Mid America Racing EnginesWashington, IowaEngine 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.