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compresion fail...

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Old May 22, 2010 | 04:36 PM
  #1  
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Default compresion fail...

finally getting around to getting my car running again after a year and a half. when i left it, it was smoking pretty badly when running at almost all times. oil smoke.

turbo DEFINITELY needed a rebuild as the shaft play was bad enough to have the compressor housing have some light scoring from the wheel, so that's been sent out, but i was hoping the motor itself was ok. finally gt around to doing a compresion check today. i was happy until i hit cylinder 4...

as you can see form my sig, it's a 1.6 greddy based setup with a begi DP and MSI. ran great at 14 - 15 psi, but the urge to crank it up a bit, (to 17'ish, maybe a little more) may have been thr straw that broke the camel's back...

could be valve related, or ring related, i suppose... might as well pull the head next time i can work on it and see what's up.

FML.

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Old May 22, 2010 | 04:38 PM
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Ouch. I drew the line at 15 psi with my Greddy. Upgrade to a 1.8!
Old May 22, 2010 | 04:40 PM
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Did you have a dual feed fuel rail? I'm guessing detonation caused the damage in #4.
Old May 22, 2010 | 04:46 PM
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negative on the dual feed. i hadn't thought of that though.. 1 - 3 plugs looked pretty rich, though, and similar to 4... i didn't see anything BLATANTLY indicating det on 4... btu i guess i'll get a picture of it when i yank the head next weekend.
Old May 22, 2010 | 04:51 PM
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well if ya need anything I've got some stock internals and new rings I didnt use LMK
Old May 22, 2010 | 04:55 PM
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i'll keep that in mind. pm me a price shipped so i can run down my options this week and make a decision?
Old May 22, 2010 | 05:02 PM
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What do you think you might want? I've got a set of rods with good pistons attached and the bearings look good still you could possibly reuse them
Old May 22, 2010 | 06:20 PM
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when my car leaned out on nitrous valve was the first to go. i lucked out and bought a "replacment head" on ebay for 150 bucks and it showed with hks 256s in it 14.9whp gain with no other mods.
Old May 24, 2010 | 10:49 AM
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looks like the plan is to pull the head and hand it over to my fiance's dad so he can bring it to a machine shop he works with (he owns a used import dealership) to check out. if there's anything off-looking, they'll refresh it with oem-spec stuff and i can slap it back on with some arp studs and check the comp again (assuming the cylinder bores look ok when i pull it). if it still doesn't show decent comp, then i'll build the bottom end with some m-tuned or belfab rods.

my guess is the more likely culprit is the valve guides/seals, since all my plug wells had oil in them that looked like it had been forced through the o-rings on the valve cover side, and adding a tbsp or so of oil to cyl 4 yielded a 120 rather than the 90 i got when i tested it dry.

thoughts on this plan?
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