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bring ur pistons to ur autosupply..
ask for our local VTI rings.. i think this is the same..

but its best to have the pistons with u.. some autosupply stores have a few sample pistons.. and u can check the thickness with the,...

im sure however theyre not the same as pm3
 

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hehehe no prob...

or if u have a caliper measure the thickness of the 1st/top ring 2nd/bottom ring

and the total thickness of the oil control rings, aka 2 rings and expander..

and u can check what they have at the autosupply
 

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Discussion Starter #5
OMG!

FUCK!!! I just removed the piston from the block. The ringland is broken. Should I replace all of them or should I just replace the broken piston? I knew I had a compression leak from #4 so I thought it was the rings, then when I pulled it out the ringland was shit.
 

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FUCK!!! I just removed the piston from the block. The ringland is broken. Should I replace all of them or should I just replace the broken piston? I knew I had a compression leak from #4 so I thought it was the rings, then when I pulled it out the ringland was shit.
get rid of the p29's get some flat tops and mill the head/block for more compression.
 

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Discussion Starter #7
I would man but money isn't looking to good these days. The 3 other cylinders have 250 psi each with the crower stg. 3. And when the compression was all the same that shit was pulling harddd. I'll post some pics of the broken ringland so I can get some opinions of what went wrong.
 

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while the flatop idea and milling is an excellent one..

id suggest.. either getting a set of p29's (4) and re install the new sets..

this is most def a tune issue.. possible too much timing to cause ring land cracking etc..

r u using Petron Blaze? our pump gas is pretty good ,

when i was first starting the tuning part.. what i did was pull timing everywhere (i know it wont run best but.. its safer) and try to tune a/f as best as u can..

forgot ur build details..

but we've gone as much as 0.020" mill on z6 heads, with p29's and just a crower2

hope that helps..

hit me up if u need help man...

btw what size p29's r u running?
 

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Discussion Starter #10
Doesn't it look pretty new still? I'm sure I installed everything properly and measured all clearances before hand.









I'm gonna pull out the rest of the pistons and see if they got cracks in em or not.
 

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Discussion Starter #12
well the 3 other cylinders had 250 psi on the compression tester. this one had below 100 psi. and the cylinders have slight scuffing but nothing that grabs my fingernail so I think it's still good.
 

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well the 3 other cylinders had 250 psi on the compression tester. this one had below 100 psi. and the cylinders have slight scuffing but nothing that grabs my fingernail so I think it's still good.
was it easy to tell that one cylinder was low on compression? how did it start? im wondering if i have low compression on a few cylinders because of bent valves.
 

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Discussion Starter #14
yup. sounded like it was running on three cylinders. startup showed a noticeable difference cause it sounded like it would skip a cylinder and then start. I pulled out all the pistons today. 3 of the pistons are ruined and have cracks in the ringland. specifically 1,3,4 pistons are busted. is your compression alrite so far with your motor cervan?

The way I checked if my valves were sealing is that I flipped the head over so the chambers were facing up and I poured gas into the cylinders. I used old spark plugs to close up the spark plug hole. I just looked for signs of the gas seeping thru and apparently all were fine except for one. So I'll be lapping that agen.

BTW I remember reading that p29's are notorious for breaking ringlands. I'm not sure if it was a brand thing or tuning thing but all the cracks on my pistons were all in the same places. My pistons by the way are Nippon of America. I'm gonna order the YCP's this time around because they seem better built. I'll post my timing maps so you can take a look.
 

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Discussion Starter #15
Here are my maps from eCtune. My setup btw is d16y5 block, p29 pistons, d15b head, crower stg. 3 cam.

These first 2 maps I ran for about 600 km and is the reason WHY I messed up my pistons. I really don't know how to tune timing hehe.

Stock low map


Stock high map


This is my second map that I ran for ~50 km and it was pulling HARDD, the car ran WAYYY better on these 2 maps.

Modified lo map


Modified hi map


yeah I realized that I didn't just bust my HG, I also busted up my pistons. At least the block is still ok.
 

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this is most def a tune issue.. possible too much timing to cause ring land cracking etc..
Sounds like SOHCitTOem has figured that out too. I know what those maps are, but have never paid enough attention to know what needs to be changed...

Now that's scary. It's no wonder you didn't have any compression.

My pistons by the way are Nippon of America. I'm gonna order the YCP's this time around because they seem better built. I'll post my timing maps so you can take a look.
Everyone seems to swear by the YCPs when it comes to Vitaras. Of course you'll never know if they're better than the Nippons unless you reinstall tham and keep the same tune.
 

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well id still say the timing is high or tune issue...

just thinking logically.. one shouldnt upgrade to a tougher piston due to a mistune?

but hey gid, its all good.. first build, first tune... ur doing what most dont even think of doing hehe..
 

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Discussion Starter #20
Well I'm not saying its nippon's fault the piston cracked but I intended on getting the YCP's even before I bought the Nippon's. Only reason why I went with the Nippon's cause FJT didn't have the YCP's available.

Thanks for the encouragment. It's actually been pretty tough man and now I can see why people pay so much for a good build. It's ALOT of work especially for a first timer like me.

The head has not been milled, it's only resurfaced to make it flat. The weird thing about this is that there was no audible knock AT ALL. Even with my ghetto det. cans. I would hear a tap noise but I suppose that was the valves making all the noise from the stg. 3. Does the timing still look to advanced [email protected]? What kind of AFR's should I be aiming for? SO far I've tuned to target 13.9-14.8 AFR throughout the RPM range. Is this still too lean for N/A?
 
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