Cubic Inch Formula ?

[sawtooth]

Looking for a little help here, what is the formula to figure out the cubic inchs of a motor like when you want to make one bigger. It was something like stroke x rod length x cylinder diameter x blah blah blah = cubic inch. It was explained to me years back and I will be damed if I can remember.....should have wrote it down. Thanks to all the smart guys that can help me with this.

[Fiat48]

Bore x Bore x stroke x7854 x # of cylinders.

[Oldsquirt]

Sawtooth, check out the first thread in this forum. It is called "Tech Links". There are links there to tons of info including this. BRC Engine Calculators (http://www.brcperformance.com/enginecalc.htm)

[BDMar]

CI = (bore/2 x bore/2) x 3.1416 x stroke x # of cylinders
Ex:
4.500 bore
4.250 stroke
(2.250 x 2.250) = 5.063
5.063 x 3.1416 = 15.906
15.906 x 4.250 = 67.601
67.601 x 8 = 540.808 CI

[BDMar]

HAHA Two replies while I was typing my formula!! :D

[BDMar]

Bore x Bore x stroke x7854 x # of cylinders.
I think you meant .7854

[Infomaniac]

What they said... Or go here
http://brcpistons.com/enginecalc.htm
Or Use This... http://marineassault.net/211CID_Chart.jpg

[superdave013]

Radius of cylinder squared X pie X # of cylinders.
Not bad for a guy who's math classes were always right after lunch. :D

[obnoxious001]

Radius of cylinder squared X pie X # of cylinders.
Not bad for a guy who's math classes were always right after lunch. :D
You have been eating too much PIE!
That formula gives you the total surface area of the tops of the pistons if they were flat tops with no valve reliefs. pi x r squared gives you the area of a circle.

[River Rat 005]

Superdave you must have been late that day. You need X stroke=cid

[superdave013]

Oh yes, I forgot the height. opps

[superdave013]

Radius of cylinder squared X pie X # of cylinders.
Not bad for a guy who's math classes were always right after lunch. :D
Radius of cylinder squared X pie X height (stroke) X # of cylinders.
There, all better. :)

[Infomaniac]

Bore squared x 1/4 pie (.7854) x stroke x # of cylinders. :D

[Fiat48]

Hmm. Perhaps I was not the only one who tuned up the math teachers car in order to pass the class. :D
(I really did that). LOL

[CARLSON-JET]

Do these formulas work on a rotory?? :D :D

[SmokinLowriderSS]

Radius of cylinder squared X pie X # of cylinders.
Not bad for a guy who's math classes were always right after lunch. :D
Yep, you got it PARTLY right. LOL
Pi-x-(RXR)-x-Height-x-# of cylinders.
Radius of cylinder times radius of cylinder, then times 3.15159 etc,etc,etc then times the piston stroke, then times # of cylinders.
Or just use the easy ways of a computer program. :D

[superdave013]

R squared is the same as R x R right?
And yes, I did leave off the height on my first go around. You are late on that correction. obnoxious001 already got that pie. :)

[sawtooth]

Thanks for all the replys there gang, now can anyone tell me what the stock bore and stroke on a BBC 454ci motor is. Lets say it has a 4.500 bore and the stroke is 4.000, to get it to a 540ci it would need a .250 longer stroke. Can this be done with a longer rod or does it have to be done with a stroker crank shaft. With the longer rod it would put the piston out of the block that much farther so could you have the piston made with a different pin loaction or is this defeating the purpose. If you change the crank (.250 stroker) does this change the deck hight of the piston. I should have payed more attention hanging out in the garage with the ol' engine builder back in the day. Thanks again.

[Oldsquirt]

Thanks for all the replys there gang, now can anyone tell me what the stock bore and stroke on a BBC 454ci motor is. .
454 = 4.250" bore x 4.00" stroke
Lets say it has a 4.500 bore and the stroke is 4.000, to get it to a 540ci it would need a .250 longer stroke. Can this be done with a longer rod or does it have to be done with a stroker crank shaft
Stroke is determined by the crankshaft, not the connecting rod.
BTW, 4.5 bore and 4.00 stroke = 509
With the longer rod it would put the piston out of the block that much farther so could you have the piston made with a different pin loaction or is this defeating the purpose..
Yes pin location must be changed to match the combination of stroke/rod length/block deck height.
If you change the crank (.250 stroker) does this change the deck hight of the piston. .
Yes, if you use a .250" stroker crank with the stock rods and pistons, the piston will be sticking out of the hole (approximately .125").

[SmokinLowriderSS]

Yes, if you use a .250" stroker crank with the stock rods and pistons, the piston will be sticking out of the hole (approximately .125").
Just use 3 head gaskets and you'll be fine. :D :D

[Moneypitt]

Just use 3 head gaskets and you'll be fine. :D :D
Yeah that used to work, but you needed 5 3/4 intake gaskets per side, and you just can't find those 3/4 intake gaskets anymore....5 is too thin, and 6 is too thick........So whatta ya gonna do?.........MP

[SmokinLowriderSS]

R squared is the same as R x R right?
And yes, I did leave off the height on my first go around. You are late on that correction. obnoxious001 already got that pie. :)
Yep, I was a bit slow, and shoulda used the scroll wheel a bit farther before using the keyboard. :D :D

[SmokinLowriderSS]

Yeah that used to work, but you needed 5 3/4 intake gaskets per side, and you just can't find those 3/4 intake gaskets anymore....5 is too thin, and 6 is too thick........So whatta ya gonna do?.........MP
5 gaskets, 3 swipes from the roll of Duck Tape, and RTV just fer good measure. :D :D :D
Did people actually stack intake gaskets to make up on a tall-deck block in "The Old Days"?

[Moneypitt]

5 gaskets, 3 swipes from the roll of Duck Tape, and RTV just fer good measure. :D :D :D
Did people actually stack intake gaskets to make up on a tall-deck block in "The Old Days"?
No......But the gasket was the only pattern to use when making the spacers. But I was only a child back then.......The fun part was the extra bore in the extention plates for a huge stroked SBC.....427 inches from a Small Block.........MP