Help on figuring CID

[Red73BB]

My 454 is bored 30 over. How do I calculate my CID. :confused
Thanks in advance,
Gary

 

[Jack]

I looked it up in a trw-speedpro piston book ... thirty over 454 is 460ci. Stock bore & stroke = 4.250" x 4.000".

BTW ... the CID calculator here on CACC site is pretty lame. http://corvetteactioncenter.com/tech/tools/displacement.html#
Its stroke is limited to 100mm (stock 454 is 101.6mm/4") ... and it requires a conversion to metric before data can be entered ... and it does not accept decimals ... not user-friendly for most US citizens.
JACK:gap

 

[Red73BB]

Jack,
Bear with me, If you take 4.25 X 4.00, this equals 17 X 8 = 136. How does this add up to 454.
Using the caculator you need deck height, Compression Ratio and Combustion Chamber CC's, none that I know.
There has to be a easier way.
Gary

 

[Red73BB]

If you took 454 * .03 =467.62 or 468 CID this make more scents to me.

 

[MaineShark]

CID = 2 * stroke * pi * bore * bore

So, your engine has a bore of 4.28" (4.25+0.03) and a stroke of 4", your displacement is 2 * 4 * 3.14159 * 4.28 * 4.28

= 460.39 cubic inches

Joe

 

[mfendley]

To calculate the volume of a cylinder, you multiply the surface area of the bore (pi*r^2) times the stroke. For the stock bore of 4.25, r=2.125, so pi*r^2=14.186, multiply that times the stroke (4") to get 56.745, and then multiply that by 8 cylinders to get 453.96 cubic inches. If you change the bore to 4.28 inches (.030 over) then pi*r^2 is 14.387, the stroke is the same 4" for 57.549 cubic inches per cylinder, and a total displacement of 460.39. Multiplying by .03 (1.03 actually) increases the total displacement by 3%.


oops, someone beat me to the math while I was typing:J

 

[Jack]

Thanks Rob ... NEW CID calc works great!

BTW ... the CID calculator here on CACC site is pretty lame. http://corvetteactioncenter.com/tech/tools/displacement.html#
JACK:gap

Please note that Rob has replaced the CID calculator with a MUCH improved one! This new one works great! It's at same link ... but it's all new & improved ... Thanks Rob!

BTW ... when using the new tool to calculate static compression ratio ... remember to ADD whatever dish/valve relief volume your pistons may have to the combustion chamber volume. If you have 76cc chamber heads PLUS 12cc piston dish, you'll input 88cc for the combustion chamber volume. If you have a dome or popup piston, you'll SUBTRACT dome volume from comb cham cc ... 76cc heads MINUS 10cc popups = 66cc input. New calculator works great this way too.

Gary ... my apology ... where I wrote 4.250 x 4 .... I simply meant 4.250 "BY" 4 ... I did not mean that it was to be multiplied ... although the way I wrote it sure did look that way ... my bad.

Joe & mfendley have the math right ... and so does the NEW CID calc.
JACK:gap

 

[Red73BB]

Thanks, Jack, Joe and Mike.