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SM newbie motor saga and recent failure w/ questions

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  • Location:Oakland
  • Region:CA
  • Car Year:1990
  • Car Number:22

So I lost a main bearing in my 1.6, and decided to do a 1.8 swap in my track car a few years ago.

Shortly thereafter, I decide to go all in and build my track car into a full spec miata.


Well, I quickly learned my 1.8 swap wasnt legal and I needed to go back to 1.6 ugh.

Got a freshly rebuilt long block from a racer on craigslist, that turned out have mismatch cam caps from other heads and cams wouldnt spin with more than finger tight bolts. Joy. 


After having to return another motor bought online, I scored a fresh rebuilt motor from a local wreck yard here in the bay area.

Took it to TFB for dyno tune, and got some decent #s for a junkyard dog, 115+hp/108+tq. I was excited and in the game after over 1year building and swaping motors!


I made the last race of the season this year in Oct 10,which was my 1st race. I stayed out of trouble, got to mix it up in the back and finished Sunday in 26th. So I dipped my toe in and got one step closer to getting my license. The motor ran good and car worked really well. Lap times were nothing special, mid to low 159s when clean laps, but I changed everything in the car and hadn't driven in over a year, so I was pleased, enough;) 


Had a great day at Sonoma on Friday Nov 27th, clicking solid low 158's with a personal best of 158.09, over a second faster than pervious best. So I was really excited about the season starter coming in March for Nasa Norcal region and getting a full season in and being in the mix and doing this.


That next Monday I went to Thunder hill to get some more seat time and try and learn the SM east route to see if I could settle into a competitive mid pack time. First run was a mostly feeling it out, but felt good that by end of day I could be where I wanted to be. Someone dumped oil all over the track in the group before my 2nd session. The entire track go kitty littered to soak it up, but I was linked up with some other SMs and it was almost like we welcomed the days of thunder lack of vision and the lost traction to further test our skills and feel.. Well, they had NBs with stock air boxes, and paper filters, and I had the highest flowing green cone.. The kitty litter was everywhere when I got back to the pit. I wondered about it getting into the motor while out there, but got sucked into stayin with the NBs and let it go. 


That next session would prove that was a bad decision after my motor blew a hole in the low end under the #4 piston underneath the header. I was able to pull off the track to a safe spot, thankfully, as the motor caught fire and I had to jump out, grab the extinguisher and get to putting it out before I lost more than a motor. Got the tow of shame back to the trailer and had a good 3h drive to think about what went wrong and where the budget would come from to make it right again. 


I yanked the head off, all was well, but the #4 piston valves were white. 

There was some damage to the piston top of piston 1, but that might have been the last failure prior to rebuild.

The motor was tuned lean, like most 1.6 getting #s up high. 

The #4 piston is not connected to the crank, but has the rod connected, so big end failure I guess.




Am I nuts to vilify the kitty litter used to absorb the oil and blame it for my engine failure?

Is it possible to lose a ring and then a rod bearing or rod as a result?

Or did I have a time bomb low end that was bound to blow sooner or later with a bad big end rod bearing?




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