What would cause.....?

[bornagain]

Okay so whether or not you are familiar with my last build or not this is more of a discussion and i dont need flaming, with that said, tonight i finished tearing down the block of my m30b32 turbo powered e30. Back story goes as such, after the rebuild(10,000km ago) i had a lot of blow by and getting worse and worse, to the point where the oil would fill my catch can and then pressurize that and then spray it out of the breather through my vented hood and on to my windshield. I know, i know,.... get to the point. well the tear down didnt reveal very much at first, head gasket was good, o-rings on the block still looked good, head studs all approx. the same loosening torque necessary. Did perform leak down test on the engine before removing head and found 1 - 35-40psi, 5 30-35psi, 3 40-45psi..... wait is my brand new leak down tester broken, the engine did run and still made decent power..... 6 - 40psi 2 - 92psi..... okay tool not broke, 4 - 15-20psi. whoa not good. Poured some oil in to the cylinders and ran another test and this time i had a seriously hard time finding TDC, when i did find it leak down was as high as 95psi on all cylinders except for 4, but all would bleed off and you could hear the oil draining down in to the bottom of the block. pulled the head off and found there was some fragment impact indentation on the pistons and the flat part of the head. Some grooving in the cylinder walls as well. finally pulled the pistons and found that cylinder 2 was okay but the rest had verying degrees of piston ring land failure. 4 being the worst and was actually missing pieces of the ring land. the rest were cracked but all pieces were still there. Now im just wondering what you guys think the actually cause of the failure was. keeping in mind this engine was 480,000km old when rebuild but everything was checked and spec'd and all was perfect. this is also not my first m30 build and lastly, yes i did beat the shit out of this car and it did run 28psi for a while till the tranny melted to itself. i really thought the pistons would handle more but im interested to hear what the engineers have to say... brad.... lol...

[bornagain]

PS if anyone near me has a m30b35 for sale or b34 let me know thanks. lol

[Shawn D.]

What would cause.....?

A vague thread title? Could be lots of things.

[Kyle in NO]

Poor tuning.

[T_C_D]

Most likely detonation.

[bornagain]

yes vague title but causes curiosity... i really didnt think i heard detonation but then again with an engine/turbo/exhaust setup as such used as such it can be hard to hear over top of it, however not my first megasquirt build and not my first turbo m30 build, most maps were started from my known good car and spark was conservative. And know good car has been going strong for 40 - 50,000 km which isnt a ton but i dont drive these all that much. [https://instagram.com/p/2kUXNvPlU3