Mopar Stroker Small Block - The 2007 AMSOIL/Mopar Muscle Engine Challenge

It takes horsepower to be competitive in our Engine Challenge, and the two small-blocks we're featuring this month made plenty of it. In fact, the R.M. Competition entry was just shy of winning, placing a very close Third in our tightest competition to date. The Mid America Racing Engines entry also impressed us by making the most combined power of any engine in this year's Engine Challenge, screaming to more than 560 pump-gas-friendly horsepower and nearly 500 lb-ft of torque. Equally as important as the power these engines produced was the budget the builders adhered to. Since the cost of each engine is factored into the combined power, engine builders had to carefully spend money where it benefited their combination the most.

This month, we'll go inside the Third Place entry of R.M. Competition and the Fourth Place entry of Mid America Racing Engines, detailing the parts and techniques that made each engine competitive.

R.M. Competition
Roseville, Michigan
Engine builder Randy Malik came very close to winning this year's Engine Challenge. Placing a close Third, this engine was mere decimals away from the Second and First Place entries in ouandy placed so well was his careful selection of budget parts, and making more than 500 hp on the dyno certainly didn't hurt. This engine was a well thought-out combination of powerful parts and was built on a tight budget since cost matters as much as power in our contest.

Starting with a production Chrysler 360 core motor, Randy performed the necessary machine work in-house. The factory block was bored to accommodate Keith Black hypereutectic cast pistons and Perfect Circle piston rings. A Scat stroker crank was matched with factory connecting rods to net a displacement of 406 ci. A production 360 oil pan was also utilized to keep costs down, and a custom windage tray was fabricated in-house. Melling was the manufacturer of choice for the oil pump, timing set, and lifters, and Federal Mogul and Durabond bearings were used in this engine. Knowing the importance of camshaft selection, Randy chose a large Lunati flat-tappet unit to work with the Weiand tunnel-ram intake.

To top his stout bottom-end, Randy chose Mopar Magnum cylinder heads from Engine Quest. Magnum heads adorned the top three finishers in this year's contest and make great power for the money. REV engine valves were utilized along with valvesprings matched to the Lunati bump stick. Harland Sharp roller rocker arms with a 1.7 ratio were used on the intake side, while Crane 1.6 ratio rockers were chosen for the exhaust side. A composition head gasket was used to seal the combustion chambers, and Randy claims compression ended up right at 12.2:1, pushing the limit for pump gas. While the Weiand tunnel-ram intake isn't really what Randy would recommend for a street car, it worked great on the dyno where peak horsepower and torque were used to help determine the winner. While no special coatings per se were used on this engine, he did paint the bottom of the intake with epoxy paint to help insulate the intake from the hot oil. A matching pair of Edelbrock carburetors topped the engine, and an air cleaner was fabricated from wood, again to keep cost down.

Mid America Racing Engines
Washington, Iowa
Engine builder David Bruns of Mid America Racing Engines has brought competitive engines to all our competitions to date. The Hemi he brought to the first Challenge was a solid street engine with very broad torque and power curves, and last year's big-block impressed us with awesome power and torque, winning the '06 Engine Challenge. This year David brought yet another good engine to the contest, impressing everyone in attendance by making nearly 570 hp and 490 lb-ft of torque for a contest-leading combined score. While the expense of aluminum cylinder heads and a roller cam kept him from another win, we were still impressed with the power and reliability of this engine, earning Mid America Racing Engines a Fourth Place finish.

Like most competitors this year, David used a stock 360 core block as the foundation for his build. The block was machined in-house for Probe forged pistons with PBM piston rings and an Eagle 4-inch stroke crankshaft. Scat connecting rods were utilized for their durability; the compression ratio of this 410ci small-block was 11.7:1. To handle oiling, David chose a Moroso oil pan, which he modified by adding oil control baffles, combined with a Milodon windage tray and Clevite oil pump. Oil from the top end was routed to the pan via the back of the block and away from the rotating assembly by metal plates under the camshaft tunnel. King rod and main bearings kept everything spinning freely, and Clevite cam bearings held the Cam Motion solid roller camshaft in place. A PBM timing set was used to spin the cam and enclosed by a stock timing cover.

Going for big power numbers meant utilizing aftermarket cylinder heads, and engine builder David Bruns chose Indy 360 H1-1 units to top his engine. These heads were machined in-house for stainless steel 2.125-inch intake and 1.65-inch exhaust valves and PBM roller valvesprings. David also ported the cylinder heads himself, reshaping the exhaust ports to mimic the proven profile and volume of Mopar W-2 cylinder heads. To actuate the valves, 1.6-ratio Indy roller rocker arms were used along with 3/8 -inch-diameter hardened pushrods. Knowing this combination would like an intake with big runners and a high plenum volume, David chose the Indy 360-14-3R aluminum single plane intake for induction duties. Double carb spacers beneath the Holley 1,000-cfm 4150 series carb provided additional intake volume, and additional power for this combination. Ignition was handled by an MSD distributor.