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Uh oh.. Whats been happening in this head?


moodah

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Really? Are you sure?

 

These pictures are from cylinders 1 & 6.

 

Cylinders 2,3,4 & 5 look absolutely perfect.

 

It is an RB26 head. The engine was completely stock.

 

One of the turbos was seized and missing a few of its ceramic turbine blades. Obviously the boost was jacked up too high.

 

I don't get why this is only on cylinders 1 & 6 though?

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were the spark plugs in it when you took it apart or did you get it like this? My guess would be the damage came from detonation that broke the ends of the electrodes off and they bounced around in there for a while.

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Hmm. It had a full set of iridium Greddy plugs in great condition. 

 

Looks to me like there was debris bouncing round in the bores as well.. Couldnt possibly be two cylinders that had electrodes break off....

 

It does appear that some of the aluminium damage has caused parts to break off though.. id guess this is where the debris has come from..

 

I wasnt aware detonation could cause this to a head though? No real big deal i guess.. Ill just weld it up and file it back.

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How do the pistons look like? If it was a spark plug debris, the pistons should have some markings also at the same spot.

 

It makes sense to be detonation. It happened at quench area were the pressure is the greatest & the furthest from spark.

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The question was;

 

 

" Hi Guys,

 

Does anyone have any idea what the possible cause of this is? "

 

 

Detonation may not have actually done all that damage, but I guarantee you it was the cause of the damage. Below is the head I pulled off the first rb26 I bought, and it was trashed just like OP's. When I opened it up, most of the chambers looked like this and there was little BB looking bits of melted alum in the cyl bouncing around.

 

The cause was severe detonation that melted the piston crown / ringlands, which caused pieces of broken rings/ ringlands/ moultin alum to help do the damage.

 

post-181-0-11321900-1366817304_thumb.jpg

 

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FOD as mentioned nothing tells you that the spark plugs werent replaced and the Greddy put their after the damage and sold to you. Sorry for you hope you didnt pay to much for it.

Edited by Wedge
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