moodah Posted April 24, 2013 Share Posted April 24, 2013 Hi Guys, Does anyone have any idea what the possible cause of this is? Quote Link to comment Share on other sites More sharing options...
RB26powered74zcar Posted April 24, 2013 Share Posted April 24, 2013 Major detonation.... Quote Link to comment Share on other sites More sharing options...
moodah Posted April 24, 2013 Author Share Posted April 24, 2013 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? Quote Link to comment Share on other sites More sharing options...
stony Posted April 24, 2013 Share Posted April 24, 2013 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. Quote Link to comment Share on other sites More sharing options...
moodah Posted April 24, 2013 Author Share Posted April 24, 2013 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. Quote Link to comment Share on other sites More sharing options...
Lazeum Posted April 24, 2013 Share Posted April 24, 2013 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. Quote Link to comment Share on other sites More sharing options...
pat1 Posted April 24, 2013 Share Posted April 24, 2013 That's not detonation, something was in that cylinder and banged it up. That thing has been hammered! Quote Link to comment Share on other sites More sharing options...
johnc Posted April 24, 2013 Share Posted April 24, 2013 FOD - Foreign Object Damage. Quote Link to comment Share on other sites More sharing options...
KAZU Posted April 24, 2013 Share Posted April 24, 2013 My guess is the intake valve guides have been broken. Quote Link to comment Share on other sites More sharing options...
RB26powered74zcar Posted April 24, 2013 Share Posted April 24, 2013 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. Quote Link to comment Share on other sites More sharing options...
ZT-R Posted April 25, 2013 Share Posted April 25, 2013 Being on only the quench pad yes i say that is detonation. Especially being on 1 and 6. Quote Link to comment Share on other sites More sharing options...
900ss Posted April 25, 2013 Share Posted April 25, 2013 FOD - Foreign Object Damage. +1 imo Something's got in there ... like your turbo blades you mention ! Quote Link to comment Share on other sites More sharing options...
Wedge Posted April 26, 2013 Share Posted April 26, 2013 (edited) 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 April 26, 2013 by Wedge Quote Link to comment Share on other sites More sharing options...
NewZed Posted April 26, 2013 Share Posted April 26, 2013 This thread is following the same path as the last one like this - http://forums.hybridz.org/topic/98290-rb26-head-removed-and-found-this/ Quote Link to comment Share on other sites More sharing options...
RB26powered74zcar Posted April 26, 2013 Share Posted April 26, 2013 This thread is following the same path as the last one like this - http://forums.hybridz.org/topic/98290-rb26-head-removed-and-found-this/ LOL.... yep. Quote Link to comment Share on other sites More sharing options...
cheftrd Posted April 29, 2013 Share Posted April 29, 2013 Detonation causes the plug electrode ceramic insulation to fracture and fall into the cylinder. Then it beats the pads to death. All too common. Quote Link to comment Share on other sites More sharing options...
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