Building a 572 Race Wedge Engine - 4.5 x 4.5 = 572

We've all heard the popular acronyms, "found on road dead" or "fix or repair daily" that we use to poke fun at fellow enthusiasts who chose to build brand-X iron. Here at Mopar Muscle though, we are firm believers in the adage that Mopar stands for massively over-powered and raced. And if the Ford or Chevy guys want to debate that saying we'll be happy to meet them at the track; we're there every weekend.

So when Rich Yates of Leesburg, Florida, approached us with a plan to build a 572ci race wedge for his '71 Duster, we were immediately interested. Even more exciting for us was the fact that Rich wanted to utilize some trick components, such as Jesel rocker arms and an adjustable Jesel beltdrive timing system. The engine will also be topped with a Hensley manufactured sheetmetal tunnel-ram intake with twin Dominator carburetors, so the potential for power really caught our attention. In fact, our only hesitation was the feeling we may be able to tweak more power from this engine than the Duster's back-halved chassis could take. But hey, too much power is a good thing, right? We can always make chassis improvements down the road if we need to, so we decided to build as much power as we could with this engine and leave the chassis adjustments for later.

Any time you're contemplating an engine build you need to clearly define your goals. Rich races his Duster in the Super-Pro bracket class every weekend, sometimes even twice in a weekend, so endurance is a key component to this build. Also, being the faster car in a bracket race not only provides the advantage of being the second car with the chance to red light (the first red light loses), but also ensures that once a slower car is caught at the top end of the track, you'll have the power to peddle the car and stay ahead of your opponent to win the race. For this reason, we want to build as much power as we can from this combination without sacrificing dependability. Rich's previous engine was a 540ci wedge that made close to 900 hp, so we figure the extra cubic inches and flow of the Indy 572-13 heads should easily get us into the mid- to upper-900hp range. With this kind of power and a ton of torque, the only problem we foresee is traction related. Our Duster has been back-halved to make room for 16-inch-wide slicks, and stiffened with a full cage and frame connectors, but traction still may be an issue for this combination. Our only saving grace is the adjustment capability offered by our four-link rear suspension, wheelie bar, and double adjustable front and rear shocks. On a marginal track we may still have problems hooking up, but hey, that's a byproduct of the power this 572 will be making, so in the name of low elapsed times, we'll deal with it.

The 572ci motor has become a staple for drag racers who utilize all brands of equipment, and Mopar is no exception. The 4.5-inch bore and 4.5-inch stroke make for a powerful and durable combination, which is ideal for a fast and consistent bracket car. Building a 572ci Mopar big-block, however, is not a task that can be accomplished with factory parts. None of Chrysler's production big-blocks have the bore spacing to accommodate the 4.5-inch bores necessary for this build nor will a factory block withstand the power that a 572 will make, so a Mopar Performance Siamese bore mega-block was chosen for this build. A Callies 4.5-inch stroke crankshaft will be used along with BME 7.125-inch aluminum connecting rods connected to Ross-forged, flat-top pistons. The deck height will be as close to the top of the cylinder as possible, netting a final compression ratio close to 14.07:1(see sidebar on calculating compression ratio). This engine will be spinning at upwards of 7,500 rpm so accurately balancing the rotating assembly is mandatory. Kevin Willis of Auto Performance Engines in Auburndale, Florida, handled the balancing job for us, as well as performing the remainder of the machine work for this project. Remember that accurate machining is key to the life of any high-performance engine, whether it is a street or strip engine. This combination utilizes some rather pricey parts, so we'll spend the extra money for an accurate balance job rather than risk destroying our high-dollar engine due to an imbalance issue.

While our parts were at Auto Performance Engines, we also had Kevin bore and hone our block with torque plates, as well as cut our new Indy heads for O-rings. If you're not familiar with sealing the combustion chambers utilizing the O-ring method, the concept is pretty easy to understand. A small groove is cut into both the block and the cylinder head around each combustion chamber where the head gasket seals. A piece of stainless steel aviation safety wire is then placed into one of the grooves (usually the one in the head) to form the O-ring. The other groove is called the receiver groove and gives the head gasket somewhere to go when the head is torqued onto the block. This method requires a copper head gasket and will virtually eliminate any leakage from the combustion chamber around the head gasket sealing surface. This method works exceptionally well in engines where cylinder pressures are much higher than normal, such as high-compression, nitrous-oxide, turbo, and supercharged applications. Our engine will be normally aspirated, but is relatively high compression so we'll see a benefit from the O-rings, but, more importantly, we will have the ability to add nitrous oxide at a later time without worrying about blowing a head gasket.