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572ci Big-Block - Mail-Order Strokers

Admit It, You've Always Lusted for a 572ci Big-Block and Now's Your Chance

By , Photography by Manufacturers

Induction

We won't spend a lot of time here, except that with large-displacement engines, the sheer size will make massive torque even when you build an engine where peak horsepower has the emphasis. We built a 496 a few years ago (“707 HP for $6,720,” Mar. '07) that included a cast crank, stock rods, a Comp mechanical roller 254/260-degree cam, 305cc AFR rectangle-port heads, an Edelbrock Victor, Jr, and an 850-cfm carburetor. Even with a relative big mechanical roller, this “small” Rat made 514 lb-ft at 3,000 rpm and peak torque came in at 5,400 with 603 lb-ft. So for our next 496, we've upped our game, and from our Rat-friendly friends we hear that a Dominator carburetor is worth some power. The research indicates that while 1,050 cfm seems like overkill, the wider spacing of the throttle bores improves mixture distribution and that, with the larger venturis, inlet air speed is reduced. This can be an advantage because high mixture velocities have to make that 90-degree turn from vertical to horizontal flow to enter the intake ports. Since fuel is heavier than air, the air makes the turn and fuel slams into the bottom of the intake manifold. This is why taller manifolds also help. With a Dominator carb, the slower air speed at high rpm has a better chance to make the turn. Of course, this also means that low-speed throttle response may be a little sluggish. That's the compromise with any street engine. For street use, this will also require some specific tuning to lean the idle and low-speed circuits in the carburetor to prevent running the engine excessively rich at part-throttle boulevard engine speeds.

Three-circuit Dominators have received a bad reputation as street carburetors, but the reality is that this added low-speed circuit could be leaned out just as easily as the idle circuit in order to produce acceptable part-throttle operation. This is where a wideband oxygen (WBO2) sensor can be used as an excellent tuning aid.


Short-Block Kits

Here's where the fun really begins. It is time-consuming and challenging to build your own short-block, unless you have all the proper tools for measuring, creating custom clearances, and assembling an engine. But you don't have to because there are multiple companies out there that make the difficult part easy by offering outstanding deals on assembled short-blocks. ATK has been assembling performance engines for years, and we ran across an attractive 540ci internally balanced package using a standard-deck Dart Big M block, a forged 4340 steel crank, a forged piston, and H-beam rods all for a Summit Racing price of $4,799. Given that the block goes for $2,250, this means you're getting an assembled and balanced short-block for an excellent price. This still requires the usual cam, valvetrain, heads, oiling system, and all the rest, but an assembled short-block is an excellent way to begin your big-block journey.

Along those same lines, Ohio Crankshaft offers the choice of a 509/540/555/565ci Rat using a Merlin block with a 4.250-inch steel crank, 6.385-inch H-beam rods, and forged pistons assembled for $4,395, or you can step up to a 572- or 588ci Rat still at the standard 9.8-inch deck height assembled for $4,995. Scott Shafiroff Racing is right there in the hunt with a 540ci assembled short-block that starts with a Dart Big M block, an Eagle 4340 crank and H-beam rods, JE/SRP forged pistons, and Clevite bearings all assembled for $4,595. Or if displacement envy is your thing, but with a standard deck motor, Shafiroff builds a 582ci Big Dawg motor with similar parts to the 572 for $4,845. At 1.25 lb-ft/ci, we're talking about a Rat that will twist nearly 730 lb-ft of torque. Think diesel-locomotive-level torque and then go from there.

There are many other examples, but by now you get the picture. Torque is what shoves you back in the seat in the middle of Second gear when wimpy motors have fallen off the torque curve. If we haven't got you thinking in terms of expansive valve covers and driveshaft-twisting torque, check your pulse.


