Datalog shows 15,000rpm: crank pulley shears and... - Page 3 - Miata Turbo Forum - Boost cars, acquire cats.

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Old 02-17-2010, 05:58 PM   #41
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Which is why I still say trash it all! Junk yard engine is a gamble, but it's also cheap and hopefully not all scratched to hell inside.
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Old 02-17-2010, 08:12 PM   #42
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Which is why I still say trash it all! Junk yard engine is a gamble, but it's also cheap and hopefully not all scratched to hell inside.
So throw away a fully built motor?

I think you guys are paranoid. Even if the entire motor was "compromised" why not slap it back I and crank the boost until it dies?

The head I don't care about because I have a spare built 99 head i've been waiting to put on.

Why not just tear it down, hot tank everything and get new bearings and an oil pump (got a spare one anyway aswell).
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Old 02-17-2010, 08:16 PM   #43
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So throw away a fully built motor?

I think you guys are paranoid. Even if the entire motor was "compromised" why not slap it back I and crank the boost until it dies?

The head I don't care about because I have a spare built 99 head i've been waiting to put on.

Why not just tear it down, hot tank everything and get new bearings and an oil pump (got a spare one anyway aswell).
If you didn't overspin it and you are comfortable with the fact that it could blow, just run the ******.
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Old 02-17-2010, 08:21 PM   #44
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Yeah, those look fucked up. The bearings I pulled out of my trashed motor a couple months ago looked significantly better than that.
Pics of said bearings?

Bearings are designed to wear when faced with **** like this in order to protect the crank right. So say the oil pump is fucked, replace it, cam journals are fucked, replace the head, essentially do a full rebuild, it's not like I'd be the first person to have metal eat some bearings.
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Old 02-17-2010, 08:25 PM   #45
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Yeah. Them's be a bit fuggly on the bearings. Mine looked like this at 110k miles.

Notice they don't look like they were scratched to **** with a 40 grit sandpaper wheel.


That's a rod bearing though right. My old rod bearings looked like that but the mains were alot different, they look like the mains of my current engine, less shiny mostly but still have longitudal lines in them (one has a big cut down the center of it too)
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Old 02-17-2010, 08:51 PM   #46
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As long as all your clearances spec out I say new gaskets/bearings/rings and reassemble...but with '99 head.
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Old 02-17-2010, 09:25 PM   #47
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Quote:
Originally Posted by dc2696 View Post
So throw away a fully built motor?

I think you guys are paranoid. Even if the entire motor was "compromised" why not slap it back I and crank the boost until it dies?

The head I don't care about because I have a spare built 99 head i've been waiting to put on.

Why not just tear it down, hot tank everything and get new bearings and an oil pump (got a spare one anyway aswell).
n/m, I wasn't aware it was built. Since it wasn't an over rev, just a full rebuild would suffice for my nerves. Check cam journals well and go for it.
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Old 02-17-2010, 09:26 PM   #48
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That's a rod bearing though right. My old rod bearings looked like that but the mains were alot different, they look like the mains of my current engine, less shiny mostly but still have longitudal lines in them (one has a big cut down the center of it too)
Crank bearings were actually in slightly better shape than the rods.
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Old 02-17-2010, 09:31 PM   #49
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Ok Heres a BIG surprise:

My Rod bearings are FUCKED! Haha

3/4 rods spun and they are fucked up for sure.

Metal shavings plugged oil gallery, carnage insues, crank is garbage probably lol.

I'll take the rods in and see what they say about them, probably reuseable but definately need bearings. Crank can probably be turned and ground down, or I can use my spare crank, I'll get both looked at and choose the better.

Only rod that didn't spin the bearing was cylinder 4. The rest are just, well I'll post some pics lol
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Old 02-17-2010, 09:46 PM   #50
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Name:  photo-8.jpg
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All of them were squashed and scarred and gougded and just fucked.

And you guys thought my mains were all fucked up lol
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Old 02-17-2010, 10:14 PM   #51
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Fubar! Nice pics.
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Old 02-17-2010, 10:49 PM   #52
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Look at those scars!
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Old 02-17-2010, 11:08 PM   #53
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Could this all be caused by your damper coming off? I could definitely see it...
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Old 02-18-2010, 12:25 PM   #54
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Could this all be caused by your damper coming off? I could definitely see it...

Doubt it, the crank oil galleries are completely filled with metal, that's the cause of the bearings but what caused all the metal in the first place? Could be the oil pan metal, maybe it wasn't cleaned well after I ground it down and installed it. Or maybe it was something else...
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Old 02-18-2010, 12:28 PM   #55
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I think I just decided I will never buy a built motor.
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Old 02-18-2010, 12:32 PM   #56
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How does the oil pump look inside?
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Old 02-18-2010, 04:03 PM   #57
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does the 15k RPM number have something to do with the miata using a wasted spark system?

His rev limiter was 7800...2x7800 = 15,600
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Old 02-19-2010, 12:01 AM   #58
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FWIW I don't recommend buying someone else's built motor either. That mistake cost me about half a year and almost lots of $.

I'm very interested in the real cause of failure- if it was the dampener or if the motor was running "without any problems" and the dampener failure made you peek inside.

How does your crank look?

Also, FWIW I hit 10.5K RPM on my stock motor when I went from 3rd to 2nd @ 80mph. My tires locked up and it sucked. It was only for about half a second. Stock motor "survived" but I don't know what the interior crocodile alligator argh I mean what the engine internals look like yet.
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Old 02-19-2010, 12:05 AM   #59
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I'm very interested in the real cause of failure-
+1, I would love to inspect this block. Keep us updated.
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Old 02-19-2010, 01:11 PM   #60
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Quote:
Originally Posted by fooger03 View Post
does the 15k RPM number have something to do with the miata using a wasted spark system?

His rev limiter was 7800...2x7800 = 15,600
No, that doesn't matter.
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