Hey guys just planning out my summer build and had a new idea. I'm going forced induction and have most of my parts. I'm going to have a y8 head on a D16y7 block, I'm also assuming the head was milled about .020" since it's been rebuilt and they probably have taken some off of it. I'm going to use the zealautowerks calculator to estimate compression ratios. With my stock rods and pistons I'll have an estimated compression ratio of 10.44, this is a little higher than I'd like for a DD turbo.
I got to thinking and figured if I run some eagle rods and vitara pistons <<(planned setup). This would give me the low low compression ratio of about 7.95 and since this is lower than ideal I would like to deck the block. If I can mill .065" off the block that will raise the compression right to around 9.0, which is where I would like to have it.
This leaves me with the question of how much can you deck the block??? Is .065" gonna be fine? How about .080" or even .1" ???

 

I would not deck the block to raise compression. I would look at other methods such as differnet pistons or thinner headgasket. If you need to rebuild you wont be able to deck the block or risk having the pistons out of the hole. Plus the tbelt will never line up. Youll need adj cam gears, trust me I know.

 

ah yes of course I never even thought about the timing belt not being able to line up....even though it seems so obvious now
thanks

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by civicjoe &raquo;</TD></TR><TR><TD CLASS="quote">ah yes of course I never even thought about the timing belt not being able to line up....even though it seems so obvious now
thanks </TD></TR></TABLE>

yeah i deal with that , and it sucks

 

so here's the situation. I have a pretty much brand new y8 head that's been remanufactured. When I put it on the y7 block my compression is going to be about 10.45. I want to rebuild with forged rods and pistons.
So here's my choices:
Rods:
forged rod...eagle...scat...etc... same length as stock.
fjdistributors.com custom length forged rod.....longer than stock.
Pistons:
forged pistons...same as stock
vitara pistons.... are gonna lower my compression a lot
So....
#1 forged rod + vitara = too low compression
#2 forged rod + forged pistons = too high compression
#3 custom rod +vitara = same as choice #2

Now I've basically talked myself into being confused...

I've also been using different compression calculators and they vary A LOT when I put the same setups into them.

EDIT: I'm sure I'm missing something here so if anyone wants to point it out your more than welcome.

 

Go with the low comp pistons and here are your options
1.) look for a thinner head gasket
2.) milll the head, not the block for same affect
3.) look for valves that raise the comp
4.) all the above

Or dont waste money on custom rods and cheap vitara pistons but get standard rods and custom pistons.