572ci Big-Block Chevy

To put some real numbers to all this conjecture, Steve Brulé at Westech built a thumpin' street big-block a couple of years ago and put it on the dyno. As you can see from the numbers, this beast never fell below 600 lb-ft of torque and twisted more than 820 hp at a mild 6,400 rpm. What might really tweak the naysayers is that this was with a hydraulic roller cam. A quick rundown of the specs below includes a Dart Big M block, an Eagle crank and rods, Mahle 10.5:1 compression pistons, a Comp Cams hydraulic roller cam (271/274 duration with 0.680/0.647-inch lift and 112-degree LSA). The heads were a pair of Dart 355cc Pro-1 CNC heads with a Dart Dominator intake and a Holley 1150-cfm two-circuit Dominator carb. Brulé even used off-the-shelf roller rockers instead of an expensive shaft rocker system. This motor makes excellent torque down low and would be simple to maintain with the hydraulic rollers. This beast makes 600 lb-ft of torque at 3,200 rpm.


572ci Power

RPM Torque HP
3,200 603 367
3,400 617 400
3,600 639 438
3,800 659 477
4,000 671 511
4,200 682 546
4,400 693 580
4,600 710 622
4,800 729 666
5,000 737 701
5,200 738 731
5,400 736 757
5,600 729 776
5,800 717 791
6,000 704 804
6,200 691 816
6,400 675 823
6,600 655 823
6,800 631 817

SOURCES
Scoggin-Dickey Parts Center
5901 Spur 327
Lubbock
TX  79424
800-456-0211
http://www.sdparts.com
Westech Performance
11098 Venture Drive
Unit C
Mira Loma
CA  91752
951-685-4767
http://www.westechperformance.co
m
Summit Racing
Akron
OH
800-230-3030
330-630-0240
http://www.summitracing.com/
Crower Cams
6180 Business Center Court
San Diego
CA  92154
619-661-6477
http://www.crower.com
Scat Enterprises
3-10/-370-5501
http://www.scatenterprises.com
Brodix
301 Maple P.O. Box 1347
Mena
AR  71953
479-394-1075
http://www.brodix.com
Dart Machinery
353 Oliver Street
Troy
MI  48084
248-362-1188
http://www.dartheads.com
JEGS
101 JEGS Place
Delaware
OH  43015
800-345-4545
http://www.jegs.com
ATK High Performance Engines
1102 West North Carrier Pkwy
Grand Prairie
TX  75050
800-421-3746
http://www.atk-engines.com/
Callies Performance Products
901 South Union St
Fostoria
OH  44830
419-435-2711
http://www.callies.com
Eagle Specialty Products, Inc.
8530 Aaron Lane
Southaven
MS  38671
662-796-7373
http://www.eaglerod.com
Trick Flow Specialties
1248 Southeast Avenue
Tallmadge
OH  44278
330-630-1555
http://www.trickflow.com
Blueprint Engines
Kearney
NE
800-483-4623
http://www.blueprintengines.com
Edelbrock
2700 California St
Torrance
CA  90503
310-781-2222
http://www.edelbrock.com
Ohio Crankshaft
Greenville
OH
800-333-7113
ohiocrank.com
Chevrolet Performance
800-450-4150
http://www.chevroletperformance.
com
Shafiroff Race Engines
35 Davinci Dr.
Bohemia
NY  11716
http://www.Shafiroff.com
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21 comments
Mike Rosato
Mike Rosato

No replacement for displacement. Big blocks rule.

Pedro Perez
Pedro Perez

Camero craft worships cameros and ls. That stuff has been way overdone

Ben Earl
Ben Earl

Dan Edwards that is a Chevy big block not an LS

Howard Cooper
Howard Cooper

decided to go old school 10.5 454 in my 73 Vette

Billy Rice
Billy Rice

Nothing beats the cackle of a blown big block Chevy on alcohol.

Dan Edwards
Dan Edwards

I'd rather see an article stroking a Fiat 500 than ANOTHER LS .

Carroll Smith
Carroll Smith

any low buck LS-3 build ups coming? seeing the cylinder heads are capable of making so much h.p in stock form

Agapito Ramos
Agapito Ramos

That would be one hell of an engine, but 10k for the average joe is hard to come by.

Patty Williams
Patty Williams

My hubby built a 572 for his 55 chevy. Awesome sound & power

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