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Discussion Starter #1
Hi, fellas!

Wanted to share some pictures with you..
These are one summer driven YCP Vitara pistons. They are 75.5mm and were put in freshly bored and honed block. Car is running E85 and was about 330 hp flywheel and was tuned with Crome pro. Pistons were installed as always - arrow facing flywheel. Block was taken apart because of spun rod bearing (#3).

My buddy's Vitaras have the same cracks and as here they are all on the one side of pistons (intake manifold side)!

Take a look at those micro cracks and don't forget to check your used Vitaras. :)

All 4 pistons have these cracks!


You can check other pictures here ->
http://i56.tinypic.com/2565lis.jpg
http://i53.tinypic.com/2zzjl1d.jpg
http://i52.tinypic.com/2r77tb9.jpg
http://i52.tinypic.com/2zs679t.jpg
http://i56.tinypic.com/15f2e5x.jpg
http://i51.tinypic.com/vqi9nt.jpg
http://i51.tinypic.com/2ldc85l.jpg
http://i53.tinypic.com/30rkxmb.jpg
http://i51.tinypic.com/14bn5np.jpg
 

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damn dude that sucks ive got the same thing but ive only had the motor running 10min total hope mine stay together.
 

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Could it just be a bad batch? My buddy's old setup was running 300whp - 400whp for 3 years with 75% of it's running time at the track and it still ran strong. I'm thinking if all of the pistons were like that, then wouldn't his setup fail already. He ran 400whp+ at 28PSI with 9500rpm shifts. He eventually sold the motor, but I'm positive it's still running till today.
 

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Could it just be a bad batch? My buddy's old setup was running 300whp - 400whp for 3 years with 75% of it's running time at the track and it still ran strong. I'm thinking if all of the pistons were like that, then wouldn't his setup fail already. He ran 400whp+ at 28PSI with 9500rpm shifts. He eventually sold the motor, but I'm positive it's still running till today.
THIS
 

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My civic
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Hrmm... i was under the impression that vitara's are the way to go for our d series. This is no good. Does anyone else have this issue?

I noticed in this pic http://i52.tinypic.com/2r77tb9.jpg that there look like there is an impact mark just above the crack. Bad casting or was it damaged pre-install
 

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Hmm, all the cracks are in a corner/point. I wonder if this would have happened if that corner were radiused/chamfered.

 

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FYB or FIU tune, pick 1
95 Del Sol Si
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If the crack doesnt get any worse i believe theyd be ok to re-run them, but for the price of brand new ones most people would opt for a fresh start. Also where did you get these fj or p2p0, or even ebay?
 

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Hrmm... i was under the impression that vitara's are the way to go for our d series. This is no good. Does anyone else have this issue?

I noticed in this pic http://i52.tinypic.com/2r77tb9.jpg that there look like there is an impact mark just above the crack. Bad casting or was it damaged pre-install
The is definitely an impact mark of some sort. You can tell by the deformation that occurs around it.

what was your P2W clearance?
This.

So they're devoloping small cracks, but do they just stop there?
Or will they continue to crack (and then break)?
Would it be safe to continue running the pistons like that?
They are going to continue to crack. I wouldn't suggest using them after spotting a crack like that.

Hmm, all the cracks are in a corner/point. I wonder if this would have happened if that corner were radiused/chamfered.

Removing any sharp points on a highly stressed part is very important.
 

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doesnt matter where they came from because they are ALL YCPs.

there have been close to a handful of people have this problem, i'm pretty sure JFK had a set do this but they actually broke.

in my opinion its pre-ignition, slamming the piston before TDC. its awfully funny that everyone thats had this problem also had rod bearing problems (pre-ignition slams the top of the piston shocking the rod bearings)...

how many thousands of people run YCP vitaras without a problem?
 

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Its more than likely a bad batch with all the hundreds if not thousands of people including myself that have run vitara's and not had them fail due to issues like this. it would seem to be isolated possibly. The pistons have propelled 9 sec cars and countless low 11 and 10 sec ones.
 

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doesnt matter where they came from because they are ALL YCPs.

there have been close to a handful of people have this problem, i'm pretty sure JFK had a set do this but they actually broke.

in my opinion its pre-ignition, slamming the piston before TDC. its awfully funny that everyone thats had this problem also had rod bearing problems (pre-ignition slams the top of the piston shocking the rod bearings)...

how many thousands of people run YCP vitaras without a problem?
I would agree. Combine that with loose piston to wall clearances, and you have a recipe for a piston getting rocked about a lot.
 
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