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Cross over pipe

As far as I can tell, it is to increase overall exhaust flow velocity, improving the scavenging (emptying) of the contents of each cylinder during its exhaust stroke, with the inertia of exhaust gasses from one cylinder being able to draw/suck on the other cyclinder's exhaust port, helping it empty more quickly and completely.

Enjoy,
Rich P
 
RibEye said:
As far as I can tell, it is to increase overall exhaust flow velocity, improving the scavenging (emptying) of the contents of each cylinder during its exhaust stroke, with the inertia of exhaust gasses from one cylinder being able to draw/suck on the other cyclinder's exhaust port, helping it empty more quickly and completely.

Enjoy,
Rich P
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It sounds right, except that you can not draw exhaust from the other cylinder on it's compression stroke. It was my understanding that the crossover allowed pressure wave build up, a low pressure escape path to flow into, allowing for better flow over all and better cylinder scavenge. The MoCo may test the exhaust for the location of pressure points in determining where the co pipe should go.
 
If you are really interested check out RB racing's website. They go into great detail to explain this. Sounds pretty intense the lengths they go through to figure it all out.
 
smitty901 said:
It is called scavenging. For an HD it is as close to best of both worlds as you can get.
HD big Vtwin produces better low end torque with a 2 to 1 exhaust system. But a free flowing system produces more power on a flat out wide up top end run.
The HD system allows the exhaust to act a lot like a 2 to 1.
Start your ride up walk around back places hands near exhaust feel the difference. The system also allows of easier tuning.
Click to expand...

I just went from tru-duals back to a stock header. I was looking for more torque. (went with Jack Pot Dyno Tuned mufflers) Seems to have helped.
 
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