How to Build New Hemi Performance on the Dyno. Richard Holdener

The torque curve tells the same story. The stock 5.7L Hemi simply couldn’t utilize the additional airflow. Since the stock 5.7L heads will support well more than 500 hp, they were more than enough for this stock truck engine. The head swap would be worth much more than 12 ft-lbs on the right application.

Test 2: Stock 5.7L vs TEA Heads on a Modified 5.7L Hemi

      Having just tested ported heads on a stock engine, we decided the extra airflow offered by the heads deserved a better test engine. Starting with a MP crate engine, the 5.7L was augmented with a camshaft that could better take advantage of the flow potential of the cylinder heads. The Comp 273H-14 cam profile offered a .547/.550 lift split, a 224/228-degree duration split and 114-degree LSA. According to the Comp catalog, this cam was designed with a broad operating range from 2,000 rpm to 6,200 rpm. But on our application, especially with the ported heads, the 5.7L pulled hard all the way out to 6,800 rpm. The remainder of the test engine included an MP single-plane intake, FAST injectors, and Accufab 4-hole throttle body. The single-plane intake was part of the reason the engine wanted to rev; the intake was designed to enhance high-RPM power production, but as we saw in chapter 1, not without a drop in low-speed torque.