Beyond sliding the cylinder head into place, DiSomma torques all ARP fasteners to specification, lubing the threads with moly lube first. ARP supplied all the necessary fasteners for our project, which can be purchased separately or as a complete kit. We chose its stainless steel 12-point kit (PN 534-9501). Also shown is the CNC machined exhaust port of the AFR 227 head.
To keep our valvetrain intact and under control, we utilized Comp Cams shaft rocker system, 3/8-inch pushrods and solid roller lifters. It is very important to have the ultimate in valvetrain stability with the extreme cylinder pressures sustained from a blown mill. A flexing pushrod, unstable rocker or a cheaply engineered lifter can wreak havoc, causing well thought-out camshaft specifications to be way out of range, as well as causing potential damage. Be sure to choose you weapons carefully.
The Carb Shop was called upon to handle our blow-through carburetor duties. This is one area where a professional should be employed for this application. An amateur can perform modifications to retrofit their Holley carburetor for blower/turbo use, however with the anticipation of high boost levels-as well as protecting our investment-we'd just as soon stick with the professionals.
One lean exhaust reading at 20-30 psi of boost and kaboom!
The folks at Edelbrock were chosen for a suitable intake manifold. We picked the Super Victor (PN 2925) for its excellent flow properties and fuel distribution. The Super Victor is suitable for engines operating in the 3,500 to 8,000 rpm range, which fits right into our build.
Let's now follow along as Anthony DiSomma and the crew at M2 Race Systems complete our ProCharged 400 cid small-block.
Naturally Aspirated VS. ProCharged
With our ProCharger F-2 bolted on and ready to roll, John started the beast. After a warm-up and a few snaps of the throttle, our SBC mill sounded mean. After several partial pulls, multiple-timing adjustments and one jet change in the carb, we decided to let the mouse eat. By the time we hit 5,800 rpm, the engine started to break up a bit and John quickly backed her down. The dyno read 858.6 hp at 5,800 rpm with 21 psi of boost. While the air-fuel ratio was on the rich side (10.8:1) with VP Fuels C16 race gas and the timing was a conservative 31 degrees total, we needed to figure out what was wrong. We finally came to the conclusion that the valves were floating (being hung open) under high rpm boost conditions. With a seat pressure of 250 psi at the valve we needed to step up to at least 280-300.
In order to continue testing (in an effort to meet our story deadlines), we obtained a smaller crank pulley and larger blower pulley from ProCharger to produce less boost. After the pulley swap, we wound the mouse to 7,300 rpm and hit 15 psi of boost. The SuperFlow dyno read 973.6 hp and 722.7 lb-ft of torque-pretty good considering we are making half the boost we plan on making. It was also darn near netting a 90 percent power increase. We are also using a set of headers with a 1 3/4- to 1 7/8-inch step tube. Stepping up to a 2-inch or better will also net some serious horsepower gains. As we tried to push the engine further, we kept encountering our valve float issue, but don't fret-we'll get her fixed up in no time. Once proper seat pressure is achieved (either via a spring change or some shimming) we will most definitely conquer the 1,300hp barrier (hopefully with room to spare). We'll keep you posted, and don't forget to check out SuperChevy.com for video footage of our Hell-Raiser on the dyno.