With the internal hardware in place, what remained was to dress the engine with the final components needed for a running assembly. A Meziere water pump and ATI damper finished off the front of the engine, while a set of Schoenfeld headers were bolted on to handle the exhaust. The 1.75-inch primary diameter headers were fitted with merge collectors, and that helped the midrange output and average torque, with a small penalty in outright peak horsepower. Experimenting with header primary tube length showed the longer tubes tilted the torque curve to favor the lower rpm range, while less tube length had the opposite effect, while the average power over the full rpm range remained little changed.
Deliver The Numbers
This engine was built with one goal in mind, and that was to maximize its power output between 2,500 and 6,500 rpm. That means that the torque comes in like a sucker punch right off the bottom—where you least expect it—and keeps coming at you as the needle on the tach swings to the sky. Right off the bottom at just 2,500 rpm, this combination assaults the senses with over 500 lb-ft on tap. From that start, torque piles up in abundance, pouring on the twist until a peak of 600 lb-ft is reached at 4,800 rpm. That’s over 1.4 lb-ft per cube of shove, and it’s on pump gas. Of course, anytime the torque comes on like a wrecking crew, the horsepower is following close behind. On the dyno, the power numbers rolled in at 643 hp at 6,200 rpm—plenty of output to prove a point.
On The Dyno Racing Engine Design 426 LS