Manifold flow

Discussion on general flowbench design

Postby 2seater » Sat Jan 20, 2007 12:12 am

Rather than drag up several pages of suggestions and replys from Oct. of last year, I am just posting the results of testing the intake as suggested, one port at a time. This is a completely stock typical fwd manifold with a plenum closely matching the engine displacement of 231 ci., not a TPI style with long runners. I tested at four points, 14", 28", 42" and 56" wc. depression, actually pressure, since this is blow through from the throttle body. I noted no tendency for the flow to nose over at the flow rates I could generate. Laid out on a graph, the flow goes up in an almost straight line for every port. At every test point the lowest flow was between 93% and 96% of the highest. The flow averaged 123 cfm @ 14" and 246 cfm @ 56", four times the pressure to double the flow. The numbers are pretty low when compared to a high performance head flow, showing an average of 175 cfm @ 28" from the bare manifold port. Two ports are consistantly lower than the others, the closest to the inlet being the worst, as expected, but the middle one on the same side was only a little better, which was a surprise. All of the others closely matched with the graph lines actually crossing on a couple of them. All in all, using this test regime, the manifold works much better than I expected, and I want to thank all of the contributors for the previous input.
2seater
 
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