Just thinking out loud

Spud

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Looking at a pic of the water cooled GS. I suddenly wondered why the exhausts don't exit vertically downwards and then a smooth curve out of the back?

I thought it was all about smooth gas flow and getting rid of exhaust gases ?

Or, does there need to be certain length of pipe to get the best performance or create enough back pressure in the system or something?

Any experts enlighten me?
 
It always comes down to length giving the best performance��
 
.... and if they exited straight down and back, you wouldn't see them :eek:

It wouldn't look right, a motorbike without an exhaust :rob

:beerjug:
 
its all black magic to me :D but i still think the longer radii on the Mivv headers look like they provide better flow than the standard shape. But then again, Akrapovic (and remus) use that shape....




 
Spud said:
Looking at a pic of the water cooled GS. I suddenly wondered why the exhausts don't exit vertically downwards and then a smooth curve out of the back?

I thought it was all about smooth gas flow and getting rid of exhaust gases ?

Or, does there need to be certain length of pipe to get the best performance or create enough back pressure in the system or something?

Any experts enlighten me?
Click to expand...

The exhaust leaves the engine in pulses, behind each pulse is a negative pressure, the idea is to have that negative hang close to the opening inlet valve to pull the next charge in.
Don't think of it as flowing water.
 
duckspeed said:
The exhaust leaves the engine in pulses, behind each pulse is a negative pressure, the idea is to have that negative hang close to the opening inlet valve to pull the next charge in.
Don't think of it as flowing water.
Click to expand...

I can see that, but, if the inlet is opening, is the exhaust valve not closed ? Or do they overlap a little ?
 
duckspeed said:
The exhaust leaves the engine in pulses, behind each pulse is a negative pressure, the idea is to have that negative hang close to the opening inlet valve to pull the next charge in.
Don't think of it as flowing water.
Click to expand...

And it all happens at the speed of sound. If you watch the moto 3 races in the wet. The slow mo hd shots of the rear of those little bikes you can see the pulses exit the exhaust.
 
I've read that another factor was the esthetics. BMW wanted to maintain a semblance of their trademark exhaust forward look that has been there since 1923.
 
Nippy Normans supply Touratech, Wunderlich, Desert Fox and many other makes of accessories.
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