i got these pistons and trying to find the compression ratio for them they are as follows

189681 81mm std. 3.433 5.429 1.181 41.5 9:1 -9.3 280 $595.00 Order Now

it says they are 9:1 but that is for the GSR they are now in a B16A block does that mean the compression ratio will drop drasticly? or moderitly?

 

could you please clear up the question. do have
1. GSR block with B16 head
2. B16 block with GSR head
3. LS block wirh GSR head
4. LS block with B16 head
5. straight B16
6. striaght GSR

 

b16a block with gsr head

 

your comp ratio is gonna be around the 9.4:1 area if you want the formula or some help to it PM i can get ya straight

 

7.97:1 according to the Zeal calculator.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by NJIN BUILDR &raquo;</TD></TR><TR><TD CLASS="quote">7.97:1 according to the Zeal calculator.</TD></TR></TABLE>

i dont agree with that if he only changed the head point me in the direction of the zeal calc. here is the formulas i use

comp ratio= cylinder + chamber volume / chamber volume

 

i think the only thing that is different between the b18c1 and b16a is the stroke, everythnig else is pretty much the same i believe.

how could it go from 9:1 to 7:x:1 thats a huge jump down

 

http://www.zealautowerks.com/

The 9:1 is for a 1.8L,he has a 1.6L.

 

i get 8:26:1 with a 1 layer headgasket, it looks like i would need to get the thinnest **** ever lol

 

The piston would hit the head with a one layer and a gsr head.You need to have the head milled if you need 9:1.

 

njin i believe we got it here try what i use
1. cylinder volume= pi / (4)(bore^2)(stroke)
2. comp ratio= cylinder + chamber volume / chamber volume

 

how much would it have to be milled to be 9:1

 

to figure out mill here ya go

new disp. ratio - old disp. ratio
------------------------------------ (stroke)
(new disp. ratio) (old disp. ratio)


EDIT: this will tell how many inches to mill off to get mm multiply inches by 25.4

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by tony413 &raquo;</TD></TR><TR><TD CLASS="quote">njin i believe we got it here try what i use
1. cylinder volume= pi / (4)(bore^2)(stroke)
2. comp ratio= cylinder + chamber volume / chamber volume
</TD></TR></TABLE>

Your going to make me do it the long way.OK here we go.

1. pi x r2 = 3.1416 x (1.5945 x 1.5945) x 3.047 x 16.387 = 398.81 cc

2. 398.81 + 41.6 + 9.3 + 3.4 = 453.11 / 54.3 = 8.34:1

The zeal calculator uses some different volumes for the gasket and squish.These calculators are good for quick estimates of component changes.

 

do you think thats stupid low

ill be running a gt3582r on it

 

so is the real calculation 8:3?:1

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by NJIN BUILDR &raquo;</TD></TR><TR><TD CLASS="quote">

Your going to make me do it the long way.OK here we go.

1. pi x r2 = 3.1416 x (1.5945 x 1.5945) x 3.047 x 16.387 = 398.81 cc

2. 398.81 + 41.6 + 9.3 + 3.4 = 453.11 / 54.3 = 8.34:1

The zeal calculator uses some different volumes for the gasket and squish.These calculators are good for quick estimates of component changes.</TD></TR></TABLE>

hahahaha j/k kiding but i knew 7.97 was way to low now with what you just solved we can also figure out the comp ratio with different gaskets and if we need to mill anything which i posted.

to the OP running that comp ratio with a GT35 should be no problem if you wanna boost alot do it if you dont its cool also you gotta remember the CC chambers on the B16 head(42.7) are than on the GSR head(41.6) and that Affect comp ratio alot

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by b18sihatch &raquo;</TD></TR><TR><TD CLASS="quote">how much would it have to be milled to be 9:1</TD></TR></TABLE>

The better option is to get part #176449. That will give you about 9.5 without milling.And using a cometic .043" gasket with this piston will give you about 9.2:1.

 

Modified by NJIN BUILDR at 7:30 AM 4/17/2007

 

the motor is already built so i dont have the luxury of changing my mind now lol.

so is the static pressure 8:34:1 without a thinner headgasket?

 

you are correct but changing a head gasket is $80 and about an hours worth of ime depending on how good you wrench

 

well the block is sitting in my room lol, so headgasket is easy lol

say i go with a 2 layer gasket what would that bring the compression to?

i cant figure this stuff out for **** becuase i am VERY much not good with math lol and its way above me hence why icouldnt work those zeal calculator that and like the other poster said its a rough esimate a solid answer is always better than guessing lol

 

c/r=(volume of cylinder at bdc)/(volume of cylinder at tdc)
But that's pretty much impossible to determine w/o cc'ing the engine...so i'll find a link to the comp. calc. i always use.

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

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by CivicVX94 &raquo;</TD></TR><TR><TD CLASS="quote">c/r=(volume of cylinder at bdc)/(volume of cylinder at tdc)
But that's pretty much impossible to determine w/o cc'ing the engine...so i'll find a link to the comp. calc. i always use.</TD></TR></TABLE>

take a pipet a clear piece of plastic to block the heads cambustion(sp) chamber and from there slowly start adding water with the pipet. once the chamber is fill you measure the amount of water you dropped in there an boom thats the CC of the heads cambers if you want to do the block same procress applies just a different way

 

so is or isnt the 8:34:1 roughly the correct eastimate of the Compression ratio?
the block is:

sleeved
81mm
JE pistons
Crower h beam rods

looking to push 20-28psi with it, not sure how the compression will make the boost respond however he motor was really ever geared towards full on track racing, more so of a ''highway'' racer it also has the longer ls geared transmision with LSD so highway the gearing is much better for