compression ratio help
#1
compression ratio help
I have a 2004 5.3 which has a 7cc factory dished piston
trying to decide how much to mill my 243 heads to achieve a 10.0 to 1 static comp ratio
243 heads have a 64.45 cc chamber and it takes .007 to remove 1 cc
milled .042 achieves 58.45cc chamber which i came up with 10.09 to 1 comp
milled .049 achieves 57.45cc chamber which i came up with 10.2 to 1comp
Can someone double check my numbers for me?
These are the numbers i put in the comp calculator
3.779 bore
3.662 stroke
-7cc piston dish
.053 head gasket thickness
3.903 head gasket bore
.010 piston out of the hole
9.240 deck height
trying to decide how much to mill my 243 heads to achieve a 10.0 to 1 static comp ratio
243 heads have a 64.45 cc chamber and it takes .007 to remove 1 cc
milled .042 achieves 58.45cc chamber which i came up with 10.09 to 1 comp
milled .049 achieves 57.45cc chamber which i came up with 10.2 to 1comp
Can someone double check my numbers for me?
These are the numbers i put in the comp calculator
3.779 bore
3.662 stroke
-7cc piston dish
.053 head gasket thickness
3.903 head gasket bore
.010 piston out of the hole
9.240 deck height
#2
I have a gauge for that
iTrader: (42)
Welllllll the easier way than guessing is to just plug it directly into the calculator, Engine Compression Ratio (CR) Calculator
Put in all the stuff then at the bottom put in 10:1 for the CR then click calc combustion chamber volume.
According to that you need a 55.034cc chamber for 10:1 SCR. So with your 0.007in per cc, thats (64.45-55.034)*0.007=0.0659in mill.
With that said, the stock deck is only about .375" thick, so you are going to cut off about 18% of the deck to get the higher compression. This is not a good idea if you plan on lots of boost or nitrous. Also, you need to be meticulous about checking PTV clearance. 0.0659 is a huge mill. I wouldnt do it.
Put in all the stuff then at the bottom put in 10:1 for the CR then click calc combustion chamber volume.
According to that you need a 55.034cc chamber for 10:1 SCR. So with your 0.007in per cc, thats (64.45-55.034)*0.007=0.0659in mill.
With that said, the stock deck is only about .375" thick, so you are going to cut off about 18% of the deck to get the higher compression. This is not a good idea if you plan on lots of boost or nitrous. Also, you need to be meticulous about checking PTV clearance. 0.0659 is a huge mill. I wouldnt do it.
#3
ok i figured it out!....Thanks for the help ATOMIC
SO STOCK 243 HEADS ON A 5.3 99-06 with factory dish piston
57.25cc chamber is 9.8 to 1 milled .050
58.13cc chamber is 9.7 to 1 milled .044
59.03cc chamber is 9.6 to 1 milled .038
59.95cc chamber is 9.5 to 1 milled .031
I was expecting to gain more compression than that!
SO STOCK 243 HEADS ON A 5.3 99-06 with factory dish piston
57.25cc chamber is 9.8 to 1 milled .050
58.13cc chamber is 9.7 to 1 milled .044
59.03cc chamber is 9.6 to 1 milled .038
59.95cc chamber is 9.5 to 1 milled .031
I was expecting to gain more compression than that!
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