Quote:
Originally Posted by 911monty
While you ultimately wanted to reduce back pressure by using the 2 X 2.5" adapter that actually will increase pressure. Expanding the diameter reduces velocity of the gas, reduce velocity increase pressure. Just my .02.
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No way dude, I used a level 5 hex to actually cause the gravitational pull of the crankshaft to accelerate flow at the level of the expansion...
Joking aside, I'm not sure I follow you there. Bernoulli's principle certainly dictates pressure inversely proportional to flow velocity over a surface, but that is not the same as pressure within a cylinder. I don't disagree with the fact that this will slow gas velocity at the expansion, and a decrease in flow velocity will certainly change flow dynamics, especially at the boundary layer (between turbulent and laminar flow). But, minimizing heat loss through the system (hence the wrap) should mitigate this and maintain the desired pressure gradient per the ideal gas law (PV= nrt, keep the nrt equal and P and V move in opposite directions) and Pousielle's law (restriction of flow through a tube is inversely proportional to the the 4th power of radius)
If your statement is correct - i.e. change in pressure is directly proportional to the cross sectional area of flow, this would mean that an infinitely large expansion (i.e. from an exhaust tube to the atmosphere) would create an area of infinitely large pressure. If that were the case, then I think we just turned our exhaust pipe into a rocket booster?!?
That is, unless I have completely misunderstood what you were getting at.