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Discussion Starter #1 (Edited)
Hi.

I'm building a d15-z6 mini-me engine.

I have a complete d15b2 block, d16z6 head, and spare PM7 (dohc ZC) pistons.

So, i'm trying to figure out what pistons to use.

I will probaly be using a akmee type-r or crower stage 3 cam. And I am aiming for about 11,5 CR.

I've been using these two CR calcuators:
http://www.knology.net/~jediklc/dcalc.htm
http://www.zealautowerks.com/dseries.html

Seems like complete B2 block, two layer gasket and z6 head i about 10,5 CR. Is this correct? I've read 10,1 elsewhere.

According to the zealautowerks calculator, b2 block, b2 rods, pm7 pistons, two layer gasket and z6 head will be 10,8. Does not this soud a bit low? Since there is such big diffrence in the pistons?

Some how i seem to get a CR of 10,3 with PM7 pistons on the knology.net calculator, that can't be right!?

Anyone have better info on this? Need help here..
 

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Discussion Starter #2
Looks like it is right that the CR is lower with PM7 pistons. (lover piston height).

So i'll guess i will go for stock B2 short block, two layer gasket, and mill the head one millimeter (0,04.in). Then i will be about 11,8 CR.

Does this sound correct?
 

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The piston-to-deck height on knology makes the calculations a little off(you'd have to calculate it yourself to correct the problem). With the PM3 pistons and the VTEC head, I wouldn't really want to mill the head. IIRC, Bone posted a pic of valve-piston contact when using the PM3 pistons. You'd probably be better off with the PM7 pistons and milling the head or block slightly.
 

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Discussion Starter #4
ahh, i see. that's werry interesting..

On knology the CR goes down with PM7 pistons (according to my calculations). And on Zeal it goes up.. And i have read somewhere that the CR gets realy low with PM7 pistons in a D15 block (with normal d15 rods).. Getting a little bit confused here :p
 

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different pin heights means the PM7's into a D15B2 is not worth it.

only .2 rise in compression ratio from the piston swap alone.
 

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Discussion Starter #6
.2 is better than .0 :) And if the ZC pistons is better for valve clerance, why not use them? Remeber, they are just laying around, so why not use them.

Do anyone know for sure what the CR will be with ZC pistons in a d15-minime?

Is it possible to get over 11:1 with only stock parts and milling the head?
 

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Discussion Starter #8
Yes, i know. The poblem i that I can get the Z6 head for free, and a Y8 head is hard to get a hold of over here, and will cost at least $500.
 

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Discussion Starter #9
zealautowerks:
d15 block, pm7 pistons, y8 3-layer gasket, z6 head milled 0,035in = 11,5:1 CR.

I cant see why this wont be "safe". People run over 12:1 CR on Z6 engines with stage 3 cams, and i don't see the diffrence. Except for maybe the piston profile, but as far as i know PM7 pistons in Z6 engine gives 12:1 CR, and that works fine.
 

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Discussion Starter #14
Yes, i read it. I was not sure if i could trust only one person, when the two calculators gives two diffrent answers..

But if you are poitive that the PM7 gives .2 higer CR then that is OK.. Thank you for the help Mista Bone.
 
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