command is to implement improvements that generate better outcomes- if it happens to be a single cylinder, then it only accounts for 12.5% of the engine (the weakest link is only 12.5% of your piston area for example) so adjusting 87% of the engine's fuel/timing would be a band-aid whereas improving your weakest link would be an improvement and non-subtractive to the rest of your engine's performance. If the operator had, for example, added methanol injection or water injection to control temperature, it might lower engine output while it would also improve headroom for boost- but it would NOT remove the limit imposed by the ring end gap or piston materials. In other words, "tuning" by intercooling/fueling/timing/water/indexing/port modifications/etc can all improve the outcome of combustion, but none of those items can change the outcome of the weakest link in the OEM bottom end (the ring/piston in this case) so saying "it needed better tuning" is like saying "it would have lived longer with better tuning but the end result is still the same due to limitations imposed by materials".

I have seen an engine bend all 6 rods (inline 6) at high torque low rpm situation. I have seen single cylinders fail also- but usually there is some evidence that the others are affected in some way. Detonation by running out of injector is a great example where each cylinder will display its own pitting/deterioration and one finally gives up, or the HG finally goes. So it goes both ways. I found it strange that in THIS thread, THIS engine here had a VERY nasty looking piston, deteriorated to $#!T, and all the others look fine. Thats why I suggested single injector or oil aspiration related failure. I did NOT know about any "design flaw" in which the cylinder #7 of every engine of this type (research related issue) was so commonly found wrecked, but I am happy to know now, and I will keep it in mind in the future and include it with my research.