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Fireindc's attempt to build a decent miata. (the search for more torque).

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Old Dec 20, 2013 | 11:30 PM
  #501  
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Double posting in my own thread. Anyways that's my fail so far in subaru land.
Attached Thumbnails Fireindc's attempt to build a decent miata.  (the search for more torque).-jto3d29.jpg   Fireindc's attempt to build a decent miata.  (the search for more torque).-ohlu8gd.jpg   Fireindc's attempt to build a decent miata.  (the search for more torque).-t0lmpve.jpg   Fireindc's attempt to build a decent miata.  (the search for more torque).-ixsxxdq.jpg   Fireindc's attempt to build a decent miata.  (the search for more torque).-k6w6pc4.jpg  

Fireindc's attempt to build a decent miata.  (the search for more torque).-4rbmlhl.jpg   Fireindc's attempt to build a decent miata.  (the search for more torque).-ionf3mg.jpg  
Old Dec 21, 2013 | 12:49 AM
  #502  
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That doesn't look like a newer 2.5, did you run the vin?
Old Dec 21, 2013 | 01:04 AM
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Originally Posted by 18psi
That doesn't look like a newer 2.5, did you run the vin?
It was, at least judging from the accessories. It had a drive by wire throttle body and a much beefier intake manifold on it, but i swapped everything over to what came on the foz. (some sensors, crank gear with different triggers, and the dr. side cam gear because it was different.).
Old Dec 21, 2013 | 11:47 AM
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Most people do leakdown testing at TDC. This assumes that cylinder condition on the entire stroke is the same as cylinder condition at TDC -- which is often an incorrect assumption.

Best to do both leakdown and compression testing. During a compression test, you monitor the pressure built by traversing the entire stroke.

$$0.02.
Old Dec 21, 2013 | 11:58 AM
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Originally Posted by hornetball
Most people do leakdown testing at TDC. This assumes that cylinder condition on the entire stroke is the same as cylinder condition at TDC -- which is often an incorrect assumption.

Best to do both leakdown and compression testing. During a compression test, you monitor the pressure built by traversing the entire stroke.

$$0.02.
Thanks for the insight. And for the record, i did do both leakdown and compression tests.

Leakdown resulted in good even readings, less than 15% across the board.

Compression test resulted in:

drivers side bank = 130psi (both within 5 psi of each other.
pass side bank = 160psi (both within 5 psi of each other)

This is part of why i suspected a HG initially, because the drop in PSI on the entire bank made me suspicious. Not so sure anymore! We shall see, off to go snowboard for now though.
Old Dec 21, 2013 | 02:12 PM
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Originally Posted by Fireindc
Leakdown resulted in good even readings, less than 15% across the board.

Compression test resulted in:

drivers side bank = 130psi (both within 5 psi of each other.
pass side bank = 160psi (both within 5 psi of each other)

This is part of why i suspected a HG initially, because the drop in PSI on the entire bank made me suspicious. Not so sure anymore!
This is a classic indication that something is up with the cylinders/rings. The leakdown result shows that the head/head gasket is fundamentally sound and the rings are holding compression at TDC. The compression result shows that something is wrong with the cylinders/rings on the passenger side bank as the entire stroke is traversed -- and whatever it is affects both cylinders -- which is kind of wierd -- maybe the block is cracked between the two? In for teardown pics!

Originally Posted by Fireindc
We shall see, off to go snowboard for now though.
Damn you and your snow and your mountains. Jealous.
Old Dec 26, 2013 | 07:34 PM
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Okay guys, sorry.. no pictures. But bear with me here, this is the synopsis.

So far, even just pulling the valve covers this is internally the cleanest motor I've ever disassembled. I got the heads off and they are in great condition, pistons look good from the top with minimal carbon, cylinders don't have a scratch on any of them and the hone looks brand new.

Also, the head-gaskets are fine. This is all good news, but it leaves me wondering WTF the problem is. I guess the next step is going to be to pull the pistons (which you have to do before splitting the cases anyways) and look further. I know the motor sat, so maybe I'm dealing with a stuck oil control ring.

I'm thinking about re-ringing it and leaving the bottom end. This motor clearly is around the 60k claimed miles, and I'd really like to slap it back together and run it seeing how nice it is internally. I'll get pictures tomorrow!
Old Dec 26, 2013 | 08:07 PM
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When do we get back to our regular scheduled programming?
Old Dec 26, 2013 | 08:23 PM
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Originally Posted by Erat
When do we get back to our regular scheduled programming?
Plas Juan.
Old Dec 26, 2013 | 08:25 PM
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Originally Posted by Erat
When do we get back to our regular scheduled programming?
Once I get this subaru out of the garage, so hopefully within the next month.
Old Dec 26, 2013 | 08:31 PM
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Sounds good. and don't split the halves unless you absolutely positively have to.
Old Dec 26, 2013 | 08:42 PM
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Originally Posted by 18psi
Sounds good. and don't split the halves unless you absolutely positively have to.
This was my thought, there should be no need to split the cases for a quick re-ring since the bores look so good.

Plus i'd like to get this thing up and running asap so I can focus on the BP.
Old Dec 27, 2013 | 04:42 PM
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True no point spending more money on it then you have to. Once you find the issue slap it back together and get that waste gate on your Miata so I can see what my car will be doing in a few months!
Old Dec 27, 2013 | 04:58 PM
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he already found the issue
Old Dec 27, 2013 | 05:09 PM
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LOL, yeah man. I'm completely ashamed but I'll own up to it. I'm a n00baru.

So, I basically hooked up the subaru PCV system backwards. I hooked up the valve cover breather directly to the intake manifold. SO i believe it was acting like a straw, sucking tons of oil from the valve covers and dumping it in the intake.

This explains why the airbox itself was clean, yet there was oil literally pooling on the intake valves.

Apparently this isn't a miata. Sideways valve covers, wtf?!

Last edited by Fireindc; Dec 27, 2013 at 05:23 PM.
Old Dec 27, 2013 | 05:19 PM
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Please notice the "fail" behind the coilpack there running to the pas side head.

Did not figure this out until i pulled the motor apart to find pristine internals, THEN of course i second guess my pcv routing.
Attached Thumbnails Fireindc's attempt to build a decent miata.  (the search for more torque).-ohlu8gd.jpg  
Old Dec 27, 2013 | 05:23 PM
  #517  
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Checked this thread for the first time in a week. See a subaru motor.

I'm so confused.
Old Dec 27, 2013 | 05:27 PM
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Wait... there's a different time to find out stupid mistakes other than when you have the entire car torn totally apart?
Old Dec 27, 2013 | 05:33 PM
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I just got lucky...fucked..to be able to find them that way!
Old Dec 27, 2013 | 05:36 PM
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Originally Posted by concealer404
Wait... there's a different time to find out stupid mistakes other than when you have the entire car torn totally apart?
I guess it's never a bad time to do headgaskets on a subaru



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