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#### Deadtoday

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I copy/pasted this from another website on how things work to give a more technical viewpoint of what constitutes engine displacement.Deadtoday said:

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What is displacement?

Displacement is the volume of air "displaced" by the pistons during a single engine cycle. In terms of a single cylinder, displacement is the volume of the space traveled by the piston. The two factors that make up engine displacement are bore and stroke.

To calculate the displacement of an engine, first calculate the displacement of a single cylinder. The formula for the volume of a cylinder:

V = hr2

where h is the height of the cylinder and r is the radius of the cylinder (halfway across). If given the bore (diameter), multiplying it by ½ (dividing by 2) will yield r. h is expressed as stroke thereby giving the formula for engine displacement:

Displacement = Stroke * * (Bore / 2)2 * [# of cylinders]

Note that when Stroke and Bore are expressed in inches, displacement is solved in units of cubic in (ci). If Stroke and Bore are expressed in mm, then calculated displacement (in cubic mm) must be divided by 1000 to be expressed in cubic cm (cc), which is the same as milliliters (ml). Also note that engine displacement is normally expressed in liters (l) by dividing the displacement in cc once again by 1000.

For Subaru's 2.5L H4 released in the U.S. 2000 models, the Bore is 3.92" and the Stroke is 3.11". Therefore:

Displacement = 3.11 * * (3.92 / 2)2 * 4

Keep in mind that the Bore and Stroke numbers are not exact. They are rounded, so the calculated displacement will not be exact. In this case, displacement is calculated as 150.14 ci., but the published displacement is actually 2458 cc (2.5 l), or 149.996 ci.

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A few other tidbitds to ponder...Deadtoday said:

A larger displacement typically makes more torque, but overall horsepower/torque depends on the rest of the components and controls that are placed into the motor.

The 5.2L/318ci, 5.9L/360ci, and 6.7L/408ci Magnum motors all share the same blocks, the primary difference between these motors is the length of the stroke. The 408ci configuration makes significantly more torque than a base 318ci motor.

J

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You can it to either engine. If you bore the 318 .030 over and put a 4" crank in it it will yield you a 390 c.i. stroker. Now do the same thing to a 360 and it will yield you a 408 stroker. If you want the larger cubic inches i would go with a 360 and do the stroker. Money wise it depends on what you do. If you do the work to your own 318 then it will be cheaper but if you get a new block then your gonna pay more. The parts will be the same except for the pistons and maybe the cam depending on what you want to go with. Its just some research you need to do and call some guys to see what they can do for you. I am having one build by John Mercedes as we speak and i paid 7500 for my 408 stroker with a new block, crank, pistons, connecting rods, and head work and assembly.Jason said:

SinCity R/T said:I copy/pasted this from another website on how things work to give a more technical viewpoint of what constitutes engine displacement.

--------------

What is displacement?

Displacement is the volume of air "displaced" by the pistons during a single engine cycle. In terms of a single cylinder, displacement is the volume of the space traveled by the piston. The two factors that make up engine displacement are bore and stroke.

To calculate the displacement of an engine, first calculate the displacement of a single cylinder. The formula for the volume of a cylinder:

V = hr2

where h is the height of the cylinder and r is the radius of the cylinder (halfway across). If given the bore (diameter), multiplying it by ½ (dividing by 2) will yield r. h is expressed as stroke thereby giving the formula for engine displacement:

Displacement = Stroke * * (Bore / 2)2 * [# of cylinders]

Note that when Stroke and Bore are expressed in inches, displacement is solved in units of cubic in (ci). If Stroke and Bore are expressed in mm, then calculated displacement (in cubic mm) must be divided by 1000 to be expressed in cubic cm (cc), which is the same as milliliters (ml). Also note that engine displacement is normally expressed in liters (l) by dividing the displacement in cc once again by 1000.

For Subaru's 2.5L H4 released in the U.S. 2000 models, the Bore is 3.92" and the Stroke is 3.11". Therefore:

Displacement = 3.11 * * (3.92 / 2)2 * 4

Keep in mind that the Bore and Stroke numbers are not exact. They are rounded, so the calculated displacement will not be exact. In this case, displacement is calculated as 150.14 ci., but the published displacement is actually 2458 cc (2.5 l), or 149.996 ci.

here is a easier formula...

(bore)2 X stroke X # cyls X .7854 = displacement

thus (3.06)2 X 6.123 X 8 X .7854 = 360.2

the one above(Steves) is to calculate liters to cubic inches...

J

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Thanks wykdrt, that's pretty much what I wanted to know.

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wykdrt said:. I am having one build by John Mercedes as we speak and i paid 7500 for my 408 stroker with a new block, crank, pistons, connecting rods, and head work and assembly.

John does a great job!!! He really knows the ins-and outs of these motors :mullet:

Oh I don't have a 408 but I have a friend thats having one built and the pics look awesome!!!

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