The best cylinder head will also benefit from a properly matched intake manifold. The rules dictate a cast-aluminum single-plane intake. It may be worthwhile to actually flow the intake manifold with the head to see which works best. You can angle-mill the heads to increase compression, but that will also require milling the intake to match. Working with a company that offers both heads and intakes, such as Edelbrock, Dart, or Brodix, may be beneficial. Look for an intake that has a generous radius directly underneath the carburetor mounting pad. This is important to enhance power and improved mixture distribution. Look carefully at the position of the port relative to the heads on both sides of the engine. Often a core shift will make one side fit better than the other side. This is important since the manifold cannot be ported or massaged. Carburetor height is limited to a 2-inch spacer; this might be an advantage, but be careful. Often a spacer will improve top-end power at the cost of midrange torque. When you add nitrous, especially at the launch, this really pumps the torque, so a small torque loss with the taller spacer may work out.
The claim rules exempt nitrous, so you could spend some money on a well-engineered nitrous system that works with your package. While the nitrous jet is limited to 0.63 inch, the way the nitrous and fuel are introduced into the manifold can have a big effect on power. The more evenly the fuel mixes with the nitrous, the less fuel you need, which can make a little more power. Be very careful here, because too lean a mixture will kill pistons in the blink of an eye. It happens all the time. Other nitrous tricks include running a full bottle with each pass to maintain system pressure throughout the run. Keep the nitrous pressures between 950 and 1,000 psi.
Cam TimingWe've left the voodoo subject for last. The rules state you must use a flat-tappet hydraulic or mechanical-lifter camshaft, and you can't run more than a 0.485-inch valve lift. We're assuming these engines will make peak power around 7,000 rpm, so this means you're limited to a camshaft lobe lift of no more than 0.323 inch for a 1.5:1 stock Chevy rocker ratio and 0.303 inch for a Ford with a 1.6:1 rocker. Assuming this higher engine speed for peak horsepower, our cam grinder and engine-builder sources like Joe Sherman and others suggest durations of between 250 and 270 degrees at 0.050-inch tappet lift for the intake side with 10 to 14 degrees more on the exhaust side to compensate for the nitrous. Lobe separation angles no tighter than 108 to 110 degrees and perhaps wider would be a good idea. Tighter lobe separation angles tend to make the engine peaky, while wider lobe separation angles produce a broader powerband that is usually beneficial.
Both Comp Cams and Crane offer specialty lobes in their master cam-lobe profile books that will produce lifts in the 0.485-inch range with durations at 0.050 from 240 degrees up through over 270 degrees of duration at 0.050. This is probably the area where you will do the most experimentation, since each engine combination (based on the cylinder head and induction flow) will desire very specific cam timing requirements.
Power to RunThe bottom line is that it's going to take 700 to 750 hp and a strong torque curve to run 10-flat or high 9s in decent air, along with an excellent chassis and suspension system to hook all this power to the ground. Low 10s and high 9s are a great ride in any car. If this sounds like fun, think about what it would take to build a Cheap Street car you could take to the track. If enough readers e-mail us with requests, we could probably be coerced into building a Cheap Street small-block to test some of these theories. It might be fun.