Small-Block Top-End Swap - Big Power For Little Cash
TEST FOUR Replacing the 750-cfm with an 850-cfm Mighty Demon produced almost no change. Our power numbers stayed very close to as before. *850 Mighty Demon
*Edelbrock Victor Jr. single-plane
*AFR 195 Street Eliminator cylinder heads
*Comp Cams Xtreme Energy 284 cam w/1.6:1 roller rockers
*Westech custom headers with 3-inch collectors
*Jets: Primary: 78 changed to 75; Secondary: 80 changed to 78 | RPM | Torque | HP | RPM | Torque | HP | | 3,000 | 392 | 224 | 4,800 | 469 | 429 | | 3,100 | 396 | 234 | 4,900 | 471 | 440 | | 3,200 | 403 | 246 | 5,000 | 474 | 451 | | 3,300 | 412 | 259 | 5,100 | 476 | 462 | | 3,400 | 420 | 272 | 5,200 | 478 | 473 | | 3,500 | 428 | 285 | 5,300 | 477 | 482 | | 3,600 | 434 | 298 | 5,400 | 473 | 487 | | 3,700 | 441 | 311 | 5,500 | 468 | 490 | | 3,800 | 447 | 324 | 5,600 | 462 | 493 | | 3,900 | 452 | 336 | 5,700 | 458 | 497 | | 4,000 | 455 | 347 | 5,800 | 454 | 501 | | 4,100 | 456 | 356 | 5,900 | 450 | 506 | | 4,200 | 457 | 366 | 6,000 | 447 | 511 | | 4,300 | 459 | 376 | 6,100 | 443 | 514 | | 4,400 | 461 | 386 | 6,200 | 439 | 518 | | 4,500 | 463 | 397 | 6,300 | 431 | 517 | | 4,600 | 465 | 407 | 6,400 | 422 | 515 | | 4,700 | 467 | 418 | Average | 442 | 378 |
TEST FIVE For this test we added a High Velocity Heads (HVH) 2-inch carb spacer and picked up a couple more horses at peak power, bringing the total to 521. *850 Mighty Demon
*Edelbrock Victor Jr. single-plane
*AFR 195 Street Eliminator cylinder heads
*Comp Cams Xtreme Energy 284 cam w/1.6:1 roller rockers
*Westech custom headers with 3-inch collectors
*Timing: 37.5 total
*Jets: Primary: 78 changed to 75; Secondary: 80 changed to 78
*Carb spacer | RPM | Torque | HP | RPM | Torque | HP | | 3,000 | 387 | 221 | 4,800 | 469 | 429 | | 3,100 | 392 | 232 | 4,900 | 472 | 440 | | 3,200 | 401 | 244 | 5,000 | 474 | 451 | | 3,300 | 410 | 257 | 5,100 | 477 | 463 | | 3,400 | 416 | 270 | 5,200 | 478 | 474 | | 3,500 | 423 | 283 | 5,300 | 477 | 481 | | 3,600 | 431 | 295 | 5,400 | 473 | 486 | | 3,700 | 437 | 308 | 5,500 | 468 | 490 | | 3,800 | 444 | 321 | 5,600 | 464 | 494 | | 3,900 | 451 | 335 | 5,700 | 460 | 499 | | 4,000 | 454 | 346 | 5,800 | 457 | 505 | | 4,100 | 455 | 355 | 5,900 | 455 | 511 | | 4,200 | 457 | 365 | 6,000 | 452 | 517 | | 4,300 | 459 | 376 | 6,100 | 447 | 520 | | 4,400 | 462 | 387 | 6,200 | 442 | 521 | | 4,500 | 464 | 398 | 6,300 | 433 | 520 | | 4,600 | 466 | 408 | 6,400 | 424 | 517 | | 4,700 | 467 | 418 | Average | 441 | 378 |
TEST SIX Finally, we added an S&B 4x15-inch air filter, fired up the dyno, and recorded 523 hp. A number of variables can account for the increase, but the point to drive home is that the filter certainly didn't hurt the performance. *850 Mighty Demon
*Edelbrock Victor Jr. single-plane
*AFR 195 Street Eliminator cylinder heads
*Comp Cams Xtreme Energy 284 cam w/1.6:1 roller rockers
*Westech custom headers with 3-inch collectors
*Air filter w/spacer
*Jets: Primary: 78 changed to 75; Secondary: 80 changed to 78 | RPM | Torque | HP | RPM | Torque | HP | | 3,000 | 394 | 225 | 4,800 | 473 | 433 | | 3,100 | 398 | 235 | 4,900 | 475 | 443 | | 3,200 | 405 | 247 | 5,000 | 477 | 454 | | 3,300 | 414 | 260 | 5,100 | 479 | 465 | | 3,400 | 422 | 273 | 5,200 | 480 | 475 | | 3,500 | 429 | 286 | 5,300 | 479 | 484 | | 3,600 | 434 | 298 | 5,400 | 476 | 490 | | 3,700 | 441 | 311 | 5,500 | 472 | 494 | | 3,800 | 449 | 325 | 5,600 | 467 | 498 | | 3,900 | 456 | 338 | 5,700 | 462 | 502 | | 4,000 | 459 | 350 | 5,800 | 459 | 507 | | 4,100 | 461 | 360 | 5,900 | 455 | 511 | | 4,200 | 462 | 370 | 6,000 | 452 | 516 | | 4,300 | 465 | 381 | 6,100 | 448 | 520 | | 4,400 | 467 | 392 | 6,200 | 443 | 523 | | 4,500 | 469 | 402 | 6,300 | 435 | 522 | | 4,600 | 471 | 412 | 6,400 | 425 | 518 | | 4,700 | 472 | 423 | Average | 446 | 391 |
The Prices | MFG | PN | Description | Price | | AFR | 1040 | 195 Street Eliminator heads | $1,400 | | Comp Cams | 7972-16 | Chrome-moly 516-inch pushrods, 7.800-inch | $125 | | Comp Cams | 812-16 | Hydraulic Lifters | $70 | | Comp Cams | 1301-12 | Pro Magnum Roller rockers 1.52 | $260 | | Comp Cams | 1305-16 | Pro Magnum Roller rockers 1.60 | $260 | | Comp Cams | 12-246-3 | Xtreme Energy hydraulic cam XE274H | $105 | | Comp Cams | 12-250-3 | Xtreme Energy hydraulic cam XE284H | $105 | | Demon | 5402010 | Mighty Demon 850 Carburetor | $500 | | Edelbrock | 7501 | Performer RPM Air Gap | $206 | | Edelbrock | 2975 | Victor Jr. | $186 | | Fel-Pro | 1205 | Intake gasket | $14 | | 1003 | Head gasket | 2 @ $33 | |
All components were sourced through AFR and Summit Racing.
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