Texas Flood wrote:
> Barkeeper - a round for the lot.....
>
> A friend of mine have a '91 fatboy with some Screaming Eagle pipes attached.
> He have asked me a couple of times what the pipe between the two main
> exhaustpipes is good for - he is thinking of building an exhaustsystem of
> his own (the poor bastard) !!
> Can't really see why when he has got them Screaming Eagles, but that's his
> business.
>
> Can someone please explain what this in-between pipe is for ?
>
> My theory is that it outbalances the resistanse of the two different lengths
> of the main exhaustpipes, so the resistanse is the same for both cylinders.
>
> TexasFlood
One theory is that every time one of the exhaust valve opens, the exhaust gases
have two
different paths and two mufflers to travel out of, resulting in less
backpressure and more
flow. Another theory is that a negative pressure pulse is created in the
crossover due to
an eductor effect as the exhaust it cruising by the joint, and this negative
pulse
travels up to the other exhaust port and helps start the exhaust flowing when
that valve opens.
Bottom line, a crossover will shift the torque curve to a lower RPM.
At least that much is proven.
HogDr
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