|
Sponsored Links (Register now to hide all advertisements) |
|
|
Thread Tools | Display Modes |
|
11-17-2020, 04:56 PM | #1 |
Senior Member
Join Date: May 2010
Location: Lakewood, CO
Posts: 413
|
Cubic inch question
I have a Ford 8ba that has been bored .040 over and has a Merc. crank. What cubic inch does this come out to? Thank you and sorry for my ignorance.
|
11-17-2020, 05:16 PM | #2 |
Senior Member
Join Date: Dec 2013
Location: Minnesota, Florida Keys
Posts: 10,321
|
Re: Cubic inch question
261.8 (let's call it a 262).
|
Sponsored Links (Register now to hide all advertisements) |
|
11-17-2020, 05:30 PM | #3 |
Senior Member
Join Date: May 2010
Location: East Shore of LAKE HOUSTON
Posts: 11,115
|
Re: Cubic inch question
That tubman sure knows how to punch a calculator....on the money! DD
|
11-17-2020, 06:52 PM | #4 |
Senior Member
Join Date: Dec 2013
Location: Minnesota, Florida Keys
Posts: 10,321
|
Re: Cubic inch question
Yeah, but I didn't have to look up the mathematical formula required. When I was in college taking physics, calculating devices (slide rules in my day) were OK during tests. They were checking your knowledge of Physics, not your math abilities.
Last edited by tubman; 11-17-2020 at 09:19 PM. |
11-17-2020, 07:27 PM | #5 |
Senior Member
Join Date: May 2010
Location: East Shore of LAKE HOUSTON
Posts: 11,115
|
Re: Cubic inch question
I've known that formula (by heart) since junior high. And I do it the ".7854" way. DD
|
11-17-2020, 08:21 PM | #6 |
Senior Member
Join Date: May 2010
Posts: 267
|
Re: Cubic inch question
Sponsored Links (Register now to hide all advertisements)
|
11-18-2020, 01:35 AM | #7 | |
Senior Member
Join Date: May 2010
Location: East Shore of LAKE HOUSTON
Posts: 11,115
|
Re: Cubic inch question
Quote:
OK, "0.7854" is a function of pi, accurate to at least four decimal places. 0.7854 = 3.1416/4 or (3.1416 divided by 4). Example: Bore X Bore X Stroke X .7854 X 8 (cyls.) = Cu. In. Your FIRST Example: Bore = 3.1875 + 0.040 = 3.2275 Stroke = 4.0 Constant = .7854 Number of Cylinders = 8 __________________________________ So: 3.2275 X 3.2275 X 4 X 0.7854 X 8 = 261.80224 |
|
11-17-2020, 08:32 PM | #8 |
Senior Member
Join Date: May 2017
Location: Arkansas
Posts: 611
|
Re: Cubic inch question
So is my .080 over gonna be 269?
|
11-17-2020, 09:16 PM | #9 |
Senior Member
Join Date: Apr 2019
Location: Kansas
Posts: 926
|
Re: Cubic inch question
268.33
(pi X bore radius squared x stroke x 8)
__________________
"It don't take but country smarts to solve the problem" (Smokey Yunick) '41 Merc Town Sedan / 260" 8CM engine '66 Fairlane four door / "warmed up" 302 |
11-17-2020, 09:38 PM | #10 |
Senior Member
Join Date: May 2017
Location: Arkansas
Posts: 611
|
Re: Cubic inch question
Thanks cad, guess I better say 268.
|
11-17-2020, 10:13 PM | #11 |
Senior Member
Join Date: May 2010
Location: Lakewood, CO
Posts: 413
|
Re: Cubic inch question
Thanks, that's what I came up with but was told it was wrong.
|
11-18-2020, 02:00 AM | #12 |
Senior Member
Join Date: Jul 2019
Location: Southern Oregon
Posts: 782
|
Re: Cubic inch question
I do it slightly different.
I punch in the bore (3.2275), then I hit the squared button (² ), after that, I multiple by .7854, then times stroke (4) and finally, times 8 = 261.80225148 Darn, I got a different answer, what happened One of the nice things about using .7854, is that on number pads, it is the top, left hand corner keys. Makes it a little easier for me.
__________________
Frank '35 Ford Model 51 '48 Ford F3 '54 Ford Tudor Mainline |
11-18-2020, 03:04 AM | #13 |
Senior Member
Join Date: May 2017
Location: Arkansas
Posts: 611
|
Re: Cubic inch question
It would take me 10 years to understand why you square the bore measurement.
|
11-18-2020, 03:38 AM | #14 |
Senior Member
Join Date: May 2010
Location: Solihull, England.
Posts: 8,756
|
Re: Cubic inch question
You square it because you want the area of the cylinder.
Area of a circle is Pi r squared. Because we know the bore rather than the radius, we have to use the alternative formula that uses the diameter. Area of a circle is pi d squared all over 4. (over = divided by) Volume of one cylinder of a stock 239 for example is: 3.1875 * 3.1875 * 3.1416 / 4 Which equals 7.9798. Unit is square inches. Volume of a cylinder = area * length. So 7.9798 * 3.75 = 29.9242. Now the unit is cubic inches. So just shy of 30 cu in. Volume of the engine is volume of one cylinder times the number of cylinders. So 29.9242 * 8 = 239.3936 Rounded to 239 for ease of reference. I used a known engine because we are already familiar with the answer. In the examples above the shortcut is to use pi/4. 3.1416/4 = .7854. The above formulae are completely universal and by using centimeters the volume in cc can be calculated. Mart. |
11-18-2020, 04:29 PM | #15 |
Senior Member
Join Date: May 2010
Posts: 267
|
Re: Cubic inch question
thanks, fellas. Terry
|
11-18-2020, 05:20 PM | #16 |
Senior Member
Join Date: Jul 2011
Location: SF Bay Area
Posts: 6,648
|
Re: Cubic inch question
In my dotage now, my sliderule days are long forgotten, but you can do more today with a $6.99 drugstore calculator than the best sliderule ever made.
My old sliderule was never much good for making straight lines anyway, with that bumpy thingy right there in the middle. I will say though, I had a round one once that helped me earn free pizza in my sports car rally days. (Back in the day, you'd have to tell them if you didn't want anchovies.) Come to think of it, I guess I could have used my sliderule to determine how much beer was in a "'Yard of Beer' Stein".
__________________
Alan |
11-18-2020, 05:25 PM | #17 |
Senior Member
Join Date: May 2010
Location: southeastern Michigan
Posts: 10,104
|
Re: Cubic inch question
Mart,
With respect, if we know the bore diameter, we automatically know the radius as it is one half of the diameter. |
11-18-2020, 05:33 PM | #18 |
Senior Member
Join Date: Jun 2014
Location: New Jersey
Posts: 1,772
|
Re: Cubic inch question
Who says one only remembers 5 minutes of what they learned in 5 years of college?
You guys have proved them wrong
__________________
Thanks Andy 1952 F1 |
11-18-2020, 05:52 PM | #19 | |
Senior Member
Join Date: Jul 2011
Location: SF Bay Area
Posts: 6,648
|
Re: Cubic inch question
Quote:
Aw, I retain very fond memories of a few 5 minute sessions in college!
__________________
Alan |
|
11-18-2020, 06:05 PM | #20 |
Senior Member
Join Date: May 2010
Posts: 1,648
|
Re: Cubic inch question
|
|
|
Sponsored Links (Register now to hide all advertisements) |
|