C.I. Displacement

[WEEZER]

What's the formula to figure out the ci if you bore out a block, say a 350 small block chevy bored .040. I know that a 350 .030 over is a 355 ci.
Thanks.

[jimmy'z]

Displacement = pi/4 X bore (squared) X stroke X no. of cylinders

pi=3.14159

( I'd do the math, but do not know stroke value )

[W. J.]

A wild guess would put it at about 358ci.

[richardpetey]

Chevy 358ci is a .060 overbore(4.060)......................... :rolleyes:
UNCLE PETEY.................. :wave: :wave: :wave: :wave: :wave:

[BOWATCHER]

example4.040x4.040x.7854x3.48x8=356.88ci
bore sq.x1/4 pie x strokex no. of cyl.=
hope this helps :cheers:

[IDRIVEALARGECAR]

it all depends on the stroke/rod size with stock sized rods its actually 356.150 then if you have .250 longer rods it will bring to almost 359.750 so you would have to know all the particulars as far as stroke and rod length.
Joey Colicchio

[BOWATCHER]

Hey Joey check them batteries in that calculator/356.88 rod length doesn't effect cubes crankshaft stroke dictates cubes. ps 120,000 or 80,000 gvw in NC? take care man!!!!

[IDRIVEALARGECAR]

And i hung up my keys i dont drive anymore i started my own buisness with my fiancee and it is starting to do well. and when you stroke a motor not only do you use a bigger crank you can also use longer rods therefore you need to determine that when you figure out the cubic inches that is what i always thought. but hey i could be wrong. a normal 350 starts out at 3.900 or something and when you go .030 over it goes to 3.989. and 354 cubic inches so i always thought that stroke added to the cubic inches also. when you coming to visit Frank i aint seen you in a while come down for the N/S shoot out and stay by me we will have a blast. Later on and be cool
Joey Colicchio

[RGeeProductions]

This is funny as I worked at a shop for 1 1/2 years and had same argument with my boss. He said longer rod means more stroke. I told him, the crank determines stroke not the rod. He still said nope. Told him take a 2 stock 350ci chevy motor. Put 5.75 in. rod in one, 6 in. in the other, is there a difference in stroke between them now? They both still travel the same distance........

[BOWATCHER]

stock stroke sbc 350=3.48 rod length affect means the piston is parked in thecombustion chamber longer or shorterwith different rod lengths for different torque characteristics stick with a 5.7 rod for the Head JMO

[IDRIVEALARGECAR]

Ok all different scenarios Frank call me at my office one day during the week OK it would be great to talk to you. 704-257-6517
Joey Colicchio www.funoutdoorliving.com

[SBMotorsports]

the correct formula is Bore x Bore x stroke of crankshaft x .7854 x Number of cylinders= CID rod length has nothing to do with CID

[IDRIVEALARGECAR]

OK Fella's here is the master list from GM performance Parts you can figure everything out from here Joey Colicchio
262 = 3.671" x 3.10" (Gen. I, 5.7" rod)
265 = 3.750" x 3.00" ('55-'57 Gen.I, 5.7" rod)
265 = 3.750" x 3.00" ('94-'96 Gen.II, 4.3 liter V-8 "L99", 5.94" rod)
267 = 3.500" x 3.48" (Gen.I, 5.7" rod)
283 = 3.875" x 3.00" (Gen.I, 5.7" rod)
293 = 3.779" x 3.27" ('99-later, Gen.III, "LR4" 4.8 Liter Vortec, 6.278" rod)
302 = 4.000" x 3.00" (Gen.I, 5.7" rod)
305 = 3.740" x 3.48" (Gen.I, 5.7" rod)
307 = 3.875" x 3.25" (Gen.I, 5.7" rod)
325 = 3.779" x 3.622" ('99-later, Gen.III, "LM7", "LS4 front wheel drive V-8" 5.3 Liter Vortec, 6.098" rod)
327 = 4.000" x 3.25" (Gen.I, 5.7" rod)
345 = 3.893" x 3.622" ('97-later, Gen.III, "LS1", 6.098" rod)
350 = 4.000" x 3.48" (Gen.I, 5.7" rod)
350 = 4.000" x 3.48" ('96-'01, Gen. I, Vortec, 5.7" rod)
350 = 3.900" x 3.66" ('89-'95, "LT5", in "ZR1" Corvette 32-valve DOHC, 5.74" rod)
364 = 4.000" x 3.622" ('99-later, Gen.III, "LS2", "LQ4" 6.0 Liter Vortec, 6.098" rod)
376 = 4.065" x 3.622" (2007-later, Gen. IV, "L92", Cadillac Escalade, GMC Yukon)
383 = 4.000" x 3.80" ('00, "HT 383", Gen.I truck crate motor, 5.7" rod)
400 = 4.125" x 3.75" (Gen.I, 5.565" rod)
427 = 4.125" x 4.00" (2006 Gen.IV, LS7 SBC, titanium rods)

Two common, non-factory smallblock combinations:

377 = 4.155" x 3.48" (5.7" or 6.00" rod)
400 block and a 350 crank with "spacer" main bearings
383 = 4.030" x 3.75" (5.565" or 5.7" or 6.0" rod)
350 block and a 400 crank, main bearing crank journals
cut to 350 size
The 355 small block combo wasn,t as popular as some so it isn't listed but it is a .030 350 with standard sized rods and crank according to the GM rep that emailed me this info

[W. J.]

Wow, Joe, Thanks for the info. We can always count on our fellow posters for the best information.

[art11758]

The connecting rod length changes the amount of time the piston spends at TDC IIRC. I remember it being referred to as "dwell time". It also requires the use of a piston with the pin bore in a different location. A simple explanation is it changes the torque characteristics of a given combination. Of course no single change is the "end". Camshaft selection and a host of other things all work towards that.
To answer the original question in laymans terms (which has been answered correctly several times):
Bore or diameter of the cylinder squared multiplied by .7854 equals area.
Multiply the area times the stroke and you get the volume/displacement of a/the cylinder.
Multiply by the number of cylinders and you get displacement of the engine.
You can measure all of these accurately with a vernier caliper and a set of telescoping gauges.

[jimmy'z]

The connecting rod length changes the amount of time the piston spends at TDC IIRC.

Doesn't the crank dictate the time spent at TDC ? The rod length only changes the length of piston stroke through the cylinder and once a piston hits TDC the rotation of the crank's diameter than pulls it back down....also, IIRC.

I have to dig out my books. Also going to go ask a former gearhead here at work to confirm if what I said is true.

[jimmy'z]

:confused: ... nice picture of the motor...you can keep the pedantic dialogue up above..

Art11785; I found an old book with all that motor stuff in it; thanks for giving me some ideas on lunchtime reading :D It'll help clear things up on my end.

[art11758]

Imagine if you will that 1/2 of the motion of the connecting rod on the big end of every rotation of the crankshaft is similar to a triangle. If the triangle has a known height,(think stroke) then the only thing that can change if you extend the two legs (think connecting rod CTC) is the width of the base. If you think of that distance as time you will see what I was trying to explain. Remember too that long rod combos usually increase the load on the mains while creating all of this "power". And if all this "illustration" doesn't make any sense... I'm sorry. Did my best to explain it in a verbal illustration.
jimmy'z: glad to be of help. I love thinking and planning and building....