displacment question

[iroczman]

What would 40 over on a chevy 350 be? I was thinking like 357 c.i.d. I'm not sure.

[ct91rs]

Originally Posted by iroczman

What would 40 over on a chevy 350 be? I was thinking like 357 c.i.d. I'm not sure.

Simplest equation:

Bore x Bore x Stroke x (pi x 2) = Engine Displacement

4.04 x 4.04 x 3.48 x (pi x 2) ≈ 356.88

So yes, you would call it a 357.

[iroczman]

Thanks

[92zcamaroperson]

that would be cool....a little different....however would that be cutting the cylinder walls to thin? Cutting into water jacket thin?

[Scale-Master]

Not a problem. I have a 350 bored .040 over with a 400 crank in mine. 384.7 ci. Or 385. (.030 plus a 400 crank is a 383...) - Mark

[cooltc2004]

The correct equation, in case you were wondering is as follows:

Bore * Bore * Stroke * .785 * # of cylinders

I have no idea how 2PI fits in? Is that a standard for just V8's? Anyways, the above is the standard equation.

/edit: With that above equation, how do you calculate the Cubic Inches for a V6? Or what if you want to calculate the displacement for 1 cylinder? I dont think that equation is right, not at all, its even off by 2 tenths of a cubic inch for a V8.

[Mr. Luos]

The 2PI thing is basicly the .785*8.

If you want a quick calculator....
http://www.c5frc.com/calculators/Com...Calculator.htm

Just use half of the calculator. The bore and stroke to displacement part.

[cooltc2004]

Yeah, I figured it had to be something like that. Kind of dumb if you ask me, because you arent able to find the displacement per cylinder, for a different size engine, plus it was 2 tenths of a cubic inch off =P

[ct91rs]

Originally Posted by cooltc2004

Yeah, I figured it had to be something like that. Kind of dumb if you ask me, because you arent able to find the displacement per cylinder, for a different size engine, plus it was 2 tenths of a cubic inch off =P

That's the correct equation? Two tenths off, eh? I have no problem with being corrected, but it would be nice if you were right. Let's look at geometry:

Area of a cylinder: pi(r^2) x h, where r is the radius, and h is the height of the cylinder.

Now, bore = diameter, and stroke = height.

Half the diameter is the radius.

Bore is 4.04, so the radius is 2.02, and the stroke is 3.48

pi(2.02^2)(3.48) = 44.609962229....that is the displacement of one cylinder. Multiply by 8, 356.87969783....so we'll call it a 357.

Plug the numbers into the table on the link that Luos left, what do you get? The displacement is rounded to 356.88.

[cooltc2004]

Thats all well and good, but the equation you just gave me is not the same as the one you gave me the first time, you might get the same answer, but it doesnt follow the same logic.

The second equation might give you the answer, but your doing way more steps then you need to.

And theres no need to be a smart ass, because the equation that the makers of pistons and various internal engine parts gives you, is:

Bore * Bore * Stroke * .785 * # of cylinders.

Thats the standard equation.

[ct91rs]

Originally Posted by cooltc2004

Thats all well and good, but the equation you just gave me is not the same as the one you gave me the first time, you might get the same answer, but it doesnt follow the same logic.

Originally Posted by cooltc2004

I dont think that equation is right, not at all, its even off by 2 tenths of a cubic inch for a V8.

I tried to explain the geometry that allows one to determine engine displacement, and they do follow the same logic. You said my result was off, but in fact using either method I described you will get the same answer, the exact answer. But arguing this is a waste of time for us both, since we're dealing with differences of hundredths of an inch of total displacement, which is irrelavent to the topic at hand.

Originally Posted by cooltc2004

The second equation might give you the answer, but your doing way more steps then you need to.

That's why I provided a simplier equation to begin with.

Originally Posted by cooltc2004

And theres no need to be a smart ass.

I apologize for coming off that way.

Edit: Took out some unpleasantness.