You affect displacement with Bore, Stroke and Number of Cylinders.
Bore is affected by the size of the piston, and Stroke is affected by the radius of the crankshaft, and well, I’m sure you understand the number of cylinders.
Contrary to popular belief changing the length of the rod, or height of the deck, does not affect any of these three, bore, stroke or cylinder count. All the rod does is connect one, (piston) to the other(crank), that is it.
The equation is:
Total Engine Displacement (cc) = (.0031416 / 4) x Bore x Bore x Stroke (mm) x Number of Cylinders
The measurement used on bore and stroke is millimeters (mm)
1JZ
Bore = 86 mm
Stroke = 71.5 mm
(.0031416 / 4) * 86 *86 * 71.5 * 6 = 2491.98 cc
2JZ
Bore = 86 mm
Stroke = 86 mm
(.0031416 / 4) * 86 *86 * 86 * 6 = 2997.35 cc
7M
Bore = 83 mm
Stroke = 91 mm
(.0031416 / 4) * 83 *83 * 91 * 6 = 2954.19 cc
Now there has been much debate on what exactly changes the displacement between the 2JZ(3.0 liters) and the 1JZ(2.5 liters) some believe it’s the rods and that the cranks are identical, the equation proves this is not possible.
Since Bore is the same (2JZ=86, 1JZ=86) this indicates that the circumference of each piston is identical, and cannot change the displacement. The number of pistons for each is 6 so this cannot change the displacement. This leaves ONLY stroke, And as was discussed earlier the ONLY thing that can affect stroke is radius of the crankshaft. This is a physical constant. It will never change over time by math or magic, science or sorcery. Because the stroke is different the crankshafts MUST therefore be different. This is a mathematical absolute, so ordered by the laws of physics. And they are different, 7.25mm different to be exact. The 2JZ crankshaft is 7.25mm longer, from main bearing journal centerline to crank throw centerline, than the 1JZ crankshaft. They may be identical in the crank throw degreeing and counterweight placement, but they are different in the radius.
This is an absolute FACT, mathematically proven and sound. The cranks are different.(period)
P.S. IJ reminded me in an earlier thread about listing the number of cylinders also changing displacement, I had forgoten to list it with the things that cahnge displacement but it was still in the equation. I had spaced it out in my earlier post because it was so obvious that I over looked it, so thanks IJ.
Bore is affected by the size of the piston, and Stroke is affected by the radius of the crankshaft, and well, I’m sure you understand the number of cylinders.
Contrary to popular belief changing the length of the rod, or height of the deck, does not affect any of these three, bore, stroke or cylinder count. All the rod does is connect one, (piston) to the other(crank), that is it.
The equation is:
Total Engine Displacement (cc) = (.0031416 / 4) x Bore x Bore x Stroke (mm) x Number of Cylinders
The measurement used on bore and stroke is millimeters (mm)
1JZ
Bore = 86 mm
Stroke = 71.5 mm
(.0031416 / 4) * 86 *86 * 71.5 * 6 = 2491.98 cc
2JZ
Bore = 86 mm
Stroke = 86 mm
(.0031416 / 4) * 86 *86 * 86 * 6 = 2997.35 cc
7M
Bore = 83 mm
Stroke = 91 mm
(.0031416 / 4) * 83 *83 * 91 * 6 = 2954.19 cc
Now there has been much debate on what exactly changes the displacement between the 2JZ(3.0 liters) and the 1JZ(2.5 liters) some believe it’s the rods and that the cranks are identical, the equation proves this is not possible.
Since Bore is the same (2JZ=86, 1JZ=86) this indicates that the circumference of each piston is identical, and cannot change the displacement. The number of pistons for each is 6 so this cannot change the displacement. This leaves ONLY stroke, And as was discussed earlier the ONLY thing that can affect stroke is radius of the crankshaft. This is a physical constant. It will never change over time by math or magic, science or sorcery. Because the stroke is different the crankshafts MUST therefore be different. This is a mathematical absolute, so ordered by the laws of physics. And they are different, 7.25mm different to be exact. The 2JZ crankshaft is 7.25mm longer, from main bearing journal centerline to crank throw centerline, than the 1JZ crankshaft. They may be identical in the crank throw degreeing and counterweight placement, but they are different in the radius.
This is an absolute FACT, mathematically proven and sound. The cranks are different.(period)
P.S. IJ reminded me in an earlier thread about listing the number of cylinders also changing displacement, I had forgoten to list it with the things that cahnge displacement but it was still in the equation. I had spaced it out in my earlier post because it was so obvious that I over looked it, so thanks IJ.
