Originally Posted by antarius

Here's a quick diagram I threw together of another engine not mentioned, compared to the more common I4 and V6. The VR6 is the one I'm talking about (yes, because I'm a VR6 Volkswagen whore).

Generally, the "straighter" up and down the cylinder the more torque it makes, however; the engine is usually longer horizontally in that case. A V formation is generally considered a good combination of both being relatively compact and still making a good amount of torque. A large 8 cylinder engine would have to have an insanely long engine bay to house an Inline-8, but it needs a much smaller one for a V-8, make sense?

Well, Volkswagen went and squished the idea's of an I4 and a V-6 together and came up with a VR6, what you see is an engine with about 1/3rd more "thickness" than a typical I-4, which only has one row of cylinders, and it's roughly the same length horizontally as well. Compared to the V-6 shown on the bottom, you can see the space it saves.

I'm not saying what's better, but there's some more things out there for ya to look at...

Originally Posted by Kestrel

It's a vibration thing. If you fire 1,3 and 2,4 the engine will want to rotate as the pistons move up and down, whereas if you fire 1,4 and 2,3 the engine is balanced symmetrically.