Headers vs. Exhaust Manifolds ~ 'Let The Debate Begin'

I seem to remember the Magazines I read during the day,, said to expect 10 - 15%hp increase,, but I respect 69Cuda440 reference material.

This is the way I see it.. .

An exhaust manifold is about a 2 inch inside dia pipe, that has 4 entry doors in a row, leading to one exit door , of 2” dia.. at one end..

While running, the manifold is a high pressure area ,cuz when an ex valve opens, it is greeted by all the exhaust from other doors all trying to get out the small door at one end.. The exhaust trying to get to the exit, is blown backwards as another door between it and the exit opens,.. Also consider that the piston is forcing exhaust out as it comes up, but before the ex valve can close, another exhaust valve opens into manifold,, thus actually blowing exhaust (extinguisher) back into cylinder.. So the cylinder is still partially full of extinguisher, as the intake opens and takes a smaller charge of fuel, cuz cyl isn’t empty.. and mixture is contaminated, so less power… protract that,.. then consider..

While running, long tube header is low pressure, the exhaust valve opens and is greeted by an empty tube, that actually has vacuum created by the pulse of hot gas that’s halfway down a 3 ft. pipe,, aaaaAND that pulse of exhaust is being scavenged into the collector by the flow of gasses entering from the other pipes,,.. when the piston rises in the exhaust stroke, there is little resistance as the gases are sucked out, (more power) when the ex valve closes, the cylinder is nearly empty, with no loss of power forcing exhaust gasses into manifold,.. intake opens,, and full charge of uncontaminated fuel fills the cyl. (more power)

And I maintain long tube headers is the most cost effective way to gain horsepower..

jmo