mattie_96

AFter searching on the net ,the compression ratio calculator is what I found that gave me a result of 10.8:1 or so of a CR. with a6 pistons, z6 block, and y8 head.
I was wondering if a6 pistons can be used in a z6 block with a d16y8 vtec head on top.
And if it is possible and will there be any piston-valve interference?

sanimalp

that is a complicated question. with a stroke of 90mm, a combustion chamber volume of 32.8cc, a piston dome displacement that reduces volume by 3.4cc, an oem head gasket for the d16a6 of .048in thickness and a piston to deck height of 0, you might have some clearance issues. the difference between this and a normal mini-me being the piston to deck height. you would lose .02inches by using the z6 block. i don't know how close the tolerances are on a normal a6-y8 mini-me swap, but losing that piston to valve clearance would make it worth claying for me. there is probably someone out there running the same setup though that could chime in on this subject. but unfortunately all i can do is the math.. which by the way gave me a compression of about 10.6:1

jlicrx

a lot depends on the camshaft - the closest the pistons come to the valves is at overlap, when both the intake valves and exhaust valves are slightly open at the same time - camshaft valve lift at TDC on overlap is going to determine the clearance - when claying a VTEC engine, you will somehow need to have the valves opening on the higher camshaft lobes in order to get the correct clearance - just turning it over without VTEC actuated will lead to false readings - might have clearance then, but when VTEC is actuated, you may be in trouble

D16A6 and D16Z6 (all D16) blocks have the same deck height of 212mm, so you don't lose anything by using a Z6 block - the Z6 P28 pistons have a compression height of 30mm which makes them sit at the top of the block - the A6 PM6 pistons have a compression height of 29.5mm which makes them sit "down in the hole" 0.5mm or 0.020" - a D16Z6 block with D16A6 pistons and D16Y8 head with D16A6 gasket will give you compression ratio of 10.07:1

mattie_96

hmm...that puts a good twist on what I "thought" according to the internet compression ratio calculator and all that type of info.
So then what your saying Jlicrx...is that using the a6 pistons will basically be pointless....as the z6 ones would yield a higher compression ratio?

By the way,, as far as the cam concern, Ide just be using my stock y8.
I wouldnt want to settle for the stock y8 CR which i believe is 9.6:1...ide be happy with 10.3 - 10.8:1. But ill do some more research..thanks again.

and ya i see what you mean, as effective clearance measures can only be determined when vtec is activated, but just jumping the solenoid will burn it out...so thats another one

jlicrx

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by mattie_96 &raquo;</TD></TR><TR><TD CLASS="quote">hmm...that puts a good twist on what I "thought" according to the internet compression ratio calculator and all that type of info.
So then what your saying Jlicrx...is that using the a6 pistons will basically be pointless....as the z6 ones would yield a higher compression ratio?

By the way,, as far as the cam concern, Ide just be using my stock y8.
I wouldnt want to settle for the stock y8 CR which i believe is 9.6:1...ide be happy with 10.3 - 10.8:1. But ill do some more research..thanks again.

and ya i see what you mean, as effective clearance measures can only be determined when vtec is activated, but just jumping the solenoid will burn it out...so thats another one </TD></TR></TABLE>
A6 pistons will raise the compression to 10.07:1 due to smaller dish - if you used the Z6 block, Y8 head, PM6 pistons, A6 head gasket and decked the block 0.020" so that pistons were at the top of the block, you would have compression ratio of 10.56:1 and you should still have plenty of clearance with the Y8 cam

mattie_96

ok i think thats what i will do then.
a6 pistons , the z6 block and bottom end(rods, crank etc..except for the pistons), and y8 head(stock cam)........and y8 steel head gasket

mattie_96

OK lets use some math here to "theoretically " answer my question

The Piston Deck Clearance Formula is:

Deck Height - Compression Height - Rod Length - (Stroke/2) = Piston Deck Clearance

deck height= 212mm (for z6,a6,andy8)
Compression height= 29.5mm for PM6 pistons
Rod length= 137mm(z6,a6,y8)
stroke= 90mm(z6,a6,y8)

= a piston deck clearance of 0.5mm which is 0.019685 inches...which mean the piston will be in the hole at TDC about 0.020 inches but i hope when vtec engages there wont be any interference which i understand interference really arises when u use a high performance cam with different duration which then causes headaches.

and because this is a daily driver and winter car....i wont be using the y8 headgasket...but rather the a6 head gasket or a steel equivalent will yield 10.07:1 or so of a CR...which is PERFECT for my needs