what is the formula for cubic inches?

JM90GT · 03-06-2002, 04:31 PM

I may be behind the power curve here but how do you figure out cubic inches? (for example: the 377 for project death machine) I heard it's like bore (stroke)=x then divide x by number of cylinders, but my math doesn't come out right. Is this correct?

fiveohpatrol · 03-06-2002, 05:56 PM

Its just the volume of all the cylinders you have.
Volume of a cylinder is area*height
The height of the cylinder is the stroke, and the area is the area of the top of the piston which is Pi*(1/2*bore)^2 (Pi is approx=3.14)
then multiply by the number of cylinders you have, which in any car that you'd care about figuring out the displacement is 8 or higher.

so on a 302 (4" bore, 3" stroke) its--> 3.14*(1/2*4)^2 * 3 * 8 = 301.44, round up to 302

using a more accurate value of Pi will yield a more accurate answer, for instance using Pi=3.141592654 will give you 301.5928949 sq in

hope this helps

andy669 · 03-06-2002, 08:02 PM

I like to simplify things alittle.... hehehe I use bore* bore* stroke* number of cylinders* .7854.
Are there any more?

andy

JM90GT · 03-06-2002, 09:06 PM

Ah, I thought there was probably more to it. Still a little fuzzy but I'll run through it a few time's thanks.

Fiveohpatrol, what are you? lol. But that's what we all want... the answer's.

fiveohpatrol · 03-06-2002, 09:10 PM

I'm a Mechanical Engineering undergrad, that explains alot of the rambling that I do

Fox Body · 03-06-2002, 10:13 PM

I like the "rambling". It's cool. I wish more people would take the time to explain things rather than assume everyone knows what they're talking about and taking the quick and easy route (all though of course that is sometimes better--depending on the situation).

PKRWUD · 03-07-2002, 05:38 AM

Fox Body-

Happy 1200!

Take care,
-Chris

cyberstang5.0 · 03-07-2002, 08:14 AM

PKRWUD

Happy 3100

PKRWUD · 03-07-2002, 10:24 AM

Far out! I didn't even notice that. Thanks!

Take care,
-Chris

Fox Body · 03-07-2002, 06:09 PM

Quote:

Originally posted by PKRWUD
Fox Body-
Happy 1200!
Take care,
-Chris

Well crap! I didn't even notice

Thankye

cyberstang, happy, uh...242...

03-06-2002, 04:31 PM	#1
JM90GT Registered Member Join Date: Dec 2000 Location: Bartlesville OK Posts: 68	what is the formula for cubic inches? I may be behind the power curve here but how do you figure out cubic inches? (for example: the 377 for project death machine) I heard it's like bore (stroke)=x then divide x by number of cylinders, but my math doesn't come out right. Is this correct?

03-06-2002, 05:56 PM	#2
fiveohpatrol I'd rather be basketweaving Join Date: Feb 2000 Location: Indianapolis Posts: 2,551	Its just the volume of all the cylinders you have. Volume of a cylinder is areaheight The height of the cylinder is the stroke, and the area is the area of the top of the piston which is Pi(1/2bore)^2 (Pi is approx=3.14) then multiply by the number of cylinders you have, which in any car that you'd care about figuring out the displacement is 8 or higher. so on a 302 (4" bore, 3" stroke) its--> 3.14(1/24)^2 3 * 8 = 301.44, round up to 302 using a more accurate value of Pi will yield a more accurate answer, for instance using Pi=3.141592654 will give you 301.5928949 sq in hope this helps __________________ NMRA O/C 9516 NA pumpgas stickshift 347 10.65@125.6, 6.73@100, 1.41 60ft

03-06-2002, 08:02 PM	#3
andy669 Registered Member Join Date: Jan 2001 Location: Moline Il Posts: 901	I like to simplify things alittle.... hehehe I use bore* bore* stroke* number of cylinders* .7854. Are there any more? andy __________________ 88 coupe 91 LX NMRA Pure Street 5120

03-06-2002, 09:10 PM	#5
fiveohpatrol I'd rather be basketweaving Join Date: Feb 2000 Location: Indianapolis Posts: 2,551	I'm a Mechanical Engineering undergrad, that explains alot of the rambling that I do __________________ NMRA O/C 9516 NA pumpgas stickshift 347 10.65@125.6, 6.73@100, 1.41 60ft

03-06-2002, 10:13 PM	#6
Fox Body Mustang Maniac Join Date: Sep 2000 Location: GA, U.S.A Posts: 2,266	I like the "rambling". It's cool. I wish more people would take the time to explain things rather than assume everyone knows what they're talking about and taking the quick and easy route (all though of course that is sometimes better--depending on the situation). __________________ 351W-powered 1979 Ford Mustang Ghia notchback '79 Video @ Idle Stock 5.8L under 4" cowl 'glass hood, C4 w/ Transgo shift kit, Holley 750 cfm, Edelbrock Performer RPM intake; Fluidyne Al radiator, Flexalite 175 electric fan, 1 5/8" MAC shorty headers, FRPP Al driveshaft; S&W 6-point cage; 2.5" Off road H-pipe, 2-chamber Flowmasters, 8.8" Rear w/ 3.55s; Weld wheels (15x6;15x8), Front: 225/60/15, Rear: 275/50/15 Nitto NT 555R Drag Radials; 14 x 4” K&N X-stream air filter. '92 GT (5-speed) Small In Car Video Stock 5.0L, 2-chamber Flowmasters, MAC CAI, Tri-Ax, Al pedals... "Red, thou art my companion. Hasten now your quickened metamorphosis to Green that I may conquer all who dare abide there beside me. May they be left thither behind burnt black." ---Fox Body

03-06-2002, 09:06 PM	#4
JM90GT Registered Member Join Date: Dec 2000 Location: Bartlesville OK Posts: 68	Ah, I thought there was probably more to it. Still a little fuzzy but I'll run through it a few time's thanks. Fiveohpatrol, what are you? lol. But that's what we all want... the answer's.

03-07-2002, 05:38 AM	#7
PKRWUD Junior Member Join Date: Mar 1999 Location: Ventura, California Posts: 8,981	Fox Body- Happy 1200! Take care, -Chris __________________ Webmaster: Rice Haters Club Jim Porter Racing Peckerwoods Pit Stop Support Your Local RED & WHITE!

03-07-2002, 08:14 AM	#8
cyberstang5.0 347ci of HORSE POWER!!! Join Date: Jul 2001 Location: Houston, TX Posts: 1,416	PKRWUD Happy 3100

03-07-2002, 10:24 AM	#9
PKRWUD Junior Member Join Date: Mar 1999 Location: Ventura, California Posts: 8,981	Far out! I didn't even notice that. Thanks! Take care, -Chris __________________ Webmaster: Rice Haters Club Jim Porter Racing Peckerwoods Pit Stop Support Your Local RED & WHITE!

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