Never have quite understood that...I'm assuming it means that each cylinder has been bored .30 inches greater in diameter...
or .30 centimeters?

 

It means that the cylindar has been bored 0.030 or 0.060 over size in inches. If you look at a foreign car the over size measurements are in mm and are smaller.

 

Talisker,

So how would I compute the total new displacement if I had, say, a 460 that was bored over .060?

J

 

Take the actual ID, calculate the area of that diameter, and multiply by the actual stroke, multiply that by 8 all in the same units.

 

OK, so I'm adding .060 inches to whatever the diameter is?

 

Yup.

The volume for a cylinder formula is V=pi*D*D*H/4 , multiply by 8 for a V8 engine.

D is the cylinder bore diameter
H is the stroke (height of the cylinder)
pi=3.14159 (close enough)


hope that makes sense. It's not exactly easy to write forumlas on a PC.

 

It is always better to actually check the bore rather than assume that it is the "book" value + the overbore. On the other hand the book value + the over bore can't be too far off.

I am glad that there is someone else that only remembers pi to 3.14159.(good enogh for govenment work)

 

¶ r 2 h .........

is the correct formula...or...3.14 x R x R x H....Radius..not diameter...right?

 

radius is half the diameter...

d/2, hence the 4 in the denominator.

 

gotcha....

 

I do <b>Bore x Bore x Stroke x .7854 x # of cylinders</b>. The .7854 is Pi divided by 4 (or thereabouts).

 

wanna get real fancy? (or really, really lazy)

a 460 starts with 4.32" bore, and 3.85" stroke.

http://raceabilene.com/kelly/hotrod/compression.html

 

GO: Pi (bore)Radius, Squared Height(stroke)
3.14159 X (2.180x2.180) X 3.850 = 57.4808554166 X 8cyl. =459.85cu in
------------------------------------------------------------------------------------ add .060" bore(4.420") makes the radius 2.210" squared =4.8841x3.14159x3.85=59.07378x8cyl=472.6 cu inches
------------------------------------------------------------------------------------
472.60
-459.85
-----------
12.75 cubic inch increase in displacement
This would make this big block a real contender in any circle!
Huffer

 

If you don't want to mess with pi, but still want accuracy (eg if you have a calulator that doesn't have pi), just use 22/7.