Why don't you give it a try? No names, just grades. Seven posters, you included, and one repeat. Jim
Because I'm a professional grader and this is a hobby. My post has typos so I wouldn't give myself anything higher than a C. It's not just math, gotta include communications.
JBradley500 also has a correct formula as 0.7854 = PI/4, so this constant includes the conversion of diameter into radius.
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i always use .7854 because i think of a circle and a square with the same diameter... if both were 4" diameters then the circles area would be 4*pi=12.56... and the square would be 4*4=16... 12.56.../16=.7854 this means a circle has 78.54% of the area of a square if they both had the same diameter, and since a piston is in a circle shape it only makes sence.
this is the reason the formula makes sence and i use it because it makes sence to me lol
The grades are in after my initial post with the formula: 3 get an 'A' 1 gets a 'B' 1 gets a 'D' 2 get an 'F' There was one repeat entry. As I said - 'Remember all that crap they taught you in school', evidently not. Comments Glen? Jim
I suck at math. 292 and change sounds about right, but how does that affect the horsepower? OK math gurus. You have gone from 289 cubic inches to 292 by boring 0.030 over. Now, how much horsepower have you added to that engine if any? Show each step of the math.
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Joined: 1/18/2007 From: Las Cruces, NM Status: offline
quote:
ORIGINAL: Soaring
quote:
ORIGINAL: 66GTKFB
The grades are in after my initial post with the formula: 3 get an 'A' 1 gets a 'B' 1 gets a 'D' 2 get an 'F' There was one repeat entry. As I said - 'Remember all that crap they taught you in school', evidently not. Comments Glen? Jim
I suck at math. 292 and change sounds about right, but how does that affect the horsepower? OK math gurus. You have gone from 289 cubic inches to 292 by boring 0.030 over. Now, how much horsepower have you added to that engine if any? Show each step of the math.
292.87 divided by 288.52 = 1.015% increase in displacement, assuming 300 HP with standard bore = 304.5 HP assuming all efficiency issues remain constant, and proportional increase in power,,, ... so 4.5 HP???
< Message edited by JMD -- 6/20/2007 4:15:24 PM >
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66 Coupe I-6 Conversion, 408 Windsor, Tremec TKO 600 Wilwood fronts, SSBC Rears 9" Track Loc.
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Joined: 1/18/2007 From: Las Cruces, NM Status: offline
quote:
ORIGINAL: Soaring
Thanks James.....that sounds about right. You'd be surprised at what some guys will do to their engines to gain 4.5 horsepower.
Yea it is crazy, I never bore an engine that dosen't need to be bored, I guess if I were running Nascar or somthing, 4.5 horsepower might make a difference, but for a street car? I don't think so!!
I have a 1970 396 (really a 402) in my garage, it still has a stock bore, It was not easy finding off the shelf standard pistons for an engine of this vintage, and limited production.
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66 Coupe I-6 Conversion, 408 Windsor, Tremec TKO 600 Wilwood fronts, SSBC Rears 9" Track Loc.
I love these responses suggesting I should have known what the bore and stroke is on a 289, and that I should automatically know the formula to figure out displacement. If I knew, I wouldn't be asking. I thought this was a dicussion board, for questions and answers.
Thanks to those who gave a respectful answer. And no, I don't care about the added horsepower, I was just curious. I come from the Chevy school of rebuilding. (rebuilding a 350? Make it a 355 for the heck of it!)
Well there's a couple of things going on here. First, it doesn't matter what the displacement is if you bore the engine .3 over because you have ruined the block!! Boring is done in hundredths of an inch so the question should be about boring 0.030". That extra zero between the decimal point and the 3 makes a big difference.
I love these responses suggesting I should have known what the bore and stroke is on a 289, and that I should automatically know the formula to figure out displacement. If I knew, I wouldn't be asking. I thought this was a dicussion board, for questions and answers.
Thanks to those who gave a respectful answer. And no, I don't care about the added horsepower, I was just curious. I come from the Chevy school of rebuilding. (rebuilding a 350? Make it a 355 for the heck of it!)
Just sit back and let us work. You will eventually get the answer you are looking for. Have fun watching us trip over our tongues.
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Joined: 1/18/2007 From: Las Cruces, NM Status: offline
quote:
ORIGINAL: 65Raven65
I love these responses suggesting I should have known what the bore and stroke is on a 289, and that I should automatically know the formula to figure out displacement. If I knew, I wouldn't be asking. I thought this was a dicussion board, for questions and answers.
