ACCEL HEI Super-Coils are a direct performance replacement for stock units. They feature highly specialized silicone-magnetic steel cores that, together with these coils' optimized winding resistance and turns ratios, deliver 10-15 percent more energy than Original Equipment Manufacturer coils. Specialized high-temperature epoxy resists shock and vibration and still increases thermal conductivity. Ideal for Chevrolet V6s and most Chevy V8s, ACCEL HEI Super Coils are compatible with both original HEI ignition systems and later model computer-controlled systems.