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Small Block Chevy Build - Sleeper Combo Part II

Don't Let That Loudmouth Forum Troll Put You Down. Dominate Him With The Sleeper Combo Part II

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Step Three
Millerspeed Cog Drive Pulleys
431 hp at 5,300
479 lb-ft at 3,900

We've heard claims that slowing down the water pump and alternator frees up horsepower. Since changing the intake manifold also required changing the alternator bracket, we decided to test the claim. Millerspeed, a small company out of Hermosa Beach, California, offers a set of billet brackets and cogged pulleys that reduce the water pump speed to a 1:1 ratio and the alternator to 1.92:1. We normally don't give billet a second look, but the supercharger-like cogs and high-rpm whine reminded us of an 8-71, so we gave in. Owner Alistair Miller also claims the overall design of the cog drive is more efficient because it lacks the requisite tension of a V-belt pulley, a trait that might also be worth some power.

The result was a 9hp gain using the 1-inch or 2-inch pulley system plus a satisfying sound that will alert the guy in front of you that you don't like his Prius. Selecting the correct system is a matter of space under the hood.

Pulley Test Results
The stock pulley test was performed with the E-Street heads, the Air-Gap intake manifold, and 500-cfm AVS carburetors. We added a GM alternator and factory-style V-belts and loaded it by spinning an electric cooling fan. The 2-inch pulleys were added for the second test using the same GM alternator loaded with the same electric cooling fan. We then tried the 1-inch-width pulleys and saw no difference.

  Stock Pulleys 2-Inch Pulleys
RPM LB-FT HP LB-FT HP
2,500 427 203 429 204
2,600 422 209 425 211
2,700 418 215 422 217
2,800 416 222 420 224
2,900 417 230 420 232
3,000 421 240 424 242
3,100 429 253 432 255
3,200 438 267 441 269
3,300 447 281 450 283
3,400 455 294 458 297
3,500 461 307 465 310
3,600 466 319 471 323
3,700 470 331 476 335
3,800 472 342 478 346
3,900 473 351 479 356
4,000 472 359 479 365
4,100 471 368 478 373
4,200 471 376 478 382
4,300 469 384 477 391
4,400 467 391 475 398
4,500 463 397 471 403
4,600 459 402 466 408
4,700 455 407 461 413
4,800 450 411 457 418
4,900 445 415 452 422
5,000 439 418 447 425
5,100 433 420 441 428
5,200 426 422 435 430
5,300 418 422 428 431
5,400 409 421 419 430
5,500 400 419 409 429

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