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how to add up bore and crank

Posted: Sun Jan 08, 2012 8:32 pm
by FullRace808
How do u add a stroker bore and crank to get your overall cc.
For example. A 50mm fully counter stroker crank.and a 54mm ruima bore. Wat will it turn out too

Re: how to add up bore and crank

Posted: Sun Jan 08, 2012 8:38 pm
by Majourlittle
Since a bore is a cylinder, apply the cyl volume equation. Convert mm to cm and then use

volume = 3.14 x bore x bore x stroke

Re: how to add up bore and crank

Posted: Sun Jan 08, 2012 11:22 pm
by eliteguy50
Majourlittle wrote:Since a bore is a cylinder, apply the cyl volume equation. Convert mm to cm and then use

volume = 3.14 x bore x bore x stroke
No, you want r, not d. It is ¤Ç*half bore*half bore*stroke
So about 114cc

Re: how to add up bore and crank

Posted: Mon Jan 09, 2012 12:41 pm
by Majourlittle
Whops, drunk post. Missed the Pi/4 to get the required circle area.

Volume = 0.785 x bore x bore x stroke.

Re: how to add up bore and crank

Posted: Mon Jan 09, 2012 1:19 pm
by Bear45-70
Majourlittle wrote:Whops, drunk post. Missed the Pi/4 to get the required circle area.

Volume = 0.785 x bore x bore x stroke.
That's the one I like because you don't have to screw around with halving the diameter or Pi. I also use .7854 (to be really accurate use BORE X BORE X STROKE X .7853982) because it is a little more accurate, but the other is close enough for most.

Re: how to add up bore and crank

Posted: Mon Jan 09, 2012 2:26 pm
by devenex
Just being nit-picky here but using more decimal places leads to greater precision, but does not affect accuracy. This is an important distinction made in statistics, but also makes some sense for everyday use of the words.

http://en.wikipedia.org/wiki/Accuracy_and_precision

Re: how to add up bore and crank

Posted: Mon Jan 09, 2012 2:45 pm
by Bear45-70
devenex wrote:Just being nit-picky here but using more decimal places leads to greater precision, but does not affect accuracy. This is an important distinction made in statistics, but also makes some sense for everyday use of the words.

http://en.wikipedia.org/wiki/Accuracy_and_precision
Do not believe everything you read in Wikipedia. Any idiot can post something there, true or not. That being said, "Being precise will always improve accuracy."

Re: how to add up bore and crank

Posted: Mon Jan 09, 2012 3:13 pm
by eliteguy50
Ask any quality control manager, precision and accuracy.are not the same.

Re: how to add up bore and crank

Posted: Mon Jan 09, 2012 3:20 pm
by Bear45-70
eliteguy50 wrote:Ask any quality control manager, precision and accuracy.are not the same.
Read what I said. I did not say they were the same.

Re: how to add up bore and crank

Posted: Mon Jan 09, 2012 3:37 pm
by Bear45-70
Oh and apparently your are wrong.

ac┬Àcu┬ÀrateÔÇé ÔÇé[ak-yer-it]

1.free from error or defect; consistent with a standard, rule, or model; precise; exact.

2.careful or meticulous: an accurate typist.

pre┬Àci┬ÀsionÔÇé ÔÇé[pri-sizh-uhn] noun

1.the state or quality of being precise.

2.accuracy; exactness: to arrive at an estimate with precision.

3.mechanical or scientific exactness: a lens ground with precision.

4.punctiliousness; strictness: precision in one's business dealings.

5.Mathematics . the degree to which the correctness of a quantity is expressed. Compare accuracy ( def. 3 )

Re: how to add up bore and crank

Posted: Mon Jan 09, 2012 5:12 pm
by Majourlittle
If you are using a zero decimal mm mesurement, your signifigant digits is to the 10s place. your accuracy is only going to be to XX.X cm^3. In short, don't worry about the s*** on the end with these small * engines. What you calcuate could be signifigantly off because of assembly/manufacturing/setup error.

I can assure you the first person that tries to swing * on this site for having an engine that is 98.45822cm^3 will be harrased until they wet the bed.

:smile:

Re: how to add up bore and crank

Posted: Tue Jan 10, 2012 12:46 am
by devenex
I just posted the wiki link as a quick guide that popped up on a search.

You can very precisely measure an inaccurate value.

Re: how to add up bore and crank

Posted: Tue Jan 10, 2012 1:15 am
by Bear45-70
devenex wrote:..................................You can very precisely measure an inaccurate value.
Now there is an oxymoron if there ever was one. :roll:

Re: how to add up bore and crank

Posted: Tue Jan 10, 2012 1:24 am
by devenex
It would be if the words were the same.

Since you're so opposed to anything wiki maybe this will help convince you:
http://scidiv.bellevuecollege.edu/physi ... c-unc.html

Re: how to add up bore and crank

Posted: Tue Jan 10, 2012 10:08 am
by Majourlittle
There is a world of difference between 6miles and 6.00miles. They may look the same to you, but if I told someone that I was lost in the woods...

If I said that I was 6 miles from some point, that would mean that I was within 5.5 miles and 6.5 miles of that point Thats a total of 1 mile error

If I said that I was 6.00 miles from some point, that would mean that I am 5.95 miles and 6.05 miles from that point. Thats a total of 0.1 mile error

Which person would be found first?

You are only as accurate as your innacurate number. This is basic physics. This is undeniable. If you disagree with me, please provide supporting and reliable references.