2009 Amsoil Mopar Muscle Engine Challenge Sponsors

2009 Amsoil/Mopar Muscle Engine Challenge LaRoy Engines & ProMax Performance

The 2009 Amsoil/Mopar Muscle Engine Challenge

From the May, 2010 issue of Mopar Muscle

By Dave Young

Photography by Dave Young, Randy Bolig

As the 2009 Amsoil/Mopar Muscle Engine Challenge has proven, it's difficult to beat the low-deck stroker, and more specifically the Chrysler 400 block with a factory 440 crank, when it comes to power per dollar. All of this year's competitors were required to build a low-deck big-block for our annual contest, and all of the engine builders chose a factory 400 block for its large bore size. Builders were also required to run Edelbrock's Performer RPM cylinder heads, but could port and otherwise modify the heads pretty much any way they chose. All of the engines were lubricated with Amsoil 10W40 synthetic oil, and Rockett Brand supplied the 93 octane unleaded fuel for our competition, requiring the engine builders keep compression at a street-friendly level. About the only other limitation in our rules was induction which was restricted to a total of 1,350 cfm.

The dyno portion of the Engine Challenge is held at Comp Cams' Memphis, Tennessee, research facility, and each engine is required to make three qualifying, then three judged dyno pulls between 3,000 and 7,000 rpm. The combined peak power and torque of the engine's single best pull is then factored into the cost of the engine's parts, for a power per dollar factor to determine the winner. Since we're all feeling the effects of the economy these days, this year's rules factored used parts at their fair market value, showing that a powerful engine could be built with a combination of new and "seasoned" items.

LaRoy Engines of Challis, Idaho, finished third in the 2009 contest, and ProMax Performance of Indianapolis, Indiana, finished a strong forth. Each of these engines combined power and economics to gain an advantage, both completing all of their pulls without incident. The father and son team of Jim and Cody LaRoy impressed everyone in attendance with their big horsepower numbers, and ProMax Performance made a solid showing with their economically built big-block. This month we'll show you what parts and techniques the third and forth place engine builders used to tweak big power from these Mopar V-8s.

LaRoy Engines
Challis, Idaho
As a small engine shop in rural Idaho, LaRoy Engines was a newcomer to our contest this year. Specializing in powerful Mopar engines, LaRoy Engines places high emphasis on accurate machining and porting cylinder heads for maximum flow. Though the LaRoys are too busy building engines to do much racing, Jim LaRoy did enter the 2008 DynoMax "Power to the Wheels" contest, placing third in the normally-aspirated class behind two other Mopars. For this year's Engine Challenge, father and son team Jim and Cody LaRoy decided rather than strictly going for the win by building a powerful budget motor, they'd rather show how much horsepower they could make while staying within our somewhat restrictive rules, building an all-out 452-inch pump-gas powerhouse.

On the dyno at Comp, the LaRoy entry fired immediately, sounding crisp and powerful. During their qualifying dyno pulls, Jim and Cody LaRoy tuned their engine for the weather conditions and headers of Comp's dyno cell, efficiently making more power with each pull. As one of the smallest displacement engines in the contest, this big-block got everyone's attention as it made consistent pulls at 700 plus horsepower. Through a series of air-bleed, jet, and ignition timing changes, Jim and Cody LaRoy netted a best pull of 723.4 horsepower and 568.8 lb/ft of torque for an impressive combined score of 1,292.2. Also noteworthy was the fact that this engine made an impressive 1.6 horsepower per cubic inch, the highest in the contest by that standard. Only one of this year's entries made more horsepower, one more, and it was some 50 cubic inches larger.