Engine Size and Cubic inch

[knightjp]

I know this must be a stupid question, but me and my dad were talking about engine sizes and how its calculated... like for instance...
427 Ci - Does this mean the block size or the whole engine???

Another question is on litre...
I'm a little confused on this.... how is this calculated???
Is 5.3L the size of whole engine or the cylinders???? Someone told me its the cylinders...

[snshddog]

As the name Displacement describes, it is the difference in the size of the cylinder compaired from the piston at the top then the bottom of the cylinder. It is the difference across the entire engine. Liters is just the metric conversion of it.
In a nut shell, it is the size of the holes the pistons go in.

[knightjp]

Originally Posted by snshddog

As the name Displacement describes, it is the difference in the size of the cylinder compaired from the piston at the top then the bottom of the cylinder. It is the difference across the entire engine. Liters is just the metric conversion of it.
In a nut shell, it is the size of the holes the pistons go in.

So its not the size of the complete engine with headers, etc???

Let me get this right...
Is it the size of all the cylinders in the engine combined???

[jdmccright]

It is only the sum of the volumes of the cylinders within the block. All the rest just contributes to strength, cooling, etc.

1 liter (L) = ~61 cubic inches (cu in)

For a 427 CID (Cubic Inch Displacement) V8 engine, or 7.0 L, each piston would displace 427/8 = 53.38 cu in, or 7.0/8 = 0.875 L

[silicon212]

Cubic inch displacement:

Cylinder bore * bore * stroke * # cyl * 0.7854 = cubic inch displacement.

For example, a Chevy 350 engine, which has 8 cylinders, a 4" bore and a 3.48" stroke:

4 * 4 * 3.48 * 8 * 0.7854 = 350 (actually 349.858 rounded up).

The same formula works for determining metric sizes as well, just use the proper numbers.

[knightjp]

Ford displacing 589 cubic inches (4.627 bore x 4.375 stroke)
What is the size of this engine???

[jdmccright]

Use the conversion I gave earlier: 1 liter = 61 cubic inches (Hint: divide by 61 to get liters)

589 cubic inches IS the size of the engine that is referred to by manufacturers, gearheads, etc. External dimensions aren't used to identify engines.

[534BC]

This help? https://www.pamperedchef.com/orderin...=210&words=cup

Don't laugh.

[knightjp]

Originally Posted by 534BC

This help? https://www.pamperedchef.com/orderin...=210&words=cup

Don't laugh.

Ah yes... this was helpful...

[carbuzzard]

Basics: volume of a cylinder = (πrr)h. OK, this forum doesn't have mathematical notation, however, it comes out something like "pi times the radius squared times height."

Translate that into common engine terminology, well, pi is 3.1415...etc. It keeps going but that's enough. "r" or the radius is half the diameter, otherwise known as the bore. Height is the stroke.

So to find the volume (or displacement) of one cylinder, divide the bore in half and then multiply that by itself and then multiply that times 3.1415. Then then when you get that number, multiply it times the stroke.

Then to find the overall size of the engine, multiply that times the number of cylinders.



Of course, if you want to talk about the displacement of a rotary engine--like a Mazda RX-8's--you're on your own.

[knightjp]

Originally Posted by carbuzzard

Of course, if you want to talk about the displacement of a rotary engine--like a Mazda RX-8's--you're on your own.

Thanks for the info....
I wonder how they calculate the displacement in those rotary engines...

[curtis73]

Think of an engine's displacement (size) like a hypodermic needle. The plunger is the piston, the body is the cylinder, and the needle is the valve. As you draw the plunger back a certain distance, it sucks in a certain amount of heroin... I mean medicine.

Changing an engine's displacement means you either have a larger diameter syringe (piston and cylinder) or draw the plunger back farther (increase the stroke length.) So, an engine's total displacement is the volume of each "syringe" times however many cylinders there are.

In this way, one engine block can have many displacements. The small block chevy is a good example. Within one basic block, they made displacements from 265 cubic inches up to 400, and with aftermarket parts you can go as far as 450+ cubic inches.

[knightjp]

Originally Posted by curtis73

Within one basic block, they made displacements from 265 cubic inches up to 400, and with aftermarket parts you can go as far as 450+ cubic inches.

As far as what I've heard, the engine displacement comes from the size of the cylinders in the block. How is it that it can be increased by adding aftermarket parts???

[534BC]

Originally Posted by curtis73

Think of an engine's displacement (size) like a hypodermic needle. The plunger is the piston, the body is the cylinder, and the needle is the valve. As you draw the plunger back a certain distance, it sucks in a certain amount of heroin... I mean medicine.

That's almost as bad as my pampered chef measuring cup.

[534BC]

Originally Posted by knightjp

As far as what I've heard, the engine displacement comes from the size of the cylinders in the block. How is it that it can be increased by adding aftermarket parts???

Bore the cylinders out to make them larger diameter (with corresponding larger pistons)
Install a crank w/ longer throws making the length (stroke) longer.