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Installing 557 Demon Stroker Kit - The Demon Stroker Kit For Big-Block Fords

Don't Rev That Small-Block To The Moon. Make More Power Using . . .

By Richard Holdener, Photography by Richard Holdener

One way around the driveability issue is through increased displacement. If we retain our goal of 600 hp but increase the displacement of our motor to 557 ci, we see that we have reduced the specific output to just 1.077 hp per cubic inch (the equivalent of a 325hp 302). It is not only much easier to produce 600 hp using a 557 than a 460, but the resulting combination will offer improved torque production, driveability, and engine life owed to the decrease in operating speed. A 600hp 460 will likely make peak power at or near 6,500 rpm, while the same power output from this 557 came in at just 5,600 rpm. Obviously, a stroker kit will cost more than pulling a used 460 from the wrecking yard, but not a lot more, since Demon Engines offers low-buck stroker kits (some as low as $1,800) designed specifically for the 460 Ford. The company's 557 stroker kit (other displacements are also available) for the 429/460 Ford consists of a 4.5-inch steel crank combined with a set of 6.7-inch forged-steel H-beam rods and forged flat-top pistons from Probe Racing. Different bore sizes are available, but this particular buildup features an increase in bore size from 4.36 to 4.44 inches. When combined with a jump in stroke from 3.85 to 4.5 inches, the result was an increase of nearly 100 ci (to 557 cubes).

We followed along while Demon Engines assembled one a 557 stroker kit for a customer. This particular build included three upgrades that could be easily eliminated to reduce costs. They included a (mild) solid roller cam, a Weiand tunnel-ram, and a pair of CNC-ported ProComp aluminum heads. The ProComp heads were still high on the affordable scale, especially when you compare the flow rates with their stock cast-iron counterparts. But know that the 557 could be just as easily run with a single four-barrel intake, a hydraulic flat-tappet cam, and a pair of stock (possibly ported) iron 460 heads. The power output would be down somewhat with the stock heads, but the flat-tappet cam and single-four-barrel intake would work well on the larger motor.

The owner set a realistic goal for this particular buildup of 600 hp. More important, the idea was for the stro-ker to offer a massive torque curve that easily exceeded 600 lb-ft, as having a veritable tidal wave of torque is considerably more fun and usable on a daily basis than having a big peak power number. Think about how much time your motor spends running at the power peak compared with those short bursts through the meaty part of the torque curve. Running a big-block like this will all but eliminate the need for downshifting to get the motor up on the cam. Traction will be much more of an issue than finding enough power to pass that pesky import.

With torque production in mind, the 557 stroker kit was assembled using the Demon stroker kit, ProComp aluminum heads, and a Comp roller cam. The finished products offered a pump-gas-friendly static compression ratio of 10.3:1 (given the aluminum heads), and the tunnel-ram ensured plenty of visual appeal along with further improvements in the torque curve. With the crankcase full of Lucas Oil, the 557 eventually spit out our peak numbers of 615 hp at 5,600 rpm and 658 lb-ft at just 4,100 rpm. Torque production exceeded 650 lb-ft from 3,600 rpm to 4,600 rpm and remained above 600 lb-ft all the way out to 5,350 rpm. A similar Demon 557 stroker equipped with TFS A460 heads exceeded 900 hp in normally aspirated trim and more than 1,100 hp with nitrous, so you know the stroker assembly is plenty stout. All it'll take now is a phone call and/or a trip to the wrecking yard.

By Richard Holdener
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