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Old 10-20-2012, 11:02 PM   #1
2011boostdwrx
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Default what do i do second SB cracked cylinder

I am really frustrated I have the third SB sitting on the garage floor ready to drop in the forged pistons and go, but this is also a 704 series. as you can see in the pic, the cylinder cracked on the dyno @ 23.5 PSI HTA68 @ 23.5 psi 350 whp with meth.

The first block went with the ringland, second now with the cracked cylinder, what do I do?

I now have a BNIB 20GTX STS Turbo, Equal Lenght Header, on and on. Car is was protuned with AP, there was no overheating or knock during the dyno and we were running 1:1 meth/water.

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Old 10-20-2012, 11:14 PM   #2
jesterjames
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Stock bore?
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Old 10-20-2012, 11:34 PM   #3
sense of nature
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Wow **** luck man!
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Old 10-21-2012, 09:47 AM   #4
2011boostdwrx
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Yes stock bore, it was a brand new SB from Subaru. I am told the 704 series, now all I can get new have been having these issue something with the casting. But if cosworth is using these blocks for thier builds why the hell wouldnt they crack too?
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Old 10-21-2012, 10:26 AM   #5
FuJi K
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Your tune must be to powerful.
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Old 10-21-2012, 07:52 PM   #6
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the only thing that is going to split a cylinder like that is too much cylinder pressure(due to knock whether you believe it or not) or a head gskt failure which allowed coolant to get into the cylinder in a large amount and caused a small amount of hydrolock which split that cylinder.
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Old 10-21-2012, 10:25 PM   #7
2011boostdwrx
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Yeah, but the piston is fine, not a thing wrong with it, it is just the cylinder wall. I did smell coolant during the brakin milage, could it be that the head gasket was bad from the get go? I was assured there was nothing wrong and it was normal.
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Old 10-21-2012, 10:37 PM   #8
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Quote:
Originally Posted by 2011boostdwrx View Post
Yeah, but the piston is fine, not a thing wrong with it, it is just the cylinder wall. I did smell coolant during the brakin milage, could it be that the head gasket was bad from the get go? I was assured there was nothing wrong and it was normal.
Is heads warped?

Also are you sure your meth system isn't leaking or sphioning?
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Old 10-21-2012, 10:54 PM   #9
john 1badSTI
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remember water or coolant does not compress like air so if either got in there in excess it will break the weakest spot thus the cylinder wall at the case bolt cutout.
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Old 10-21-2012, 11:15 PM   #10
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I was told the heads are fine, the meth system is the HSF-2 from aquamist with the check valve installed in the engine bay, I doubt there would be any siphoning going on.
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Old 10-22-2012, 12:00 AM   #11
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2.5 it and be done with it
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Old 10-22-2012, 12:11 AM   #12
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Quote:
Originally Posted by kj15991 View Post
2.5 it and be done with it
That is a 2.5
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Old 10-22-2012, 12:14 AM   #13
bheinen74
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solution,
use a ej22t closed deck block.
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Old 10-22-2012, 12:22 AM   #14
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i forgot about the 2.5 wrx's. ej22 it i second that closed deck you wont have the problem again
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Old 10-22-2012, 12:39 AM   #15
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I would look over the whole setup again to see of there are any flaws. Making sure you didn't run out of meth on the dyno, checking hoses, etc.

I don't see how you're blowing up blocks when there are cars running 9sec in the 1320 on factory sleeves.

Check your meth setup over.
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Old 10-22-2012, 12:51 AM   #16
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You didn't by any chance floor it in 5th or 6th gear when it went did you? I have to ask because such turbos can make quite a bit of pressure at very low rpm in a area not fully "mapped" out by the tuner or it simply started to knock and since you pass through the rpm range so slowly it eventually raises EGT sky high if the knock system reduces timing sometimes producing more knock.
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Old 10-22-2012, 12:55 AM   #17
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Ugh. I had the same failure at this spot on a block out of a 2009 STI that had ringland failure. Machined and reinstalled forged pistons and then cylinder crack just like yours.

It failed along the "scallop" for machining the case bolt clearances.



Oh and it was on cylinder 4.
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Old 10-22-2012, 08:35 AM   #18
2011boostdwrx
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So what did you do? And that is a 704 series block casting correct? How much WHP when it went?

IF I go EJ22, does that mean I will be at 2.2 liters instread of 2,5?
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Old 10-22-2012, 11:44 AM   #19
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Yes, an ej22 is a 2.2l, you can also put a 79mm stroke crank from a 2.5 and and whatever else is needed and end up with a 2.35l.
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Old 10-22-2012, 03:45 PM   #20
2011boostdwrx
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I am talking to outfront motorsports and they a building closed deck 2.5L motors. This is the route I may go need to talk to my tuner tomorrow.

http://www.outfrontmotorsports.com/s...ort_blocks.htm
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Old 10-22-2012, 05:59 PM   #21
john 1badSTI
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^^^^That is just a block girdle and will not make the block really that much stronger at that spot where they all crack.
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Old 10-22-2012, 06:33 PM   #22
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this is what you need.
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Old 10-22-2012, 08:10 PM   #23
2011boostdwrx
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An EJ22T? I cant find any and if you do they have tons of milage on them.
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Old 10-22-2012, 08:23 PM   #24
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Anyone familar with outfront motorsports closed deck block inserts?
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Old 10-22-2012, 08:29 PM   #25
john 1badSTI
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I would recommend sleeving instead of the block guard for strength.
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