Laminar Flow in XV Heads

It's going to be difficult to cover this topic without trying to teach (or refresh) the reader calculus and small-scale (molecular level) physics. Ideally in a conduit - like an intake boot - fluid flows smoothly in layers moving at different speeds which do not perturb each other. No mixing; no eddies; no turbulence. This is what we want up to the point where fuel enters the flow. Then we want turbulent flow. Tumbling; homogeneity. Up to a point. Smooth laminar flow is faster, we want to fill cylinders as quickly as possible. There is also a phenomenon called the Tau Factor (sometimes called "X") wherein droplets in suspension in a smoothly flowing medium have a tendency to draw out of suspension and wet the conduit walls. Polished walls almost guarantee this happening -- there is no roughness to disturb the smooth flow of the fluid; no turbulence.

The film beads up and starts to puddle on the port floor. It forms rivulets that flow down the port. The stream of raw fuel hits the back of the opening intake valve and is instantly vaporized. This causes a very rich area inside the cylinder. The tuner reads the plugs as burning rich and leans out the fuel delivery. The mixture becomes very lean except in the vacinity of the intake valve. The mixture reads rich, but the vehicle acts as though it is too lean. A compromise is reached, but the readings and the behavior do not match. The vehicle is impossible to tune properly and never runs to its potential.

More to come . . .

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