Difference of Displacement
#1
Difference of Displacement
Hey guys I got this off a ford truck forum and found it interesting because of the fact that the formula works on everything but a 4.6(281CID)
{"Formula to Calculate the CID (Cubic Inch Displacement) of an engine
R² × Pi × H × number of cylinders = CID (Cubic Inch Displacement)
In other words;
Radius of the bore squared × 3.14 × Stroke × number of cylinders = CID
For Example:
If we have a V8 engine with a 4" bore and a 3" stroke, the formula would read: 2² × 3.14 × 3" × 8 = 301.44 CID
In other words;
2² (The radius of a 4" bore [2"] squared [multiplied by itself, or 2 × 2] × 3.14 (Pi = 3.1416) × 3 (3" stroke) × 8 (The number of cylinders in this engine) = 301.44 CID
This engine, by the way, is the Ford 302! This formula will work with any engine.
For example, the Oldsmobile 350 V8, which has a bore of 4.057" and a stroke of 3.385" would be; 2.0285² × 3.14 × 3.385 x 8 = 349.88742333922 CID
A Ford 351 with a bore of 4" and a stroke of 3.5" would be; 2² × 3.14 × 3.5 × 8 = 351.68 CID"}
Now as for my math this is what I get for a 4.6 (281)
bore is 3.55 and stroke is 3.54
315.68 CID
The formula that states bore x bore x 0.7854 x stroke X #cylinders = 280.31 for our 4.6. It works also for every other engine and gives the same sum as the formula shown on the truck forum. So why the difference in displacement for the 4.6 then? You do the math. You will see what I'm talking about.
{"Formula to Calculate the CID (Cubic Inch Displacement) of an engine
R² × Pi × H × number of cylinders = CID (Cubic Inch Displacement)
In other words;
Radius of the bore squared × 3.14 × Stroke × number of cylinders = CID
For Example:
If we have a V8 engine with a 4" bore and a 3" stroke, the formula would read: 2² × 3.14 × 3" × 8 = 301.44 CID
In other words;
2² (The radius of a 4" bore [2"] squared [multiplied by itself, or 2 × 2] × 3.14 (Pi = 3.1416) × 3 (3" stroke) × 8 (The number of cylinders in this engine) = 301.44 CID
This engine, by the way, is the Ford 302! This formula will work with any engine.
For example, the Oldsmobile 350 V8, which has a bore of 4.057" and a stroke of 3.385" would be; 2.0285² × 3.14 × 3.385 x 8 = 349.88742333922 CID
A Ford 351 with a bore of 4" and a stroke of 3.5" would be; 2² × 3.14 × 3.5 × 8 = 351.68 CID"}
Now as for my math this is what I get for a 4.6 (281)
bore is 3.55 and stroke is 3.54
315.68 CID
The formula that states bore x bore x 0.7854 x stroke X #cylinders = 280.31 for our 4.6. It works also for every other engine and gives the same sum as the formula shown on the truck forum. So why the difference in displacement for the 4.6 then? You do the math. You will see what I'm talking about.
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01-01-2013 08:38 PM