STOP Using the 7 Degree Rule! Intake Runner Taper Done RIGHT

The 7-degree intake runner taper rule has been repeated for decades, but it's fundamentally flawed. In this video, I explain why fixed angle rules don't work and show you the correct way to design intake runners based on port velocity and energy. WHAT WE COVER: Where the 7 degree rule came from - divergent vs convergent confusion. Why diffuser angles are velocity-dependent not fixed numbers. Land speed vehicles at 600mph prove the point - nearly FLAT diffusers. Convergence rules: 2-4 degrees Larry Atherton, 3.5 degrees common, 4 degrees Chrysler. Divergence rules: 5 degrees David Vizard actual testing vs 7 degrees academic theory. Why I don't use angles - I design to CSA and target air velocity. Live demonstration of Einstein Motors Runner Calculator. THE REAL APPROACH: Instead of blindly following angle rules calculate target air velocity at the valve, port CSA at cylinder head, required CSA at plenum entry. The angle is just whatever geometry connects them over your runner length. KEY INSIGHT: If your port is oversized less taper needed. If your port is tight more taper acceptable. The angle is a CONSEQUENCE of the flow physics not a design input. Einstein Motors: https://einsteinmotors.com.au Bain Racing: [email protected]