rebuilding the 'ol z6 and can't decide if i want to go a6 pistons (about 10.6:1cr) or y8's (about 10:1 cr) - the cars a daily driver and will be putting a lot of "normal driver" miles on it - but it will be autox'd as well. . .

 

up

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by FriedEnt &raquo;</TD></TR><TR><TD CLASS="quote">rebuilding the 'ol z6 and can't decide if i want to go a6 pistons (about 10.6:1cr) or y8's (about 10:1 cr) - the cars a daily driver and will be putting a lot of "normal driver" miles on it - but it will be autox'd as well. . . </TD></TR></TABLE>

That puts a spin on it. Are you going to X it alot, do you want to be competitive, does it even matter what class you're in?

Either way, I don't see why you'd want to drop your CR.

 

I myself am going with the PM6(d16a6) pistons for the higher compression

 

I was using the D series compression calculator and it was showing an increase in compression - I may haved made a mistake

I was going to go a6 pistons too - but was looking for something that needed a little less tuning to be able to drive it regularly

I am mainly autox'ing for fun - competition and classes don't matter much to me right now

 

Nope, just ran the comp calculator too, and choosing everything z6, then just swapping to y8 pistons you go from 9.13 CR to 9.84 CR.

http://www.knology.net/%7Ejediklc/D.htm

 

unfortunately though you forgot to take into account the compression height of the pistons...

P2P pistons (d16y8) yield 9.4:1 in a z6 block because their compression height is 29.50mm which is the same as the PM6 (D16a6) which would yield 9.95:1

The stock z6 piston's compression height is 30mm

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by FriedEnt &raquo;</TD></TR><TR><TD CLASS="quote"> competition and classes don't matter much to me right now </TD></TR></TABLE>

Then I'd go with the highest compression pistons. You won't need to tune, but you might have to step up to 89 octane to prevent detonation.

 

No tuning? A buddy of mine (races autox nationally and builds motors http://www.crxmotorsports.com) told me to step up to a6 pistons but afterwords I would need to have the car dynotuned. I don't have the money to dyno tune, so that sort of geared me away from high compression. . . I just want to bump the pep up alittle and not risk any thing. . .

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by TuningOptions &raquo;</TD></TR><TR><TD CLASS="quote">No tuning? A buddy of mine (races autox nationally and builds motors http://www.crxmotorsports.com) told me to step up to a6 pistons but afterwords I would need to have the car dynotuned. I don't have the money to dyno tune, so that sort of geared me away from high compression. . . I just want to bump the pep up alittle and not risk any thing. . . </TD></TR></TABLE>

To get the most out of it, it should be tuned. But basically you're just bumping the CR on a stock motor, so up the octane to prevent detonation. You won't be getting the full potential of the motor, but you'll be running safe.

 

I see - Thanks - so I should go ahead with the A6's or are there better pistons. . . ?

 

I mean if you want to go buckwild High compression, go with some ZC pistons...I'm rebuilding a d16z6 w/ the block punched out 20 over and oversized pm6 pistons...so I'll let you know how it all turns out.