These extreme loads on the end of the crankshaft also place severe bending loads on mounting brackets. The beauty of a centrifugal is that if you are a talented fabricator, it's possible to build your own centrifugal supercharger mount, but be sure to reinforce the bracket. A single 31/44-inch-thick aluminum plate will probably not work. Several systems now employ dual 31/44-inch-thick plates in an effort to prevent the blower mount from flexing. This adds weight and complexity but does wonders for keeping the belt in place on the pulleys.
977HP Street 540 RatWe crammed everything we learned in this blow-through story into a 9.5:1, 540ci big-block Chevy using an ATI ProCharger F-2 centrifugal to see what kind of power we could make. The basic short-block has not changed since we used it to test Edelbrock heads back in February '05 ("Super-Sized Rat"), making 711 hp normally aspirated. Because we knew this would be an expensive package, we kept the price down by opting for a set of factory iron rectangle-port heads and changed the cam.
For the intake side, we went with a Dart single-plane intake and a 750-cfm Quick Fuel Technologies 4150-style carburetor. We also selected a Comp Cams Xtreme Marine hydraulic roller with 250/254 degrees at 0.050-inch tappet lift with 0.575-inch lift and 112-degree lobe separation angle using 1.7:1 Comp roller rockers. On top, we also added a pair of Billet Fabrication aluminum valve covers and TD Performance breathers. ProCharger supplied the blower-drive system, to which we added an Edelbrock aluminum water pump and March pulleys, plus a mount kit for the Bosch alternator. Rounding out the package is a set of 2.125-inch Hedman coated headers.
Dyno DayTest 1 was our normally aspirated baseline run on 91-octane pump gas with a Quick Fuel 850-cfm carburetor. This 9.5:1 Rat is no slouch, making 620 lb-ft at 4,800 and 623 hp at 6,000.
Test 2 began with a 50/50 load of 91-octane pump gas and VP C-16 race gas for roughly a 104-octane brew. At a maximum of only 11.75 psi boost pressure, the motor made 940 lb-ft of torque at 5,200 and 977 hp at 5,700 rpm. There's much more power left in the blower-a 540 with good heads can make 1,200 hp.