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Discussion Starter #1
been searching for a few hours now and i still need some advice or knowledge dispensed to me.

so here it goes. i have a set of ycp pm3 pistons that i'd really like to use in my d16 build (-1.50mm dome and 30.70 comp height)

if i used them in my d16y7 block (non vtec valve reliefs should be fine) i thought about milling .70mm off the top of the dome because that would have them sitting at the deck like a normal p2e y7 piston (-7.4mm dome and 30.00mm comp height) ....all that would change would be a considerably flatter dome...it would tight as hell.

i have a .040 off the head and bisi level 2 cam im going to use so im sure it would be tough to get the clearances i need but i just want to see what you all think of this idea and if it can or cant work any one reason. (is it safe to mill pistons? ring issues?... etc)

any and all info is welcome

thanks
 

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Discussion Starter #4
the compression on my build would be like 12.67 or so with the pm3's at the current compression height...i only have 93 octane available to me. is that truly "suitable" for a daily driver set up? a good tuner is at my disposal on this build.

and that set up will also put me at -.070 inch of piston to deck...i would have to run a thicker headgasket to gain some clearance anyway if i decide to use these pm3's.
 

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Discussion Starter #5
and thanks for that first reply bone, i didnt know if anyone wanted to tackle this issue initially
 

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Brokedick Millionaire
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PM3 will be .028 out, so running a .060 HG allows .032" clearance.

I plan on doing this with a Y8 head, approx 11.5:1 compression, 92-93 pump.
 

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Discussion Starter #8
the head i am using is milled down .040 so i have additional compression and clearance issues to grapple with.
 

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Discussion Starter #10
I run Endyn Rollerwaves 12.7:1 On 92-93 pump gas 9k RPM no problems
so at least fuel quality wouldnt be that big of a problem for me...
tighter quench probably allows for slightly less octane fuel being necessary
 

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Discussion Starter #11
valve reliefs will be the main issue then...
i thought that wouldnt matter because all the reading i did on PM3 pistons being used was involved with using vtec heads on a non vtec piston so the reliefs needed worked on.

i guess that may be the case here as well...
 

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1988 Honda CRX
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You should certainly clay the engine if you have seriously interfered with things that effect piston to valve clearance.

You have the wrong piston for the head, you have 0.040" off the head and you have a modified cam and the cut to the head not only puts the valves closer to the piston, it also changes the valve timing which puts the inlet valve closer to the piston.

This certainly requires you to measure things and machine the valve reliefs if necessary.

Cutting a head not only puts the valve lower, but also moves it sideways to ward the bore relative to the valve notches in the piston when at TDC.
 

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Discussion Starter #14
geez thats brutal...serious kiss carnage! sleeves went too....

i want the opposite of that!
can the valve reliefs be machined out to provide adequate clearance? i have heard of people doing that with other set ups.

if i had to do machine work on the pistons i was planning on sending them to be thermal coated by swain tech race coatings just to be safe.
 

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Discussion Starter #15
yeah for sure pat...good info as usual. i would never have known that cutting the head moves the valve sideways at TDC

i would definetly measure and clay the motor before going ahead with such a build.

would a custom headgasket thats a good bit thicker (as if .060 wasnt enough) buy me more room? Im thinking that the machine work on the piston is going to be necessary no matter what.
 

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Discussion Starter #17
it seems like a monster cam could do that kind of work....

i have another option...i do have a set of oem pm3's in my friends basement so im going to measure the depth and outside circumference of the valve reliefs then measure them against the YCP pm3's i have. the depth on the ycp pm3's looks to be a slightly more from most pictures i have seen but i could be wrong. or ill just put the honda pm3's in and clay it to see how the clearances are.

i still think the pm3 on a d16 rod would make for a nice set up if you could get the clearance and tune right.
 

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Brokedick Millionaire
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It is my plan for my CRX.

D16A6 with 75.5mm PM3's, .060" Cometic HG, Y8 head.

Right now I'm at either 10.3 or 10.7:1 compression, this would put me at 11.5:1 with a fresh bottom end. Then likely upgrade the camshaft in hopes for 13.9 ET NA.

Then maybe a 75 shot for good measure :)
 

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Discussion Starter #19
thanks for the info on this bone, youre always a great source of help with any of the bright ideas i come up with. and youre polite when they arent so bright which is prob 99% of the time. mucho appreciated.

that A6 would be a fast ass set up...an agressive delta or bisi nitrous cam on a good tune and it would own.
 

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Discussion Starter #20
well heres some simple math on my build:
d16y7 block w/ pm3 pistons hits .028 inches above deck which = .71 mm above deck
head work milled .040 inch off = 1.01mm

total removed = 1.72mm
head gasket .060 in = 1.52mm

-1.72mm taken away
+1.52mm added

so:

this set up would yield pm3 pistons hitting 0.20mm above deck (- on the zeal calc)

variables: zeal calc being infallible
rod stretch @ high RPM
head gasket thickness after torqued down

i need help there, i dont know how much to account for or whether the MLS style head gasket will compress?

anyone know what the best way would be to account for the higher lift of the new bisi level 2 cam?

trying to make progress on this one
 
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