The '07 Amsoil/Mopar Muscle Engine Challenge - Tech

We all know that an engine dyno can be a useful tool for finding horsepower while tuning a performance engine. Let's face it though, engines don't propel dynos, they propel cars. Since the rules of our Engine Challenge require a minimum of three qualifying pulls through the full 3,000- to 7,000-rpm range, followed by a minimum of three judged pulls, we ensure the contest engines aren't just dyno mules built only to last a couple of pulls, but real engines that can survive the abuses of cruising around town, highway driving, and making passes at the dragstrip. Because we also wanted to make certain the engines in our challenge are typical of engines our readers can afford to run in their cars, we factor the cost of the parts that went into the engine into the power the engine produces for a power-per-dollar rating.

This year, our Engine Challenge featured the small-block Mopar powerplant and displacement was limited to 410 ci. We were certainly impressed by the diversity of these potent small-blocks, and even more impressed by the power they made running on 93-octane Rockett Brand pump gas. These engines proved to be durable, powerful, and economically built, epitomizing the intent of our competition.

This month, we'll take a look at the first place engine of Indy Cylinder Head and the second place engine of Schurbon Engine and machine to see what parts and techniques each of these builders utilized to finish well.

Indy Cylinder Head
Indianapolis, Indiana
It takes power, durability, and a cost-effective combination to be competitive in our Engine Challenge, and Indy Cylinder Head had just the right mixture of the three to score a win this year. Though better known for their high-flowing, aluminum cylinder heads and big, cubic-inch race and street engines, engine builder Ken Lazzeri stated that the way our contest rules factor costs, building an economically priced, cast-iron-headed engine just made more sense than going for all-out power. Earning a win in this year's challenge proved his theory right-the Indy entry made just enough power to finish decimals ahead of the second place engine.

While externally, the Indy entry looked just like any other Magnum-headed small-block, internally these guys pulled out all the stops. A factory 360 block was bored .030-inch oversize, and then filled with an Eagle cast crankshaft, Eagle I-beam connecting rods, and Wiseco Pro True flat-top pistons for a displacement of 408 ci. A factory Mopar oil pan was utilized in conjunction with a Milodon windage tray and Sealed Power oil pump to ensure everything stayed lubricated during the dyno pulls. The parts they selected worked well as the engine performed flawlessly while on the dyno, and the bearings looked like new after multiple pulls to 7,000 rpm.

Atop their engine's solid bottom end, Indy resisted the urge to utilize a set of their aluminum race heads, using Magnum R/T cast-iron cylinder heads instead. Stating that the Magnum head is hard to beat for the cost, these heads were treated to some very cool in-house tricks, which greatly added to the power this engine produced. To keep the valvetrain light, hollow/sodium-filled intake and exhaust valves from the new-generation Hemi engine were utilized. Since these valves have a shorter stem length than factory Magnum head valves, the crew at Indy actually remachined the combustion chamber of the head so the valves would work. Since they were machining the combustion chamber anyway, they CNC machined the head's combustion chambers to the chamber found on their popular 572-13 cylinder head. Knowing our rules prohibited welding or epoxy modifying the cylinder head, they machined the pushrod "pinch" area of the port to a larger size, and then pressed in a brass sleeve to seal the pushrod area and increase the width of the intake port for improved flow. Hand porting was then performed in-house to optimize the flow characteristics of the cylinder heads.