Displacement is how much volume is compressed./QUOTE]
Displacement is bore times stroke. Also known as "Swept Volume". For multi cylinder engines, it is also times the number of cylinders for total displacement. But, each cylinder/head unit is nominally equal, so it is easier to only talk about a single cylinder. The volume compressed is displacement plus cylinder head volume plus any cylinder volume above the piston at TDC plus head gasket thickness times bore. I am leaving out piston dome or relief to make things simpler.
???? No idea what you are trying to say.C/R relates to the total volume after displacement / compression.
Yep, this.Some of the total cyl volume is not displaced. C/R is a ratio of total volume relative to displaced volume.
Good explanation here. https://www.youtube.com/watch?v=8Q83erQRAcU
........ Can only say that the surface presented to the cylinder is effectively 3.75 in^3 taller from the wrist pin.
I think you meant to say ‘3.75 DIVIDED BY the cross sectional area of the cylinder taller...’
If instead, the OP is looking for clearance volume, the volume above the piston at TDC, the arithmetic is easy. ( Aero Mechanics High School, 1952)
Its Displacement / (CR-1).
So, for an O-360 lyc, 90 cu in / cylinder, CR = 8.5, the clearance volume of each jug would be :
90 / 7.5 = 12 cu in per cylinder.
Ron
Can't you just do something like this.
8 to 1
(90÷7)8=102.86(beginning cylinder volume)
9 to 1
(90÷8)9=101.25(beginning cylinder volume)
Not sure just curious.
Brandon
Way too many engineers on this thread. Anybody wanna help me make a cake?
I am going to assume the OPs question is actually different than stated. Swept volumes have already been answered. It is possible to calculate the starting and ending volumes with the CR and the swept volume. The relative piston volumes are then trivial.
Assuming my physics molecule still works...
Compression ratio (CR) = Starting volume/ending volume
Lets call the compressed ending volume = X
The starting volume will be = Swept volume + X
Lets calculate the ending volume on a 4 cyl 360 @ 7:1
7= (360+X)/X
7X=360+X
6X=360
X=60
Divide by 4 cylinders to get 15 in^3 per cylinder.
8.5 CR gives 12 in^3 per cylinder
9 CR gives 11.25 in^3 per cylinder
The differences in these values is how much volume difference is created by the different pistons. Without knowing the detail piston design, one cannot simply say the 9 CR piston is 3.75 in^3 of aluminum heavier than the 7 CR. Can only say that the surface presented to the cylinder is effectively 3.75 in^3 taller from the wrist pin.
I have to ask...
Do you use a liquid measuring cup to portion your dry ingredients?...
Maybe, but why is an ounce of GOLD have more mass (heavier on earth) than an ounce of LEAD?
The answer to this is buoyancy. The denser material is smaller for the same mass, so it displaces less air, so there is less buoyant force, so it will weigh out heavier on earth.
The answer to this is buoyancy. The denser material is smaller for the same mass, so it displaces less air, so there is less buoyant force, so it will weigh out heavier on earth.
True. But a much larger effect is that gold is nearly always measured in ‘Troy Ounces’ (12 to a pound) while nearly everything else is measured in traditional ounces (16 to a pound).
Just love the English measurement system.
OK,
troy ounce = 31.1034768 grams
av. ounce = 28.3494 gram
pound = 453.592 grams