Can someone please explain to me, in as much detail as you have time for, what bore and stroke mean?? Thank You!

 

Simply put, "bore" is a measurement of how wide your pistons/cylinders are. When you hear of someone getting their engine "bored out" that means they enlarged the width of their cylinder by honing them out, and installing wider pistons.

"Stroke" is a measurement how far the piston travels up & down the cylinder. The stroke is affected by the length of the crankshaft throws. If someone says they "stroked" their engine that means they installed a crankshaft with a longer throw, and also would have installed shorter connecting rods.

Multiply bore and stroke together you can figure out the engine's displacement.

Hows that?

 

Not quite that simple. Its: Bore diameter x bore diameter x .7854 x stroke length x number of cylinders = displacement

 

i stroked my 302 to a 347...and used a longer rod

 

Yep, sometimes people have their engines stroked which is as previously described (throws being further away from the center of the crank).

Stoking
One benefit of stoking, adding stroke, to an engine is that you will get more torque. This is true because the pistons that push down on the connecting rods will have more leverage (as the throws are further away from the center fo the crank). The further out you go, the more you have to lower the redline because the greater force gets exerted on the connecting rods (in terms of cyntrifigul force).

Destroking
Sometimes people want a motor to be destroked. Reason for this is because the engine will be able to have a higher redline & will rev quicker. It is more stable at higher RPM's as well.

What is better?
Depends on what you are looking to do with the car, what kind of racing it will be for (auto-x, drag racing, track racing, etc), what characteristics you like in a motor, etcetcetc.

 

I think the formula is bore*bore*3.14*stroke*cylinders = displacement

if I'm wrong, please lemme know where .7854 comes from, cause either they didn't teach me that number or it's way too early at work...

 

EDIT: I was temporarily retarded.[8D]

radius ^ 2 * pi * height = volume of a cylinder

 

I know what you mean, I thought about that too. Its PI*r^2 * stroke for one cyl volume. They are just using total bore * total bore *.7854 * stroke to make it easier. It comes out the same, try it.

As for your math MikeHawke youre way off, you wrote the same formula twice in a row. 3.14 is PI, not a cc conversion factor. (bore/2)^2 * 3.14 * stroke is the volume of a cylinder, whether you use inches or cm will give you the answer, its not always cc and especially not the total cc.

 

I just realized that. me = DUMB. Sorry. I did that real quick on my way out for lunch. I'll fix it. Thanks man

 

i tell you its .. BORE X BORE X STROKE X 0.7854 X 8 = CU IN. O AND IM NEVER WRONG![&:] heres exp. 4.0 x 4.0 x 3.0 x 0.7854 x 8 =301.5936 just put your fuirges in my 408 is 4.030x4.030x4x0.7854x8=408.17928= 408 as for my big boy 4.530x4.530x4.5x0.7854x8=580.21612=580