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

RPM TQ: HP:
2,500 503 240
2,600 513 254
2,700 518 267
2,800 517 276
2,900 510 282
3,000 502 287
3,100 494 292
3,200 486 296
3,300 476 299
3,400 473 306
3,500 475 316
3,600 477 326
3,700 490 345
3,800 512 371
3,900 538 399
4,000 557 424
4,100 568 444
4,200 578 462
4,300 584 478
4,400 590 494
4,500 594 509
4,600 598 524
4,700 599 536
4,800 600 548
4,900 599 559
5,000 597 568
5,100 594 577
5,200 590 584
5,300 587 592
5,400 584 601
5,500 579 606
5,600 576 614
5,700 573 622
5,800 569 629
5,900 564 633
6,000 558 637
6,100 552 641
6,200 544 643
6,300 535 642
6,400 527 642
6,500 514 636