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Pontiac 400 Poncho Engine Build - A 650HP Hard-Core Pontiac Stroker

If You Own A Pontiac And Were Considering Bolting In A Big-Block Chevy To Make Some Real Horsepower-Shame On You! Repent While There's Still Time And Build...

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Flow Numbers
These flow numbers were generated on Westech's SuperFlow 600 bench using a 4.175-inch bore size at 28 inches of water test depression. While Mitchell's cam only lifts the valve to 0.675 inch, note how these heads continue to deliver flow improvements up to a staggering 1 inch of valve lift. These are as-cast flow numbers. Porting could easily push the intakes above 400 cfm.

CFM VALVE LIFT INTAKE EXHAUST E/I (PERCENTAGE)
0.100 72 61 85
0.200 145 114 78
0.300 220 142 64
0.400 273 166 61
0.500 303 186 61
0.600 330 202 61
0.700 349 211 60
0.800 358 220 61
0.900 373 230 62
1.000 385 240 62

The Test
The final assembly included adding the necessary Roland CV-1 single-plane intake manifold along with a 2-inch phenolic spacer topped off with a Holley Ultra Dominator 1,050-cfm three-circuit carburetor. Even though the motor was only 434 inches, the CV-1 heads seem to prefer a larger 2-inch primary header. Bolting up this completed package on Westech's dyno, Mitchell and Westech's Steve Brulé performed some quick jetting and timing exercises and then cranked out an impressive 650 hp at 7,000 rpm. On the other end of the curve, peak torque occurred at 5,500 rpm with 549 lb-ft, which outlined a wide powerband of 1,500 rpm. And there was no race gas here-this was on little more than California-conservative 91-octane. Mitchell says the owner was initially going to stuff this beast into an original '65 GTO but reconsidered, and it now occupies the engine compartment in a '69 Firebird. Just for fun, we plugged the power curve into a simulated 3,000-pound Firebird with a TH400, a 28-inch-tall tire, and a 4.10:1 gear using the Quarter Pro software. The sim reported a 9.90 at 135 mph, which should make any Pontiac owner proud. We certainly do live in the golden age of horsepower.

PONTIAC POWER
RPM TQ HP BSFC
4,600 525 460 0.445
4,700 525 470 0.439
4,800 529 483 0.436
4,900 534 498 0.437
5,000 538 512 0.436
5,100 543 527 0.434
5,200 547 541 0.435
5,300 548 553 0.432
5,400 548 563 0.429
5,500 549 574 0.429
5,600 549 585 0.430
5,700 549 596 0.431
5,800 546 603 0.432
5,900 541 608 0.433
6,000 536 612 0.431
6,100 530 616 0.429
6,200 524 619 0.429
6,300 519 623 0.434
6,400 515 627 0.437
6,500 511 632 0.439
6,600 507 637 0.443
6,700 503 642 0.445
6,800 499 645 0.451
6,900 493 648 0.460
7,000 488 650 0.469
Peak 549 650 0.429
Avg. 527.8 580.9 0.437

SOURCES
Westech Performance Group
Mira Loma
CA
951-685-4767
http://www.westechperformance.co
m
Kauffman Racing Equipment (KRE)
Glenmont
OH
740-599-5000
www.krepower.com
Comp Cams
3406 Democrat Road
Memphis
TN  38118
800-999-0853
www.compcams.com
Roland Racing
Springfield
MO
417-209-7395
www.rolandracing.com
Scat Enterprises Inc.
Redondo Beach
CA
310-370-5501
www.scatcrankshafts.com
SD Performance
Chilliwack
AK
604-392-2211
www.sdperformance.com
T&D Machine Products
Carson City
NV
775-884-2292
www.tdmach.com
Holley Performance Products
1801 Russellville Rd.
Bowling Green
KY  42101
270-781-9741
www.holley.com
BOP Engineering
N3651 Schmidt Rd
Jefferson
WI  53549
920-674-6058
www.bopengineering.com
Manley Performance
www.manleyperformance.com
JE Pistons
15312 Connector Lane
Huntington Beach
CA  92649
714-898-9763
http://www.jepistons.com
RPM
Cerritos
CA
800-981-0776
www.rpmmaxx.com
Pro-Gram Engineering
475 5th Street NE
Barberton
OH  44203
330-745-1004
www.pro-gram.com
Hardcore Racing
Montclair
CA
909-851-8251
Total Seal Inc
22642 North 15th Avenue
Phoenix
AZ  85027
800-874-2753
www.totalseal.com
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