What is my CID?

[jdiesel33]

I have a 440 in my '68 and it was bored 40 over. Can someone tell me what the new cid is? i think the calculation is bore x stroke x 8, maybe? However I dont know exactly what to put in for the bore and stroke.

[adauto]

Well .30 over would make a 446. There's a formula for this , but I just dont remember it.

[6pkrunner]

The formula is pi/4 x bore x bore x stroke x number of cylinders.

3.1416/4 x 4.32 x 4.32 x 3.75 x 8 = 439.723 for stock 4.32 bore

3.1416/4 x 4.34 x 4.34 x 3.75 x 8 = 443.804 for 0.020 over

3.1416/4 x 4.35 x 4.35 x 3.75 x 8 = 445.851 for  0.030 over

3.141.6/4 x 4.36 x 4.36 x 3.75 x 8 = 447.904 for 0.040 over

3.1416/4 x 4.38 x 4.38 x 3.75 x 8 = 452.022 for 0.60 over

[oldschool]

another one is:

bore x bore x stroke x .785 = cid for each cylinder. then just  mulitply by no. of cylinders.

your case: 4.360 x 4.360 x 3.75 x .785 =55.95 ci. per cyl x8 = 447.67 cid.

[Dino]

Guess I have a 444 then!  My engine has the mark on the id pad that says it's 20 over, not sure why.

[jdiesel33]

Thanks fellas. Those are good formulas to have on hand.

[jdiesel33]

The formula is pi/4 x bore x bore x stroke x number of cylinders.

3.1416/4 x 4.32 x 4.32 x 3.75 x 8 = 439.723 for stock 4.32 bore

3.1416/4 x 4.34 x 4.34 x 3.75 x 8 = 443.804 for 0.020 over

3.1416/4 x 4.35 x 4.35 x 3.75 x 8 = 445.851 for  0.030 over

3.141.6/4 x 4.36 x 4.36 x 3.75 x 8 = 447.904 for 0.040 over

3.1416/4 x 4.38 x 4.38 x 3.75 x 8 = 452.022 for 0.60 over

Maybe I should get the hood black out stickers and then get stickers to put on those that say "447.904 c.i." .

[adauto]

    

[John_Kunkel]

Guess I have a 444 then!  My engine has the mark on the id pad that says it's 20 over, not sure why.

The engine plant made some sort of a boo-boo and, rather than scrap the block, they bored it .020" over.
Ditto for oversized lifters and undersized cranks.

[Budnicks]

Isn't the easy formula actually ; bore ( 4.32"+0.040" = 4.36" ) X bore ( 4.36" ) X stroke ( 3.75" ) X number of cylinders ( 8 ) X .7854 = CID 447.90419ci   {That way you don't need to know what pi/4 is}...

[A383Wing]

CID = 3.1415926 x (Bore/2 x Bore/2) x stroke x number of cylinders

This is what I have always used....I can't find the "PIE" key on my keyboard

Bryan

[mhinders]

CID = 3.1415926 x (Bore/2 x Bore/2) x stroke x number of cylinders

This is what I have always used....I can't find the "PIE" key on my keyboard

Bryan

I agree with you Bryan, why make a simple, basic formula complicated?
Martin

[404NOTFOUND]

The formula is pi/4 x bore x bore x stroke x number of cylinders.

3.1416/4 x 4.32 x 4.32 x 3.75 x 8 = 439.723 for stock 4.32 bore

3.1416/4 x 4.34 x 4.34 x 3.75 x 8 = 443.804 for 0.020 over

3.1416/4 x 4.35 x 4.35 x 3.75 x 8 = 445.851 for  0.030 over

3.141.6/4 x 4.36 x 4.36 x 3.75 x 8 = 447.904 for 0.040 over

3.1416/4 x 4.38 x 4.38 x 3.75 x 8 = 452.022 for 0.60 over

Maybe I should get the hood black out stickers and then get stickers to put on those that say "447.904 c.i." .

I like that idea. Don't forget to do updates for bore wear. You should be able to run 448 stickers around the 15,000 mile mark.

[john108]

That is pretty good for pie, if you don't mind round-off error.

I use: 3.14159265358979323846264338327950288 when I am in a hurry.

[Cooter]

I just tell people when they ask about what Cu. In. my final engine build is, that it's just "BIG".
I also like telling them that I "Bored this thing all the way out to a 500" motor" that one really gets 'em talking.

[mhinders]

That is pretty good for pie, if you don't mind round-off error.

I use: 3.14159265358979323846264338327950288 when I am in a hurry.

It's that kind of rounding off that causes space crafts to get lost in space! 

[doctor4766]

I never was too good with math.
Can someone tell me what a 383 with a 0.30 over bore would equate to please?

[A383Wing]

I never was too good with math.
Can someone tell me what a 383 with a 0.30 over bore would equate to please?

I assume you mean .030" overbore, not 0.30 as you posted

.030" overbore is 387.44 using my formula above...

Bryan

[doctor4766]

I never was too good with math.
Can someone tell me what a 383 with a 0.30 over bore would equate to please?

I assume you mean .030" overbore, not 0.30 as you posted

.030" overbore is 387.44 using my formula above...

Bryan

Thanks for that Bryan 

[mhinders]

CID = 3.1415926 x (Bore/2 x Bore/2) x stroke x number of cylinders
This is what I have always used....I can't find the "PIE" key on my keyboard
Bryan

Hey Bryan, have you noticed that today is "pie-day", date is 3.14           

[A383Wing]

I like pie......

apple pie

Bryan (and in about a month, it will be Hemi day - 4-26)