Single vs. Dual Plane (347 Ford)
Looking at the XFI cam specs on our 347, we couldn't help wonder if the combination might benefit from a single-plane intake. We knew there would be a sacrifice in low-speed torque for the gains at the top end, but we were still curious to see just how much power the combination had to offer with the right intake manifold. Replacing the dual-plane intake with a funnel-web resulted in the typical single-plane, dual-plane test results. The dual-plane intake offered better power up to 4,800 rpm, but the FunnelWeb pulled away thereafter. Equipped with the FunnelWeb, the 347 produced 500 hp at 6,600 rpm and 441 lb-ft of torque at 5,300 rpm. Geared more for top end, torque production with the FunnelWeb exceeded 400 lb-ft from 4,000 rpm to 6,500 rpm.