Thanks to those who gave a respectful answer. And no, I don't care about the added horsepower, I was just curious. I come from the Chevy school of rebuilding. (rebuilding a 350? Make it a 355 for the heck of it!)
If my posts offended you in any way I apologize, it was not my intent to be condescending or a smart ass in any way shape or form, it did not even occur to me that my posts would sound this way to anyone.
I think I was more into showing of my computer displacement application than anything else, and then I just followed the conversation. I intended no disrespect whatsoever....
And,, BTW, the Ford stuff is new to me as well. (and yes, a .030 overbore is not an issue with most SBC)
James,
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66 Coupe I-6 Conversion, 408 Windsor, Tremec TKO 600 Wilwood fronts, SSBC Rears 9" Track Loc.
65 Raven......we most likely have the most intelligent tech guys on here than any other classic Mustang site. My suggestion, and this is a suggestion that I give everybody, is that you do some research on your own by hitting google and going to the search feature on this forum before you ask a question on the forum so that you are well informed ahead of time about all the nomenclature of part names, etc. Once you get into the ballpark of what you are asking but stilll have to clean up a few things, then come on here and ask your question. Understand that this site is run by volunteers, and all the answers you are getting are volunteered answers.
< Message edited by Soaring -- 6/20/2007 7:28:59 PM >
It'd be a little more power due to the increase in the compression ratio. For a 289 with 54cc heads and a .039" head gasket height, zero deck height, and zero piston dish, the compression ratio from boring the engine from 4.000" to 4.030" would go from 10.528 to 10.652. Also forgotten, the actual bore of the engine will not be 4.030 inches, but something a tad bit more to accomodate the pistons. My 302 is borded out to 4.033 inches.
Well there's a couple of things going on here. First, it doesn't matter what the displacement is if you bore the engine .3 over because you have ruined the block!! Boring is done in hundredths of an inch so the question should be about boring 0.030". That extra zero between the decimal point and the 3 makes a big difference.
*rolls eyes*
You knew what I meant
Gosh, I'm sorry that I lack the clairvouyant ability to properly identify your automotive knowledge when you ask such a basic question. Your mistake is a common one and I thought it may be beneficial to clarify the point, if not for your benefit, then for the benefit of a real newbie who may be reading the thread. Other common mistakes are asking about a V6 and a "posi" rearend in a classic mustang.
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Joined: 11/9/2006 From: South Shores, CA Status: offline
quote:
ORIGINAL: 65Raven65
I love these responses suggesting I should have known what the bore and stroke is on a 289, and that I should automatically know the formula to figure out displacement. If I knew, I wouldn't be asking. I thought this was a dicussion board, for questions and answers.
Thanks to those who gave a respectful answer. And no, I don't care about the added horsepower, I was just curious. I come from the Chevy school of rebuilding. (rebuilding a 350? Make it a 355 for the heck of it!)
Sorry Raven, we were just messing around ... at least a little bit. Seriously, I think some were just surprised that the math behind calculating the volume of a cylinder was not common knowledge, not that people haven't memorized the bore and stroke of a 289. Speaking for myself only, I sometimes forget that many people who don't use this stuff forget it if they don't use it ... kind of like I did with 4 semesters of Calculus.
Well there's a couple of things going on here. First, it doesn't matter what the displacement is if you bore the engine .3 over because you have ruined the block!! Boring is done in hundredths of an inch so the question should be about boring 0.030". That extra zero between the decimal point and the 3 makes a big difference.
*rolls eyes*
You knew what I meant
Gosh, I'm sorry that I lack the clairvouyant ability to properly identify your automotive knowledge when you ask such a basic question. Your mistake is a common one and I thought it may be beneficial to clarify the point, if not for your benefit, then for the benefit of a real newbie who may be reading the thread. Other common mistakes are asking about a V6 and a "posi" rearend in a classic mustang.
Its not the lack of "clairvouyant abilty" that was the problem. It was the condesending sarcasm.
Printable Version
RE: What the cubic inches on a .30 over 289? - 
My post has typos so I wouldn't give myself anything higher than a C. It's not just math, gotta include communications. 
292 and change sounds about right, but how does that affect the horsepower? OK math gurus. You have gone from 289 cubic inches to 292 by boring 0.030 over. Now, how much horsepower have you added to that engine if any? Show each step of the math.
