Of course, Freiburger recommends going right for the classic 6-71, which Weiand also produces. They're actually pretty reasonably priced, starting at just over $2,000 on summitracing.com for a kit with small-block manifold, the satin-finish blower, 2x4 carb adapter, pulleys, a Gilmer-style belt, tensioner, gaskets, and hardware. Don't expect it to fit under the hood, but according to Weiand, it should add 45 to 55 percent power.
Picking PistonsFrED Markus, Alexandria, VA: I'm getting ready to build an engine for my project car, a '73 Camaro. The engine won't be anything too spectacular, just a fairly sound 383 that will most likely use an aftermarket cast crank and 5.7-inch rods. I haven't decided if I'm going to run Vortec heads or go with aftermarket aluminum assemblies, but I'm hoping the budget is there for the aluminum, and I'm leaning toward Trick Flow 23-degree heads. If I do get aluminum heads, I'll shoot for 10.0:1 compression. My cam will be a flat-tappet hydraulic with about 0.525-inch lift and mid-230-degree range at 0.050. The car will be used for weekend fun on the street and occasionally at the track, and I'd like the car to have the capability of running 12s, though I realize it may take some nitrous to get there. That brings me to my main question: Do I need to run forged pistons, or will hypereutectics be acceptable? It seems like in the old days, all performance engines had forged pistons, but now that I'm shopping, most reasonably priced slugs are hypers, and most of these are marketed as high-performance pistons. I don't want to skimp, but I also don't want to spend money on pistons that could go toward my heads if hypereutectics can handle my needs. With eventual upgrades, I'd like this engine to approach 500 hp at the flywheel, or at least be strong enough to handle that level of power. I'm thinking of a 150hp shot of nitrous too. Will hypereutectic pistons disintegrate under these conditions?
Barry Rabotnick, Federal-Mogul Product Manager, Performance: You'd think a straightforward street/strip-style engine build would be easy, but this is actually the toughest application to pick a set of pistons for because many different choices will work. There's a lot of confusing information and marketing hype regarding the benefits of one material or design over another. Let's try to cut through the noise and make some clear decisions.
Pistons for automotive engines are manufactured using one of two methods: forging or casting. In addition, there are a couple of popular aluminum alloys for each method. Cast pistons for high-performance use are almost always made from hypereutectic alloy, which uses a high percentage of silicon (over 16 percent). Silicon in piston alloys improves wear resistance and adds strength at the cost of ductility (flexibility). Forged pistons are made from either 4032 alloy, which has about 11 percent silicon, or from 2618 alloy, which has greater high-temperature durability but essentially no silicon. For forged pistons, the 4032 is a better choice for long life in street and bracket cars; the 2618 is better for true race applications where long service life is less important than durability under extreme stress.