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.

MP/Chapman Head Specifications
Stage VI 260Stage VI 285 MW
Part numberP4876383P4876386
Intake portProductionMax Wedge Large Port
Intake valve size2.200-inch2.250-inch
Exhaust valve size1.810-inch1.810-inch
Valve length5.400-inch (+.540)5.400-inch (+.540)
Intake port volume260cc285cc
Exhaust port volume84cc84cc
MP/Chapman Head Flow (Advertised)
Stage VI 260Stage VI 285 MW8
LiftIntakeExhaustIntakeExhaust
.100"71557755
.200"157112151112
.300"230177220177
.400"290211283211
.500"325233330233
.600"351242364242
.700"351252375252
.750"260381260
SOURCE
Barry Grant/ Demon Carburetion
Dahlonega
GA
7-06/-864-8544
barrygrant.com
Indy Cylinder Heads
8621 Southeastern Ave
Indianapolis
IN  46239
317-862-0224
Chapman Racing Heads
Woods Cross
UT
801-292-3909
www.chapmanracingheads.com
TTI Exhaust Systems
Corona
CA
9-51/-371-4878
ttiexhaust.com
Competition Cams
Memphis
TN
8-00/-999-0853
compcams.com
Westech Performance Group
11098 Venture Dr., Unit C
Mira Loma
CA  91752
9-09/-685-4767
www.westechperformance.com