Stage VI Manifold Casting - Deep Breathers

Next up, we had the 285cc Chapman Stage VIs. We set the bar pretty high with our baseline head, a combination we already knew worked. The large-port Chapman heads required a Max Wedge intake. We utilized a Max Wedge sized low-deck unit from Indy, which we matched to the heads with adapter plates. An RB intake would have been a direct bolt-on, however, we didn't have a MW-port RB intake on hand for the test. As with the iron heads, the intake was mated to the large King Demon's pattern with an adapter spacer. Other than the heads and intake, the combination was identical. What were the Chapman's worth? Our 470 cranked to the tune of 774 hp at 6,700 rpm, and 667 lb-ft of torque at 5,900 rpm. No, we didn't sneak on a supercharger or nitrous. The Chapman heads just cooked the books on anything we'd seen from an engine of this type, shattering the power level of our monster iron heads by 132 hp and 56 lb-ft of torque. Are they really that good? We used these heads in this same combo in a national engine-building competition, taking on some of the biggest names in the business. Our 470 out-horsepowered every competitor in the game, be it Ford, Chevy, or Mopar, including Hemis. Yeah, the Chapman's deliver the goods.