Join Date: Dec 2005
Location: Michigan City and Bloomington, Indiana
Bike: 03 Silver R6
I can't help but partially disagree with the above statement, although it is a little old. First off, I'm relatively new to motorcycles but not even close to new with engines. The analogy to the hose shooting out water isn't the best for a couple reasons:
1-If you really want to use water as a comparison, then time it from when you turn the hose on with it empty until your jug is full with both, you'll notice that it in fact does take longer for the water to reach the end of the hose. The fact is, when you have the hose on full blast with a constant pressure, a constant amount of water will be exiting regardless; water cannot expand nor compress such as gases can. Once the pressure is established it will flow out of the hose at a constant rate as long as the loops in the pipe do not effect the diameter of it, so that much is correct. The fact is, with an exhaust system you do not have a constant flow; you have individual cylinders firing, meaning that, despite that they're firing VERY rapidly and may seem like it's a constant flow, it is not. Not to mention that gases do not flow like liquids anyway. Water and exhaust flow are like comparing apples and oranges.
2-Even when bends do not affect pipe radius, they still CAN cause a performance issue, albeit a small one in this case. But since we're talking technical terms, they do affect the performance. With a completely straight pipe, the exhaust is being shot out and, in a perfect world, is not hitting anything at all. (Read:no restrictions) The fact of the matter is that when you have a bend in the pipe, it is hitting the wall at an oblique angle. When the exhaust hits that wall, it causes a restriction, and herego a detraction from overall performance.
All in all, the short answer actually is YES. The bends can case a detraction in performance, although it may actually be a small one. I'm not just blowing smoke here; I'm a Physics major. I personally have performed experiments similar to this and found results accordingly. Sorry for the lengthy response, but I can't think of another way to say it in lesser words. Happy holidays to everyone