434 Power Upgrades - Power Added

Big-inch small-block with a side order of go juice

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Making power is easy. It’s only a matter of understanding what you want and how far you’re willing to take it.

1207chp 01 O  434 Engine Power Upgrades Dyno 2/14

If you recall, back in the Mar. ’12 issue (“The Bigger Mouse”), we ordered a complete Dart 434ci SHP short-block stuffed with all forged internals, had 10.3:1 compression, and a COMP hydraulic roller camshaft. Up top, we completed the package with a set of Dart CNC 227 cylinder heads and fed the fire with a Holley Ultra HP 750 carburetor.

When Westech Performance Group’s SuperFlow 902 put our mill to the test, the end result was 542 hp/552 lb-ft on pump gas. Again, our intentions were to build a real-world street mill that could idle, be driven anywhere, and have big-block–like torque, with a healthy rumble.

Since then, we’ve decided to maintain the core of the combination and only port-matched the intake manifold (“Max Flow,” Jun. ’12, pg. 20). For the second round, we wanted to see what this gem would produce with a mild hit of nitrous; our system of choice was a Nitrous Oxide System Cheater kit, which is good for an additional 100-250 hp.

1207chp 02 O  434 Engine Power Upgrades Carburetor 3/14

Also, at the recommendation of Westech’s Steve Brulé, we swapped out the original Holley Ultra 750 HP for a 950 version. While the 750 worked well, Brulé felt the 434 would benefit from the larger carburetor. All said and done, between the port matching and the 950 hp, our baseline numbers improved 13 hp and 6 lb-ft to 555 hp/558 lb-ft.

The naturally aspirated numbers are impressive, but wait until you take a look at the nitrous results. Where do we go from here? Time will tell, but we think you’ll like what we have planned. Until then, read on to see how to transform a mild street combination into a track terror on command.

434 Buildsheet

Displacement 434
Bore x Stroke 4.155 x 4.000 inches
Compression 10.3:1
Rod center-to-center 6.00 inches
Piston deck height 0.000
Chamber volume 66 cc
Rod bearing clearance 0.0025 inch
Crank endplay 0.007 inch
Main bearing cap torque 1-5 / 7/16 bolts / 65 ft-lb (moly-lube)
2, 3, 4 / 3/8 bolts / 35 ft-lb (moly-lube)
Rod bolt torque 70 ft-lb (moly-lube)
Head bolt torque 80 ft-lb (moly-lube)

1207chp 08 434 Engine Power Upgrades Side View 10/14

At a glance

1. Dart SHP block with a 4.155-inch bore // 2. Dart single-plane manifold/Nitrous Oxide Systems Competition Cheater Plate System (PN 02010NOS) // 3. 13/4-inch headers with 18-inch extensions and mufflers // 4. Dart CNC 227 cylinder heads // 5. Holley Ultra HP 950-cfm carburetor (PN 0-80805HB) // 6. Eddie Motorsports custom-engraved valve covers

Dart Pro 1 CNC 227 Specs

Intake Port 227 cc
Chamber volume 66 cc
Intake/exhaust valves 2.08/1.60 inches

1207chp 10 O  434 Engine Power Upgrades Cheater System 11/14

Flow Data

Intake Exhaust
0.200 158 117
0.300 209 149
0.400 257 182
0.500 293 211
0.600 302 220
0.700 309 226
*cfm at 28 inches H20

Cam specs

Manufacturer COMP Cams
PN 12-433-8
Grind number XR288HR
Type hydraulic roller
Valve lift 0.520/0.0540 inch, intake/exhaust
Duration at 0.050 236/242 degrees, intake/exhaust
Lobe separation angle 110 degrees

Dyno Details

Headers 13/4-inch long-tubes
Advance Motor 40 degrees
100-shot 33 degrees
150-shot 33 degrees
Fuel 91 octane
Carb Holley 950 Ultra HP

1207chp 11 O  434 Engine Power Upgrades Inlet Port 12/14

Motor

RPM LB-FT HP
3,100 487 288
3,200 491 299
3,300 499 313
3,400 507 328
3,500 517 344
3,600 525 360
3,700 531 374
3,800 536 388
3,900 539 401
4,000 543 414
4,100 547 427
4,200 551 441
4,300 554 454
4,400 556 466
4,500 558 478
4,600 558 489
4,700 558 499
4,800 557 509
4,900 555 518
5,000 552 526
5,100 548 532
5,200 542 537
5,300 537 542
5,400 531 546
5,500 524 549
5,600 518 553
5,700 511 554
5,800 502 555
5,900 494 554
6,000 485 554
6,100 476 552
6,200 464 548
6,300 454 544
Max Torque 558 at 4,500
Max Power 555 at 5,800
Avg. Torque 524
Avg. Power 468

100-shot

RPM LB-FT HP
3,100 475 280
3,200 478 291
3,300 487 306
3,400 497 322
3,500 507 338
3,600 513 352
3,700 519 365
3,800 523 379
3,900 526 391
4,000 530 404
4,100 535 418
4,200 539 431
4,300 542 443
4,400 544 456
4,500 545 467
4,600 548 480
4,700 553 494
4,800 581 531
4,900 654 610
5,000 705 671
5,100 701 681
5,200 680 673
5,300 654 660
5,400 632 650
5,500 616 646
5,600 604 645
5,700 594 644
5,800 580 641
5,900 569 639
6,000 556 636
6,100 543 631
6,200 530 626
6,300 516 619
Max Torque 705 at 5,000
Max Power 681 at 5,100
Avg. Torque 563
Avg. Power 510

1207chp 12 O  434 Engine Power Upgrades Nitrous Solenoid Install 13/14

150-shot

RPM LB-FT HP
3,100 471 278
3,200 475 289
3,300 482 303
3,400 491 318
3,500 500 333
3,600 510 349
3,700 518 365
3,800 523 378
3,900 524 389
4,000 526 401
4,100 529 413
4,200 536 428
4,300 541 443
4,400 543 455
4,500 543 465
4,600 543 476
4,700 548 490
4,800 554 507
4,900 601 561
5,000 698 664
5,100 732 711
5,200 725 718
5,300 708 715
5,400 692 711
5,500 677 709
5,600 663 707
5,700 650 706
5,800 639 706
5,900 625 702
6,000 613 700
6,100 599 696
6,200 582 687
6,300 568 681
Max Torque 732 at 5,100
Max Power 718 at 5,200
Avg. Torque 580
Avg. Power 529

1207chp 13 O  434 Engine Power Upgrades Finished 14/14

Sources

Westech Performance Group
Mira Loma, CA
951-685-4767
WestechPerformance.com
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