Compression ratio?
- Thread starter SMOKEDYA
- Start date
RSR Static Compression Ratio Calculator
if you camshaft has overlap it will also bleed off some compression.
if you camshaft has overlap it will also bleed off some compression.
John,
If you want to drive up to Arlington, we can measure the dish and diameter of the top ring land. I don't remember where you were located...
I have an excel spreadsheet at home that will make the number crunching a ton easier, and it accounts for the volume above the top ring...
I didn't bother with dynamic compression though...
jason
If you want to drive up to Arlington, we can measure the dish and diameter of the top ring land. I don't remember where you were located...
I have an excel spreadsheet at home that will make the number crunching a ton easier, and it accounts for the volume above the top ring...
I didn't bother with dynamic compression though...
jason
The main ingredients of a static compression ratio are very simple:
- Cylinder swept volume = Bore(2)*stroke*.7854
- Clearance volume = .7854*(piston top from engine deck height)*Bore(2)
- Piston dome(+), dish(-), or flat (0) = cubic centimeters
- Head-gasket volume (gasket height*.7854*Bore(2)
- Cylinder head chamber volume = cubic centimeters
The ring land volume creates a very minimal change by accounting for the piston to wall distance and the distance from the top ring to the top of the piston volume.
Atleast it is easier to quantify better than blow-by and other variables that change at every degree of crank rotation.
FYI, .7854 is a rounded off number for PI/4. Relatively speaking, it is the area of a circle inside a square.
- Cylinder swept volume = Bore(2)*stroke*.7854
- Clearance volume = .7854*(piston top from engine deck height)*Bore(2)
- Piston dome(+), dish(-), or flat (0) = cubic centimeters
- Head-gasket volume (gasket height*.7854*Bore(2)
- Cylinder head chamber volume = cubic centimeters
The ring land volume creates a very minimal change by accounting for the piston to wall distance and the distance from the top ring to the top of the piston volume.
Atleast it is easier to quantify better than blow-by and other variables that change at every degree of crank rotation.
FYI, .7854 is a rounded off number for PI/4. Relatively speaking, it is the area of a circle inside a square.
No i do not know the part number of the pistons,and i know i shoulda looked when i put the motor together.Isnt the part number on the inside backside of the pistons where the rods connect? All there was was a 0.40 stamped in the dish of the pistons so i assumed they are 40 over? But yes this is what i'm trying to figure out the CC of the pistons. My heads are 58CC and i have 1011-1 head gaskets. jason wouldnt i need the motor out of the car to do this? I live in vancouver but i dont mind the drive i took it to HP ranch for my tune
. peacejohn
Yeah, I thought you had stuff apart...jason wouldnt i need the motor out of the car to do this? I live in vancouver but i dont mind the drive i took it to HP ranch for my tune
john
Do you remember who you purchased the pistons from?
They may still have a record/invoice of what you picked up
I suppose you could cc the piston by pulling the head....
Gets trickier if the piston doesn't stick out of the hole though
I dont have any build specs of the block,just the cam card. I bought the motor complete from a guy here who got it from another guy. All i did was pull all the bearing and inspect them to make sure they were good before i put money into the motor. They looked excellent but like i said i never thought of looking for a part number on the pistons tho.The pistons dont stick up over the cylinders peace
john
john
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