But they are kind of warming you up to the idea that its not their fault, because there really isn't anything mechanically that would cause detonation. That said, I'm not as convinced detonation caused this in an NA engine and for reasons you mentioned. Examining your tuning/ignition timing curve in your Hondata should tell everyone what they need to know. Also If it was the tune, it wouldn't just be two cylinders, it would be all of them. Warn coil packs isn't going to cause detonation. So I don't know, still not clear to me what the smoking gun is here either. The spark plugs should be wasted and tops of pistons pitted if there was enough detonation to blow out the ring lands id think. But these things looked to have no signs whatso ever. It seems more likely either someone messed up on the ring gap or instillation, wrong rings or something like that. . I could be totally wrong, but that's my thinking on all this based on what i'm seeing and what I know about engines in general and I think are totally fair assessments. I would be asking/pressing these questions to inline to see what they say and come up with at some point if it looks like they are not going to take responsibility. You want to be armed with as much knowledge as possible here if they try and take advantage of any ignorance on your part.

 

Question for the thread as I’m getting conflicting opinions.

If I had a perfectly running tune on my original motor (again, OEM) and then did this rebuild back to OEM spec, “0 miles”, should I have done a complete retune?

I’m getting some opinions that timing could have changed between the original motor and this rebuilt one - as in a timing sync between the ECU and the physical timing...

opinions?

 

What did you say this lasted, 150 miles? During those miles, how did you drive the car? If RPMs were kept low and you weren't beating on it, there's no way detonation would have caused that catastrophe.

 

OP sounds like a sensible, logical person. There's no way I can see him/her going ham on a new motor...

 

Agree that if it were severe detonation, there would be evidence on plugs, on tops of pistons.

I want to mention one thing, detonation could be caused by something mechanical. If the piston tops had issues, where hot spots could form, this could pre-ignite mixture. For example, something like this can happen if you try to clean pistons with something like a wire brush on a drill. It causes pitting which can cause detonation. Obviously these are new pistons and this didn't happen here. Just example of how mechanical issue can cause detonation. Basically, if it were proven to be detonation, it doesn't automatically mean it couldn't somehow be the build.

Can't see how it can be the coils. Misfire does not cause extreme detonation.

If the build altered the ideal tune, then my question would be why those two cylinders needed a new tune so badly they grenaded themselves in 150 break in miles, and the other two cylinders survived their mistune completely unscathed?

Still seems to point to something different in the build of those two cylinders than the others.

 

I don't disagree with your assessment in total, and I don't want to get too far into the weeds here, but I immediately excluded mechanical culprit for detonation because its just not an issue on a new spec engine. A used old nasty engine with issues, yes I agree with you pre ignition can happen. I still question if typically severe enough to cause total ring land failure though. Typically you would just see a very slow decline with evidence on plugs long before this kind of damage would ever happen.I mean even the factory pistons have stamped lettering on them, so even pronounced irregularity on piston surface clearly isn't enough to create hot spots and pre ignition to occur. It has to be far more sharp and extreme/issue, and I just don't see a soundly constructed engine destroy itself through self imposed detonation. It has to be something mechanical if its not the tune, and if the tune is good then what does that leave?

 

OP, I would give inline pro every opportunity to investigate this and do the right thing what ever that is, check out your tune file etc, whatever they feel they need to do to get to the bottom of this. No doubt they are having this very similar debate among themselves as we are now doing in this thread. If you sense your getting to a dead end with no favorable resolve, I wouldn't hesitant to even show them this thread and debate points being brought forth here. They may even decide to chime in themselves at some point if they feel that's advantageous. Knowing that they have a audience and a pretty knowledgeable one isn't a bad thing either.

 

I am the one suggesting that even with a new ECU, never mind a new motor or a rebuilt motor you should always do your due diligence and check ignition sync including at higher RPMs to set any offset and runaway @ higher RPMs. Also make sure that TDC marking is actually TDC.

It's hard to blame the tune especially since it worked well on stock motor pre-rebuild, so the only thing that stands out to me (from tune aspect) that could've caused drastic timing deviation is sync, even though supposedly that's highly unlikely.

Yes we're all guessing here but from what I've learnt is that bad ring gap will break ring lands like we see in our photos and is/can be mistaken for detonation.

 

Also, is anyone else not seeing any melting on the piston? If it was detonation we'd see it I think especially in extreme case.

To me it looks like mechanical, so pistons were binding up, broken ring lands, scored walls.

 

Looks like the rings were too tight. The ring gap corresponds to where the damage has occurred on the piston and would explain the markings all around the bore