Related Photo Galleries
'97 4.6L Two-Valve W/Zex Nitrous
It should be obvious from the supplied graphs that the stock 4.6L responded very well to CNC-ported heads, the Comp cams, and PI induction system. The ported PI heads not only improved airflow, but the static compression as well, thanks to a reduction in combustion chamber volume (the PI heads have smaller chambers that the non-PI versions). The Comp XE274H cams stepped up the cam timing significantly (0.500 lift and 236/240 duration at 0.050), while the late-model PI intake (with AccuFab 75mm throttle body) offered a substantial flow increase. The combination upped the power output of the early 4.6L Two-Valve from 266 hp and 341 lb-ft of torque to 390 hp and 384 lb-ft of torque. Torque production from the modified motor exceeded 350 lb-ft from 3,800 rpm to 5,800 rpm.