compression ratio help
 

I need some help finding my compression ratio of this setup.

b18a1 block with CP Gsr pistons compression 9.0.1 compression height 1.181 cp part number is CP7010.

integra LS eagle rods

block was decked for gasket sealing about .010 over

B16 head, shaved .040 over

head gasket stock thickness.

whats the compression ratio with this setup?

I order a cometic .051mm head gasket to be safe

Re: compression ratio help
 

specs on the piston are 29.525mm compressed height, and -4mm dome. compression w/ that combo come out to 8.60:1 or something like that w/out the block decked .010, w/ block or head shaved .010 it goes to 8.77:1

Re: compression ratio help
 

are you sure? I am under the impression that I am running 10.5.1 compression, I tried using the compression calculator but was not sure about the results. someone at h-t said 9.5.1 which is acceptable, but 8.7.1 does not sound correct. this car is even powerful in N/A form thats not possible at 8.7.1 compression

Re: compression ratio help
 

no i am not sure, all thats according to the compression calculator.

Re: compression ratio help
 

I wish I could get some more input on this I am very paranoid with it. even though I still run 21psi at the track, and 13 psi daily. every now and then 21psi in the streets.

Re: compression ratio help
 

ok well, just believe me then, i dont see how my calculations could be off, unless the compression calculator has a wrong spec somewhere. im not familiar enough w/ B series to see if the deck heights and all are correct on that particular calculator.

Re: compression ratio help
 

if I go with you I would up the boost to 35psi and boom, but it made me feel better about running 21psi without worry. thanks for the help though

Re: compression ratio help
 

comp calculator says 8.7ish
question now is how much do you trust that comp calculator

Re: compression ratio help
 

exactly, i know for sure the D series calculator has the wrong D15 deck height, no telling whats wrong w/ the B calculator. i wouldnt recommend boost level based on compression ratio though.

Re: compression ratio help
 

both D compresssion calcs SHOULD have the correct deck height now......

I know zealautoworks is correct.......

can also do it the correct why, if your good at math :)

Using the 9:1 GSR slugs in your setup, I'm guessing they have a 7cc dish......

I'm coming up 10.48:1 compression with those pistons in your motor.

.5 mm shorter deck + .050" milled are the big factors.

Re: compression ratio help
 

yeah, zealworks is the only one that is correct, but it doesnt matter, because the rest you have to figure piston to top of deck clearance manually.

i dont know many specs on the B series to check the calculator for errors, but everything seems right.

how i figured it was took stock c1 specs and adjusted the piston compressed height to that of your aftermarket piston, then adjusted the dome height to get 9.0:1, which made it -4.0 cc dome. then just swapped the block and rods to that of the LS, and came out w/ the calculations.

Re: compression ratio help
 

damn! thats strange, it seems with all the shavings thats been done to the head and the block I would be at 11.5.1 but instead its lower
so now with the new head gasket I should be at 7.0.1 or something in that range, I suck at math so thats hard

Re: compression ratio help
 

got do the cc adjustment before factoring in the compression height.

Re: compression ratio help
 

it will still work out to the same thing. specs on the piston are as i said above, cant be differant, unless CP doesnt know the correct specs. i wish manufacturers would just list the specs instead of claiimed compression ratio.

Re: compression ratio help
 

I came up with 9.0.1 I figured out the dome cc off arias pistons website, with the help of a friend

compression height= 29.9974
dome cc= -12
headgasket thickness = 0.001 thats after subtracting .040 and .010 from .051 for the head milling and decking
b18a rods
b18c pistons

http://www.zealautowerks.com/index.html

Re: compression ratio help
 

on the zealworks calculator w/ the milled block and head and the thicker gasket 9.97:1.

Re: compression ratio help
 

I look at it like this, even if we are off a little, as long as its below 10 compression I feel better.

Re: compression ratio help
 

well, as long as you use that .051 headgasket it should be.