5.0 Engine Size Calculation
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Mach 1 Member
Joined: January 18, 2010
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From: KC, MO
5.0 Engine Size Calculation
I've seen quite a few posts in various forums (primarily at other sites) where people seem confused about how engine size is calculated, especially in the case of the old 5.0 (or 4.9) vs the new 5.0. People here seem more informed than anywhere else, but I thought it would still be nice to have a new thread on the topic that tries to clear up any uncertainties.
Most of the problems come from people using already rounded numbers to convert to other units, so the most important thing to determine is which units are the base units from the factory that are not rounded.
Lets start with the equations:
b_mm = bore in mm
s_mm = stroke in mm
b_in = bore in inches
s_in = stroke in inches
cc = cubic centimeters
ci = cubic inches
L = liters
x = number of cylinders
Lets assume we know bore and stroke in both mm and inches. To calculate the rest:
Volume of cylinder = pi * radius^2 * height
ci = pi * (b_in/2)^2 * s_in * x
cc = pi * (b_mm/20)^2 * s_mm/10 * x
L = cc / 1000
And a helper conversion factor: 25.4 mm = 1 inch
Now lets consider the engines.
The old 5.0 was a 4 inch bore by 3 inch stroke. I *think* these were the unrounded exact numbers. Given this:
bore = 4 inch = 101.6 mm
stroke = 3 inch = 76.2 mm
ci = 301.5929... which correctly rounds to 302 ci
cc = 4942.222... which correctly rounds to 4.9 L (oh no! It's not a 5 oh!)
The new 5.0 I've seen listed as 92.2 mm bore by 92.8 mm stroke, but I might have seen it in inches somewhere to. Lets start with mm.
bore = 92.2 mm = 3.629921... inch
stroke = 92.8 mm = 3.653543... inch
ci = 302.4743... which correctly rounds to 302 ci
cc = 4956.666... which correctly rounds to 5.0 L
But this doesn't seem to match up exactly with some of the articles I've seen. Maybe the new 5.0 is still measured exactly in inches. Lets assume the actual unrounded factory numbers are 3.63 bore by 3.65 stroke. In this case:
bore = 3.63 inch = 92.202 mm
stroke = 3.65 inch = 92.71 mm
ci = 302.1941... which correctly rounds to 302 ci, and also rounds to 302.2 ci which I've seen in at least one article.
cc = 4952.074... which correctly rounds to 5.0 L, and I've also seen the 4952 cc in at least one article.
At this point it is fairly clear how the old 5.0 was actually a 4.9, whereas the new 5.0 can be a true 5.0, despite both being listed as 302 cubic inches (rounded of course). However, I still don't know what the true bore and stroke measurements are for the new 5.0. Anyone know?
Most of the problems come from people using already rounded numbers to convert to other units, so the most important thing to determine is which units are the base units from the factory that are not rounded.
Lets start with the equations:
b_mm = bore in mm
s_mm = stroke in mm
b_in = bore in inches
s_in = stroke in inches
cc = cubic centimeters
ci = cubic inches
L = liters
x = number of cylinders
Lets assume we know bore and stroke in both mm and inches. To calculate the rest:
Volume of cylinder = pi * radius^2 * height
ci = pi * (b_in/2)^2 * s_in * x
cc = pi * (b_mm/20)^2 * s_mm/10 * x
L = cc / 1000
And a helper conversion factor: 25.4 mm = 1 inch
Now lets consider the engines.
The old 5.0 was a 4 inch bore by 3 inch stroke. I *think* these were the unrounded exact numbers. Given this:
bore = 4 inch = 101.6 mm
stroke = 3 inch = 76.2 mm
ci = 301.5929... which correctly rounds to 302 ci
cc = 4942.222... which correctly rounds to 4.9 L (oh no! It's not a 5 oh!)
The new 5.0 I've seen listed as 92.2 mm bore by 92.8 mm stroke, but I might have seen it in inches somewhere to. Lets start with mm.
bore = 92.2 mm = 3.629921... inch
stroke = 92.8 mm = 3.653543... inch
ci = 302.4743... which correctly rounds to 302 ci
cc = 4956.666... which correctly rounds to 5.0 L
But this doesn't seem to match up exactly with some of the articles I've seen. Maybe the new 5.0 is still measured exactly in inches. Lets assume the actual unrounded factory numbers are 3.63 bore by 3.65 stroke. In this case:
bore = 3.63 inch = 92.202 mm
stroke = 3.65 inch = 92.71 mm
ci = 302.1941... which correctly rounds to 302 ci, and also rounds to 302.2 ci which I've seen in at least one article.
cc = 4952.074... which correctly rounds to 5.0 L, and I've also seen the 4952 cc in at least one article.
At this point it is fairly clear how the old 5.0 was actually a 4.9, whereas the new 5.0 can be a true 5.0, despite both being listed as 302 cubic inches (rounded of course). However, I still don't know what the true bore and stroke measurements are for the new 5.0. Anyone know?
Last edited by Skotty; Feb 5, 2010 at 10:10 AM. Reason: Changed cubic inches abbrev. from cu to ci / changed "Area" to "Volume"
Jesus. Who cares 
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Joined: October 9, 2007
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I don't know the bore and stroke either, but I did also see the 4952cc number and ran it backwards just to see how much difference it made in the old 302 number.
No doubt someone decided that this thing better round up to 5000cc so that Ford wouldn't have to hear it's really a 4.9L in all the trades.
No doubt someone decided that this thing better round up to 5000cc so that Ford wouldn't have to hear it's really a 4.9L in all the trades.
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Joined: December 14, 2007
Posts: 19,953
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From: State of Jefferson Mountains USA
The March 5.0 article says 92.2 x 92.8mm or 3.263 x 3.647in for 4957cc or 302ci:
http://s42.photobucket.com/albums/e3...t=scan0020.jpg
Do your math thing and report back
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