Bored & Stroked
 

What do these terms mean? i have heard of an engine being bored .0400 over or a "bored out v-8". But what does it mean? Also, what does it mean if it is a Stroked 302 or a stroker kit??? thanx for the help

Boring the motor is just like it sounds. It bores out the sides of the cylinder walls to make them bigger. Stroking it is just changing the stroke that the crank is making.

What does the CI mean in your engine? cool indeed? just wondering

347 cubic inches..

I bored my motor out .30 over and stroked it out to a 347...

Smokedawg's 347 cu. in. motor would have been only 342 if he had not bored the cylinders to .030" over.

Likewise, my 331 cu. in. motor would have been only 327 had I not had mine bored .030" over.

Obviously, in both cases, we had to get pistons that measure 4.030" to fit properly.

The more you overbore the cylinders, the more displacement you get, however there is a point of diminishing returns when you bore too much and therefore loose strength in the cylinder/block walls.

E

ok, so if u have a 327ci engine bored .030 over it makes it a 331 and not a 330? do u not take the extra 3 from the .030 and add that to the ci of the engine like...
327ci+.030ci=330? why 331?

because when you bore it out .030 over, you make the entire bore slightly bigger in diameter. Basically, with a 302, if you filled the cylinders up with water, then measured the amount it took to fill all 8 of them, you'd have 302 cubic inches of water. When you take .030 off the cylinder walls, then measure it again, it turns out to be 306 cubic inches. Does this make sence?

To figure an engine's displacement, the formula is:

pi / 4 x bore squared x stroke x # of cylinders

Now, pi (3.1415927) divided by 4 equals .7853982, so the first part of the formula will always be .7853982:

.7853982 x bore squared x stroke x # of cylinders

Now, a 302 has a 4" bore, a 3" stroke, and 8 cylinders, so, by substituting those numbers, you get:

.7853982 x 4 squared (16) x 3 x 8 or:

.7853982 x 16 x 3 x 8 = 301.5929 cubic inches

With me so far?

Okay, now let's say you bore the engine .030" over, which means increasing the bore diameter of each cylinder to 4.030". Then the formula would look like this:

.7853982 x 16.2409 x 3 x 8 = 306.13375 cubic inches.

If you were to bore it .060" over, the formula would become:

.7853982 x 16.4836 x 3 x 8 = 310.70853 cubic inches

Get it?

Take care,
-Chris

By the way, to help put it into perspective for you, .030" is approximately as thick as 10 sheets of notebook paper.

Take care,
-Chris

simple yet effective.

props for the 100% correct answer

is there anything u dont know?

lol

peace