Then, using a head like this with NO divider between the 2 center exhaust ports a fella ran a good test for our purposes.
In the fist test, the extractors funnel all 6 pipes into a single exhaust.
The second test the collector was cut off to create dual exhaust in 2 pairs of 3 into 1 systems.
In watching this keep in mind what we discussed earlier about those 2 center ports even with individual extractor pipes for the 2 center ports.
The first test produces a note like the typical sporty 6 cylinder exhaust note.
The second test, without change of cam, produces more of a rumble. Really wish he had rev'd it more.
So even though the exhaust dumps into the 2 center pipes through a siamesed center port arrangement through a gasket like this:
We can get variations in the exhaust note depending on how the exhaust is configured during the 2 tests.
Why?
In the first test, the sound waves of each pulse get re-combined into their natural 120* separation as they are funneled into the single pipe.
This is a similar sound effect as an X-pipe installed in an exhaust system for a 90* V8 with a 90* cross plane crank. The typical V8 which normally gives a rumble. Put the X-pipe in and the result is a symphony based on 90* pulse separation between left and right bank, fooling the ear into hearing what sounds like a 180* separation between each left bank pulse and each right bank pulse. A sound much like the earlier V8 example with 180* headers.
Think about that and any questions.
More later