speeder Posted April 12, 2003 Share Posted April 12, 2003 Thought I'd share some pictures of some pistons I've known. My first ruined pistons from too much boost on my BAE turbo kitted '77. My education began like this about 20 years ago. 77 Piston A piston out of my brother's GN (This problem runs in the family) Buick Piston One of my forged pistons after running with 6* more advance than I thought I had (Electromotive crank angle sensor inadvertantly advanced by 1 tooth) This was last February. Note the piece of the 2nd ring jammed in the groove. Venolia Piston All 6 of these pistons from a stock ZXT motor customized because the head I put on that motor had been milled about .100 more than I realized. Motor had more than 1.5 points of compression more than I expected. This happened at SEZS II on the second pass. Ole Blue got me back to Florida! ZXT Pistons Finally, out of the above set, This is #6 piston with damage from a blown Steel gasket! ZXT Piston Like I said in my other post, damage like this is kinda fascinating after you get over being horrified. The moral(s) of this story? THINK! Recheck everything. Don't get in a hurry. These are all really basic errors - Every time (except for my brother - he's an idiot) I knew better. Yeah, I'm a Stooge. Quote Link to comment Share on other sites More sharing options...
240Z Turbo Posted April 12, 2003 Share Posted April 12, 2003 Rick, you should always check your actual timing with a timing light. While the motor is out, dial in TDC and make the marks so when it is running you can easily verify them with a timing light. WHOOPS! Quote Link to comment Share on other sites More sharing options...
Guest norm[T12SDSUD] Posted April 12, 2003 Share Posted April 12, 2003 Yup same thing happened to me last year when I got that set of junkyard pistons that should of had a 10.9 cc dish but turned out to be 7.9cc. One hot afternoon at the track and 4 pistons let go at once. NEVER ASSUME!! later Quote Link to comment Share on other sites More sharing options...
speeder Posted April 12, 2003 Author Share Posted April 12, 2003 James, you're preaching to the choir Like Norm says, my problem is that I ASSumed. Quote Link to comment Share on other sites More sharing options...
jgkurz Posted April 12, 2003 Share Posted April 12, 2003 Good advice guys. I've always blindly trusted the Tec be accurate. Let's just say I'll be taking out the timing light real soon!. Later Quote Link to comment Share on other sites More sharing options...
slownrusty Posted April 13, 2003 Share Posted April 13, 2003 Rick - you're a better man than me bro! I would be shaking my head by the time the second set of pistons went south and probably taken up a new hobby...cake baking.....bowling? Either way - pretty incredible the damage, especially the one picture showing pieces of the skirts missing off all pistons. How much boost were you running at the time as well? Did you have an EGT in the car or did you audibly hear the detonatation when the TEC adavance your timing? Good luck in the future! Best regards - Yasin Quote Link to comment Share on other sites More sharing options...
speeder Posted April 13, 2003 Author Share Posted April 13, 2003 After every disaster I always come back stronger. In this case it's the excuse to begin that Stroker. The destructon of the forged pistons in the first L28 hurt - that was a really sweet motor. That one I simply screwed up on when I built the crank angle sensor. I simply counted teeth wrong on the trigger wheel while statically timing the setup. I was running 18PSI with no audible detonation and 11.5:1 AFR indicated on my wideband AFM. The failure came when I began to run more timing to try to improve spool up characteristics of the T61. Earlier, I had a failure in the FPR diaphragm that caused a lean condition, and that did produce brief audible detonation (I got out of it immediately). Maybe that was the start of the damage, but excessive timing finished it. This happened just as I was wrapping up preparations for the SEZSII. I did go to the Reynolds event the next week with a stock ZXT short block donated by Z-Gad - but I put an extra N42 head I had on this. That head was ported and had a good Isky turbo cam in it. Since my original head was an N42 , I "assumed " that the setup would be similar. Wrong! That one was excessively shaved. Again, no audible detonation and (with the timing accurate now) the car was brutal fast at 16PSI, but the cast pistons couldn't stand it. I will definitely have an EGT guage when I get running again. All of this is Tuning 101. Simple stuff, but I definitely have been humbled and re-educated by all of this. But give up? Nah. Quote Link to comment Share on other sites More sharing options...
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