We also took the liberty of replacing the 36-pound injectors with a set of larger 50 pounders (run at 60 PSI), allowing us enough fuel to exceed 800 HP if need be. Run with the ATI (stock diameter) crank pulley, the 3.8-inch blower pulley and stock throttle body, the supercharger managed to provide only 2.5 PSI of boost to our ultra-efficient 383ci stroker. Swapping over to the smaller 3.0-inch pulley netted the desired peak boost level of 7.8 PSI at 6,000 rpm. Installation of the Vortech TS supercharger also required use of the complete FEAD front accessory drive including the manual water pump.

Visually the Vortech twin-screw supercharger made an impressive statement. We knew the forged internals from Pro Comp used in the 383ci were plenty capable of harnessing the power offered by the supercharged configuration and after tuning, we were rewarded with peak numbers of 671 HP at 5,800 rpm and 658 lb-ft of torque at 4,600 RPM. There was certainly more power to be had with more boost pressure, but we were quite happy at this point with the fact that torque production from the supercharged stroker exceeded 630 lb-ft from 3,000 RPM to 5,600 RPM, making for one sweet torque curve. Combining the supercharger and stroker improved the power output of the original 5.3L by over 300 HP and nearly a like amount of torque. Of course there is always more boost, as the Vortech system featured a dedicated air-to-water intercooler and would easily continue to cool the charge temperatures offered by another few pounds of boost. Either way, this supercharged stroker clearly demonstrated that not only is boost a replacement for displacement, but also maximum torque comes from combining both!

DYNO POWER NUMBERS

RPM
Stock LM7 (HP TQ)
Modified LM7 (HP TQ)
383ci Stock Intake (HP TQ)
383ci LSXRT (HP TQ)
383ci Vortech (HP TQ)

2900 187 339 199 360
3100 202 343 213 361 258 437 260 441 371 629
3300 218 347 228 363 271 431 275 437 400 636
3500 233 350 247 371 297 446 301 452 430 646
3700 249 353 272 386 325 461 332 471 459 652
3900 267 360 293 395 352 474 361 486 484 651
4100 287 368 317 406 373 478 384 492 509 652
4300 305 373 343 419 399 487 405 495 537 656
4500 315 368 369 431 421 491 432 504 563 658
4700 328 366 390 436 438 489 454 508 588 657
4900 340 364 408 437 455 487 471 505 606 649
5100 344 354 426 439 466 480 483 497 626 644
5300 344 341 442 438 472 468 495 490 644 638
5500 345 329 458 437 479 457 506 483 657 627
5700 348 319 469 432 480 442 510 470 669 617
5900 341 304 476 423 475 423 500 445 671 595
6100 337 290 481 414 467 402 486 419 665 572
6300 330 275 482 402
6500
MAX. 348 373 483 439 480 491 510 508 671 658