In part 2 of this series, we analyzed the bottom end of the LS7, but it's the cylinder heads that form the heart of any naturally aspirated engine as an engine's power at any point in the rev range is quite simply a matter of airflow. Simply increasing the displacement without a corresponding increase in cylinder head flow will result in moving the powerband lower in the rev range, but won't significantly increase average or peak power. Utilizing that big-displacement and rev-tolerant bottom end took the most serious set of heads ever utilized by a small-block Chevy V8, and one of the best set of heads ever bolted on a production engine.
Where as other GenIII/IV GM V8s use a tall and extremely narrow ?cathedral?-style intake port that yields good velocity and swirl characteristics, the LS7 essentially uses the same large rectangular intake port that is used for the SB2 NASCAR engine, and yields similar flow numbers - a whopping 360 CFM (approximately 35% better than GM?s much-praised ?906 Vortec head). Offset intake rockers are used to provide more port cross-sectional area at the pushrod ?pinch point?, and the ports and chambers are finished using a 5-axis CNC machining process. The use of titanium is carried over to the 2.2? intake valves, and the 1.81? exhaust valves are sodium-filled stainless steel. Valvesprings are of the ?beehive type?, which decrease mass not only through their shape but also by allowing smaller-diameter retainers. They also help decrease harmful valvetrain harmonics.