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R Boom Opionons? Pics Inside...

Shockster0429
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Shockster0429 Enthusiast

Shockster0429

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Well finally after a good deal of issues I was able to get my 35r rb25 back on the dyno this afternoon. Sorted out a glitching RPM issue.. "or so I thought" by cleaning out my CAS. Sure enough my car fired right up after this. This issue was a glitch that was being sent to the ECU by the CAS giving crazy RPM readings. For instance while cranking at 300 rpms, it might spike to 16000 rpm or 10000 rpm signal. Causing the piston to missfire at say bottom dead center making it impossible to start. Well I thought it was gone...

264809931.jpg

anyway. Back to tuning. Car had been running for about 2 hours now, no issues. Tuner was making pulls in 500 rpms increments. Left the timing alone and was doing a/f tuning all at 11.2 +- .1. All was fine. Boost was set to 14psi. Made a 6500 pass no problem and put down 300rwhp.. keep in mind no timing settings were changed yet. So a 7500 pass was up next. Pull sounded fine, loud as **** so our ears are all covered so we might have not heard something... tuner is watching a/f's so he wouldn't have noticed the graph... Car hit redline, idled for a few seconds then shut off and died... Throwing an RPM code.. which was stating the RPMS are fu*ked. So tries cranking cranking, RPMS are spiking like they had been before when the car wouldn't start... Now the graph.. Looks like a mountain not a curve, all is good until around 5000rpms...... after that it seems to be devesation...

264809945.jpg

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Heres what my plugs now looked like. They got so hot that the conductor and porcilin was melted off pretty much all the way. My thoughts are that the CAS started glitching out around 5000 rpm throwing say an RPM signal of 16000 rpm in worst case senerio... most likely caushing some form of predetenation... My tuner thought it was valve float initatialy when he looked at the graph, he had a simillar issue with an SR. But after inspection of all the lifters and plugs we realized that wasn't possible..

compress test goes in 1-6 order, 120 110 110 120 100 60 ... We leak down tested her doesn't seem to be the rings since theres no crank case pressure leaking though... We are concluding that the tip of the plug's are no melted at the bottom side of my valves preventing them from closing all the way... or it might have damaged them.

Anyone ever heard of a CAS doing this type of glitching? and any thoughts on the **** *** compression.. Motor will be removed in a few days for inspection of damage.. not cool for sure. Motor was looking to make about 400rwhp that pass at 14 psi w/o touching base timing.. she will be down for months now.

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TurboX Mentor

TurboX

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Posted

Strange you did not get any backfiring if the plug fragments are holding the valves open a bit?

Amazing damage even though they are crap plugs and is that an NGK in there?

What heat range were they when they were in one piece?

And do you have splitfire coilpacks that would have kept the spark going with that much gap!

Serious detonation happening at the torque peak I would say.

Hope its not to hard or expensive to repair!

Shockster0429 Enthusiast

Shockster0429

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Strange you did not get any backfiring if the plug fragments are holding the valves open a bit?

Amazing damage even though they are crap plugs and is that an NGK in there?

What heat range were they when they were in one piece?

And do you have splitfire coilpacks that would have kept the spark going with that much gap!

Serious detonation happening at the torque peak I would say.

Hope its not to hard or expensive to repair!

Yeah there wasnt any backfiring, it still sounded smooth like usual. Although nice plume of black smoke came out during that time... obviously unburnt fuel from the plugs being done... And at the end of the pull a nice blue cloud as well. No load bangs no explosions, no steam or smoke from the bay, anything like that..

NGK wasn't my plug, we had one plug that survived and place it back in the motor to see if she would even start with 5 fresh new plugs. Plugs are coppers gapped at .8mm, coils are bosch microtech ones. Being fed by an x6 box and lt12s computer.

tacker Mentor

tacker

Posted
Posted

mate i have seen spark plugs that will either earth to the side of the thread or to the top of the piston when it reaches TDC doesnt do the top of the piston any good at all.

Hope the damage is not to bad!

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