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Merlin/Motion 540-Cube Big Block Engine - The Great American Supercar Engine

Joel Rosen Is Back In Motion With His 21st Century '69 Camaro SuperCoupe And Its 540-Cube Big-Block

By Paul Zazarine, Photography by Paul Zazarine, Bill Erdman

Tuning the Tubes
The Kinsler Cross Ram injection system was first used in 1974 by road racer John Greenwood on his big-block Corvettes. Since the rules disallowed stacks poking through the hood, Kinsler laid them down and designed the Cross Ram configuration. The Cross Ram injection system has evolved from Lucas mechanical metered injection to the Merlin/Motion's sequential electronic fuel injection using Bosch 44-pound injectors, controlled by an Accel/DFI GEN VII computerized engine management system.

Because of the precision of its EFI system, the Kinsler Cross Ram injection manifold is the perfect induction system for the Camaro SuperCoupe. In fact, the intake's pattern is so complex, the foundry can only pour one manifold a day. Like the Merlin/Motion engine, each Kinsler intake is hand machined and hand built, so no two are exactly alike

The intake was modified to meet Motion's specifications. The throttles measure 2 3/8 inches and the Bosch 44 injectors are mounted low in the ports. The Kinsler intake is designed to have either upper or lower injector locations. Rosen and Keech preferred the lower position, so the upper boss was removed from the manifold. Kinsler coordinated with Mitchell to port the intake to match the Merlin III cylinder heads.

The concept of Cross Ram injection is simple. The tube length affects the torque and horsepower peaks are in the rpm band. Typically, a shorter tube produces more top end while a longer tube provides more bottom end. The tube's diameter is determined by hp and maximum rpm.

Predicated on camshaft selection, engine displacement, and flow characteristics, Motion and Kinsler ran computer simulations to determine the proper length and diameter for the ram tubes. In the case of the Merlin/Motion 540, the ram tubes are 6 inches long with an inside diameter of 2.50 inches.

The throttle size was reduced to give the engine good driveabilty, but still provides plenty of volume so it will flow enough to hit the hp curve's "sweet spot." The Merlin/Motion 540 with the Kinsler Cross Ram EFI injection and custom Motion grind roller camshaft produces an estimated 700-plus-hp at 6,500 rpm and 585 lb-ft of torque at an estimated 5,200 rpm.

By Paul Zazarine
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