As the FD was feeling rather sluggish recently in an autox, I checked the compression and found 2 faces on the front rotor at 74psi, significantly lower than the other face, which was in the high 80s.

So the engine has been torn down, and the damage can be seen in the photos. A dented rotor and a broken apex seal (the broken piece was still in place)

It does appear something was sucked into the intake, and I can recall something happening at an event a few months ago, partway through an autox run.

The car stumbled a bit then didn't feel quite the same - a disturbance in the force.

When I saw the damage I was a bit puzzled (still am) as I am always quite careful when taking anything apart. There are covers for the intake should the UIM be removed.

Here's what is really puzzling; there is no damage at all to the turbo.

See inspection videos here: Turbo Inspection

The light areas on the turbine are simply spots that were touched and some carbon was wiped off.






Next I took the muffler apart to see if anything was caught there. This is either a small rock or a chunk of carbon. No metallic objects were found.




Any speculation on how this is possible?

 

Sorry man... that really sucks! I would try to slice/break that thing in half to see what it is made of. That could give you a clue about it's origin and possibility of going thru the engine.

 

I crushed that bit with a hammer. When rubbing the the bits between my fingers it did turn them a bit black.

Not sure if it was hard enough to cause that rotor damage.

 

That's odd! It is definitely a foreign object damage, that's not where apex seals break due to detonation.

I think you just succumbed to a freak accident. I wouldn't get too carried away trying to find the source. I doubt there's anything you did to cause it or anything you could have done to prevent it.

How did the rotor housing fare?

Dale

 

not a scratch on them, they look nearly new

 

You got away pretty well then! New rotor, new apex seals, freshen things up and back in business. Glad it didn't take out the turbo!

Dale

 

Water injection all the time is a saver.

 

Are your plugs OK? I've heard of electrodes breaking off and causing such havoc. What's your overall setup like?

 

Water injection has been installed for quite some time. However on that day the pump got clogged and it wasn't working.

The dent in the rotor would be hard to explain by detonation alone.

 

T04S, 15 lbs boost. Not running lean by any means.

Adaptronic Select, same tune that was running for quite some time. Weather that day was warmish.

The motor and cooling system in this car keep it from ever getting hot, even on very hot days.

The plugs were fine physically, just dirty.

 

I had an EGT probe do that once at autox.
Broke off in one exhaust manifold runner (divided manifold), traveled through the single wastegate into the other exhaust runner and pinched the apex seal in the slot with a dent in the rotor.

Check your exhaust gaskets (especially the thin section between the runners on a divided turbo flange). That looks like a ball of burnt up exhaust gasket.

 

The EGT probes are intact, as are all the gaskets.

However I took a closer look at the turbo manifold. Not only is the divider cracked, there appears to be a chunk missing.