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On 2005-03-02 10:47, westmus wrote:
After Reading the intake manifold porting article from CarCraft nov 2000 (can be found here: http://www.jason.fletcher.net/tech/c.../ccnov2000.htm ). I was just thinking, what is limiting the intake flow, when ported like this, to be 210-220 cfm?

The article says that the Torker 289 ported can flow 260 cfm. But even full ported the ports are not as the big as the stock ports i the 351w heads.

So are the intake ports in the head big enough for even more flow, but bowl or shape are the limiting thing? Then there is no reason to spending time on gasket matching the intake ports, if there is no missalignment with the intake manifold, or is there?

I have a pair of C9 heads with 1.94/1.60, some rough porting done allready and I`m looking where to improve the porting allready done. My heads have a lot done in the exhausts but only a cleanup in the bowls on the intakes.

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I'd have to say that the intake outflows the heads because the intake runners are straighter than an intake port that has a big bend in it. Anything you can do to effectively straighten a port has a significant impact on flow. As far as port matching, if the manifold is larger than the intake port of the head in any dimension...top, bottom or sides...creating an exposed step, the incoming air is going to hit this obstruction causing turbulence. If the manifold were not creating this step(the same size as the head port or smaller), then the effect of port matching (as long as the manifold flows well) is minimized. In any case, I would always check how the ports are matching up and correct a obstruction if it exists.
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