equation for displacement?
6 & 8 Second Club
Joined: Aug 2006
Posts: 2,284
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From: Illinois, RT 66 dragway area
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How about we are not trying to make life complicated on the non 140 IQ people or showing off that we are 140+ IQ. I personally was just helping answer a simple ??
We are not trying to avoid anything. The standard formula that has been used for the 30+ years I've been doing this, is the standard formula that is close enough for 99% of people. I just did a bunch of basic sizes and every one was the same to the hundredth. If the original poster wanted it exact to the ten thousandth, than I apologize for confusing anyone. I will watch which forum I'm in closer next time.
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How about we are not trying to make life complicated on the non 140 IQ people or showing off that we are 140+ IQ. I personally was just helping answer a simple ??
We are not trying to avoid anything. The standard formula that has been used for the 30+ years I've been doing this, is the standard formula that is close enough for 99% of people. I just did a bunch of basic sizes and every one was the same to the hundredth. If the original poster wanted it exact to the ten thousandth, than I apologize for confusing anyone. I will watch which forum I'm in closer next time.
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TECH Resident
Joined: Oct 2005
Posts: 787
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Maybe I should have been using this for all these years:
http://zenwerx.com/pi.php
Sorry in advance if humor doesn't have a place in this forum. My old Commodore64 would still be chewing on this to calculate displacement.
So what's "close enough"?
http://zenwerx.com/pi.php
Sorry in advance if humor doesn't have a place in this forum. My old Commodore64 would still be chewing on this to calculate displacement.
So what's "close enough"?
Originally Posted by mrdragster1970
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How about we are not trying to make life complicated on the non 140 IQ people or showing off that we are 140+ IQ. I personally was just helping answer a simple ??
We are not trying to avoid anything. The standard formula that has been used for the 30+ years I've been doing this, is the standard formula that is close enough for 99% of people. I just did a bunch of basic sizes and every one was the same to the hundredth. If the original poster wanted it exact to the ten thousandth, than I apologize for confusing anyone. I will watch which forum I'm in closer next time.
.
How about we are not trying to make life complicated on the non 140 IQ people or showing off that we are 140+ IQ. I personally was just helping answer a simple ??
We are not trying to avoid anything. The standard formula that has been used for the 30+ years I've been doing this, is the standard formula that is close enough for 99% of people. I just did a bunch of basic sizes and every one was the same to the hundredth. If the original poster wanted it exact to the ten thousandth, than I apologize for confusing anyone. I will watch which forum I'm in closer next time.
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Launching!
Joined: Nov 2005
Posts: 213
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anyway, true displacement is:
(Pi) x (r^2) x (stroke) x (number of cylinders)
r = (Bore) / (2)
Pi = 3.14159
Stroke = Depends on crankshaft
example:
Bore = 4.030"
Stroke = 4.000"
Cylinders = 8
(3.14159) x [(4.030" / 2)^2] x 4.000" x 8
= 408.178ci = 408.178 cubic inches = 408.178 in^3
= 6.688 liters
(Pi) x (r^2) x (stroke) x (number of cylinders)
r = (Bore) / (2)
Pi = 3.14159
Stroke = Depends on crankshaft
example:
Bore = 4.030"
Stroke = 4.000"
Cylinders = 8
(3.14159) x [(4.030" / 2)^2] x 4.000" x 8
= 408.178ci = 408.178 cubic inches = 408.178 in^3
= 6.688 liters
Originally Posted by andereck
Only LS1Tech Advanced Tech could complicate it beyond this.
you know, i think its easier to remember 3.14 then it is to remember a number specific for that one calculation.
:shrug:
in anycase, i guess im lucky i remember basic geometry from elementary school.. it keeps me from having to memorise a specific "easier" formula for everything.... i mean, id need a calculator for both, so its not like its harder.... hell, my calculator (windows calculator) has a Pi button.
TECH Resident
Joined: Oct 2005
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Originally Posted by MrDude_1
you know, i think its easier to remember 3.14 then it is to remember a number specific for that one calculation.
:shrug:
in anycase, i guess im lucky i remember basic geometry from elementary school.. it keeps me from having to memorise a specific "easier" formula for everything.... i mean, id need a calculator for both, so its not like its harder.... hell, my calculator (windows calculator) has a Pi button.
:shrug:
in anycase, i guess im lucky i remember basic geometry from elementary school.. it keeps me from having to memorise a specific "easier" formula for everything.... i mean, id need a calculator for both, so its not like its harder.... hell, my calculator (windows calculator) has a Pi button.
The way I and others do it is easier and is based off of rounding Pi up to 3.1416. .7854 is Pi / 4.
Questions for displacement: what is the bore size? what is the stroke? how many holes?
Bore size - 4.562 (4.562 x 4.562)
Stroke - 4.375 (4.562 x 4.562) * 4.375)
Holes - 8 (((4.562 x 4.562 ) * 4.375)* 8)
Constant - .7854 ((((4.562 x 4.562 ) * 4.375) *8) * .7854) = 572.10
There is no need to find the radius and then do the math.
Your way, oh what are you going to use for Pi? 3.14?
4.562 / 2 = 2.281 ^ 2 = 5.202 * 4.375 * 3.14 = 571.69. I didn't round up since you use 3.14 for Pi.
This is a funny discussion.
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Verdad Gallardo TECH Resident
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Originally Posted by MrDude_1
i kinda stopped reading your reply after you said "find the radius". 
Poor guy who started the thread probably wishes he hadn't.
Originally Posted by andereck
Really? Then why did you pop off a reply and find a cute little smiley?
Poor guy who started the thread probably wishes he hadn't.
Poor guy who started the thread probably wishes he hadn't.
the popping off a reply part is really just a function of me being able to type really really fast.... i also typed the smilie, i dont really use the icons since ive been on here for awhile.
think about this... you're obviously using a calculator, since 95% of us are not doing this on paper longhand... so really it doesnt make much diff..
and fyi, no i dont use 3.14... i just got lazy typing... normally i use 3.14159... because i have it memorized out that far... really, i know the next one is a 2, but if i really needed that number for accuracy, i would just hit the Pi button on the calculator.
heres how id type it...
Bore / 2 =
^2 (the square button.... if not there, then just look at the number, hit x then type it)
* Pi (once more i hit the Pi button, but you can also type 3.14159)
* stroke
* number of cyls...
and i have the number, regardless if its for my streetbike, dirtbike, LS1 or lawnmower.
not once did i have to write anything down, or do anything besides type it in the calculator..... its all linear.
you can do the same with your formula, except you have a constant to remember.
in anycase, its much ado about nothing... if you have to "figure out" the radius, you really dont need to know.
If you don't want to find the radius, then why don't you use:
(pi/4)*(bore)^2*stroke*number of cylinders
Would you build an engine using a tape measure from Wal-Mart to verify the clearances? You should use the proper tools no matter what you are doing...mathematical or otherwise. If your calculator doesn't have a pi button, find one that does.
(pi/4)*(bore)^2*stroke*number of cylinders
Would you build an engine using a tape measure from Wal-Mart to verify the clearances? You should use the proper tools no matter what you are doing...mathematical or otherwise. If your calculator doesn't have a pi button, find one that does.
Originally Posted by ThirdGenLS1
hahaha never thought i would see so much bitching over such a simple equation
Originally Posted by MeentSS02
Well...to say that, you'd really have to define the word "bitching". I'd say I was more butt-hurt than bitchy in my replies...math is my only friend
