Help me out bros, I've got a theoretical problem for you and the numbers a text book is showing are way off from what my friends and I are getting.

I have a 9 cylinder engine with a bore of 5.5" and a stroke of 6". What is the total piston displacement?


In the book it says the following:
Area = 0.7854 x bore squared
Volume = piston area x stroke
Piston displacement = volume x no. of cylinders

What does 0.7854 represent?

In the textbook I'm getting 1282.95 as the answer, on paper we are getting 1060ish. What am I missing? It's got to be obvious

The .7854 is just pi/4. The book is right but I prefer to just do the below:

V = pi(r)^2*h

V = pi*2.75^2*6 = 142.55

142.55 * 9 = 1282.95 in3

Thanks for helping me understand that, math has never been my strong suit

U don't need rocket scientist to figure this out. Go to GD