Alright, i have some CP pistons i'm putting in my B16. The pistons are for a B18 and are 9:1 compression ratio. The guy i bought them from said it would be different for the b16 since the compression ration is for the b18. How would i figure out what my compression ratio is?

 

http://www.c-speedracing.com/h...c.php

 

Thanks for the link, but I have another problem...i don't know the dome displacement for the piston i'm using. Its a CP piston, 83mm and is for a b18. For the b18 it should be 9:1

 

did the head change, or the stroke?

 

no, still the B16 head and the stock stroke.

 

if you're not changing the head or the stroke the pistons are designed for, you're not gonna be changing the compression ratio. (cept for with the head gasket, but that's minmal)

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by xyrth &raquo;</TD></TR><TR><TD CLASS="quote">if you're not changing the head or the stroke the pistons are designed for, you're not gonna be changing the compression ratio. (cept for with the head gasket, but that's minmal)</TD></TR></TABLE>

right, but he's saying the pistons were made with a b18X combustion chamber in mind....not the b16 head he is using. He is curious what the compression would be taking that into account.

you could just go to a comp calc and put the b16 combustion chamber CC in place of the b18X and see what the difference is vs. when you put the b18X volume in...then take that difference and assume that point difference would apply to your situation.

for instance, on SOHC, a d16y8 head will yield approx. .5 pts higher compression than a d1z6 head

To be honest, i would call the manufacturer to get the different measurements and input them into a comp calc...or ****, even as CP to do it for you (calculate)

 

I emailed CP and they said it was -10.2cc dome volume

 

Well with that dome volume it came out to 8:1 CR. That is way to low of course. I contacted the company I bought it from and am getting another set shipped to me that will come out to be 8.5:1, i'm still thinking this to low so I was considering milling the head to get it up to about 8.8:1, but some are telling me I should still go higher for my application. I'm not really sure what to do.

 

turbo/naws/na?

i'd say go at least 9:1 ... i dun really like milling heads just for compression, cause you can get to the end of the life for the head to quick, replacing a head when you blow a HG is just too pricey.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by xyrth &raquo;</TD></TR><TR><TD CLASS="quote"> i dun really like milling heads just for compression, cause you can get to the end of the life for the head to quick, replacing a head when you blow a HG is just too pricey.</TD></TR></TABLE>

this is how i feel too....

 

turbo and NOS, I have Darton sleeves, crower rods and an eagle crank so its a strong block

 

what kind of fuel? i'd go atleast 9:1.

 

i'd like to use pump gas 93 octane and then turn the boost up on the track with race fuel. what piston would be a 9:1? i can't find one, all are less or more

 

i guess you are looking for shelved pistons? i thought Wiseco had a shelved 9:1 piston for b16? might not be 9:1...maybe right under that.

What bore are the sleeves?

at any rate, Mahle, JE, Wiseco, etc can make them per your application, they just will be slightly higher than the shelved ones.

 

right now the sleeves are the stock bore, but I want to bore them out to 83 or 84mm. I did find a 83mm bored arias piston that is 9.3:1.