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Discussion Starter #1
I want to do away with my tired p28 pistons and exchange them for a higher compression piston. Can anyone direct me to a piston that requires no modification to the block and isn't going to have a valve clearance issue inside of a d16z6. I would prefer an easy direct replacement.
 

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well this will require milled LS rods(but no bushing needed), or straight up 98-00 GX rods; PDN pistons...which have a smaller dome than P29s but still bring compression close to 12:1. If not that then your next option is PM6 pistons which need no mods and brings compression close to 10:1
 

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Discussion Starter #3 (Edited)
What does (milled) mean? Bushings? And where do the GX rods and PDN pistons come from? Are they raped from other motors? Will i need new rods for the installation of the pm6 pistons? Sorry for being such a noob and asking so many questions.
 

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GX=from 98-00 Civic GX. Milled meaning the rods need to be shaved about 1mm on each side. LS rods have a 21mm pin end, so does the 98-00 GX. When using LS rods with other D-series pistons, you need a bushing that brings the pin end diameter down to 19mm.

With PM6 pistons, you can use your stock rods.
 

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rods will be fine sir....pm6 babe
 

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im gonna go ahead and steal this saying from transzex.. " vtec valves meet with non vtec pistons "

pm6's dont have the vtec valve relief so be careful when using them.. results can be pretty smashing
 

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Discussion Starter #8
Thats one thing that i was worried about. I dont want to have to adjust the valves. What do people do about the valve clearance anyways? Any other pistons that will give higher compression that will work with stock rods and wont have any valve clearance issues?
 

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The PM6s are dished; there are people running P29s in Z6s and getting away with it; so I'd say it's safe to assume it'll work(given you don't have a huge cam).
 

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its funny.. but p29's actually have a nice valve relief for the vtec head... but heres a pic ( im using it from a thread that TRANSZEX posted it in but i cant find the thread now ) but anyway heres a pic of what happens with pm6's and vtec

where the red arrow is.. where the valve hit and it demolished the other piston


heres a pic of my old p29's


and heres a bad pic of p28's
 

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Discussion Starter #12
Im trying to make a final decision on rods and pistons. Anyone have any horror stories about stock rods and p29's? Anything bad at all before i start buying and swapping?
 

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how big of lift and duration of cam was used in the murder of that pm6 equipped vtec combo?
 

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how big of lift and duration of cam was used in the murder of that pm6 equipped vtec combo?
apparently stock.. you see where the valve hit where i pointed the arrow to??? theres no relief right there... it will hit sooner or later.. my friend did a mini-me d15b7 block y8 head and a d16a6 paper headgasket so it would lower the compression and hopefully lift the head enough so the valve wont hit..

he got lucky.. but again he never really took it over 6500 and he didnt race it that much idk if it makes a difference.. or if he just got really lucky by using a thicker headgasket idk
 

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hmm...(clay your build matt clay it,cmon.~oh cmon it will be fine, thousands have done the z6 block, a6 pistons-rods, and y8 head stock cam with no issues~i will come back and haunt you with i told you so thoughts..~ok ok when i get my 1 y8 headstud in ill engage vtec solenoid and manually check for any piston/valve interference..happy now?)
 

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The pic of the demolished pistons are PM3 pistons, not PM6; which are flat top and have a higher compression height. Although, it does show the reliefs are in different areas

Anyone with D16A6 mini-me's can chime in? Since they are running PM6s with VTEC.
 

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I have a new set of P29's with rings and pins they are +.040...
They are a direct fit on stock rods and have the right valve releifs..

I changed my mind and went to high end rods and pistons during my buildup.
 

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I have a new set of P29's with rings and pins they are +.040...
They are a direct fit on stock rods and have the right valve releifs..

I changed my mind and went to high end rods and pistons during my buildup.
this isnt the for sale thread.. read the sticky
 

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The pic of the demolished pistons are PM3 pistons, not PM6; which are flat top and have a higher compression height. Although, it does show the reliefs are in different areas

Anyone with D16A6 mini-me's can chime in? Since they are running PM6s with VTEC.
I'm with a D16A6 and P08 VTEC head (Zex Stage 2 cam). Revved all the way up to 8000RPM with a Skunk2 chipped ECU without any issues.
 
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