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Small Block Chevy Holley Carb Tests - Danger Mouse Part 8

Carbureting For Power

By Mike Petralia
670-cfm vs 750-cfm vs HP750 dp 800-cfm dp 830-cfm dp
(0-80670) (0-3310-5) (0-80528-1) (0-4780-6) (0-9381)
RPM TQ HP TQ HP TQ HP TQ HP TQ HP
2500 344 164 337 160 356 169 343 163 340 162
3000 391 223 386 221 401 229 404 230 402 230
3500 403 269 388 259 416 276 410 274 416 277
4000 417 317 394 300 429* 327* 424* 323 422 321
4500 411 352 396 340 422 362 418 358 420 360
5000 401 381 388 370 414 394 406 387 407 387
5500 373 391 371 389 388 407 379 397 380 398
6000 332 379 331 379 343 392 336 384 341 389
Peak 419 391 400 391 431 408 427 399 427 403
@ 4100 5600 4300 5700 4100 5600 4200 5700 4200 5700
Avg 390 315 380 307 403 325 398 321 398 321
850 dp HP950 dp
(0-4781-8) (0-80496-1)
RPM TQ HP TQ HP
2500 347 165 353* 168*
3000 406 232 407* 232*
3500 412 274 414 276
4000 427 325 429* 327*
4500 421 361 424* 364*
5000 409 390 415* 395*
5500 384 402 390* 409*
6000 341 389 347* 396*
Peak 429 403 432* 409*
@ 4100 5700 4200 5500
Avg 401 323 404* 326*

* = Indicates highest figure recorded
*t = Indicates a tie for highest figure

Some Interesting Dyno Observations
*Only three (850 dp, HP750, and HP950) of the carbs averaged over 400 lb-ft of torque, and only the two HP carbs (750 & 950) peaked over 430 lb-ft of torque.
*The HP950 made more torque at 2,500 rpm (353 lb-ft) than any other carb, but the 650 dp was right behind it with only 1-less lb-ft (352).
*The 650 and 750 dps tied for most tq and hp at 3,500 rpm.
*The 750 vacuum secondary carb (List 0-3310) had the lowest mid-range figures of all carbs.
*Peak torque occurred between 4,100 and 4,300 rpm, and peak hp occurred between 5,400 and 5,700 rpm with every carb.
*Average power tells the story and the two HP carbs (750 and 950) made more average power than any other carb.
*Note: Faithful DM followers may note that peak power numbers for this test were down by a couple percent from previous tests. That discrepancy is most likely just the difference between how a DTS dyno and a Superflow dyno collect and interprets the data. It's kind of like stepping on the scale at your house vs. your friend's house; either scale may be correct, but you'd still weigh the same regardless of the difference in readings.

By Mike Petralia
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