On this engine, the mountain-like...
On this engine, the mountain-like dome of the Hemi slug contributes to a compression ratio of about 9.5:1.
Between the big-flowing heads is an Indy 9.25-inch-tall aluminum intake and an AED-built 1050 Dominator carb. It's a pretty simple combination that relies on the engine's large displacement and a generation's worth of airflow research to make big power. On World Products' engine dyno, our project engine put up some very impressive numbers, with the best being 776.8 horsepower at 7,100 rpm and 641.7 lb.-ft. of torque at 5,800 rpm.
Designed for the high-rpm power needs of the drag strip, our aluminum Hemi project engine crossed the 500-horsepower mark soon after 4,000 rpm, hitting the 600-horse level by 5,100 rpm, and the 700-horsepower threshold by 5,800 rpm. In fact, the horsepower climbed steeply to its 776.8 peak and was still making 771 horses at the test's 7,300-rpm limit.
That's a great power curve and a stellar rev range for a 572-inch Hemi and its mechanically mild valvetrain. And considering it weighs less than 600 pounds in its dyno trim, it's a lightweight powerhouse, too. Even better, it's got a street-able 9.5:1 compression ratio.
Eagle forged steel H-beam...
Eagle forged steel H-beam connecting rods are connected to the extra-large pistons. They are 7.100 inches long, and held in place with nuts on studs rather than a conventional rod bolt. This enables a more accurate final-torque setting.
World Products' aluminum Hemi definitely has the juice to yank the front tires and pull your Mopar down the 1,320 with the ferocity reminiscent of the good-old days-and with its good idle quality and pump-gas compression ratio, you could drive that track star to and from the strip.
The good-old days were never this good.
|At A Glance|
|Cylinder block||World Products aluminum Hemi|
|Compression ratio||9.5:1 (approx.)|
|Rotating assembly||Forged crankshaft, rods, and pistons|
|Camshaft type||Hydraulic roller|
|Camshaft lift||.381-in. intake; .381-in. exhaust|
|Cylinder heads||Indy 426-1RA|
|Cylinder head airflow||510 cfm (intake) at 28 inches of water|
|Valves||2.400-in. intake; 1.940-in. exhaust|
|Induction||Single-plane manifold w/1050 Dominator|
|Peak horsepower||776.8 at 7,100 rpm|
|Peak torque (lb.-ft.)||641.7 at 5,800 rpm|
|Test weight||527 lbs.|
To make room for longer-stroke...
To make room for longer-stroke combinations, World Products modified the Hemi block's oil pickup locations, but even with that, the longest-stroked combinations would encounter interference. So, the block also has provisions to accommodate an externally mounted oil pump. This allows the use of a block-off plate for the original-style pickup to be installed (seen here) inside the block, freeing up space for long-reaching connecting rods.
The camshaft is a solid roller...
The camshaft is a solid roller that delivers .381/.381-inch lift and 258/266 degrees of duration on a 114-degree lobe separation angle. It has a comparatively small base circle that enhances valve lift, while the larger lobe separation supports a wider power band and greater upper-rpm power. The camshaft is located in the original position, allowing for a standard double-row, roller timing set. World Products also offers the Hemi block with the cam position raised .250-inch for builders using the maximum 4.750-inch stroke. That setup, however, requires a custom front drive system.
Despite the oil system revisions...
Despite the oil system revisions in order to accommodate the long-stroke rotating assembly, a conventional, off-the-shelf oil pan can be bolted on the block. This one's from Milodon and has a 7-quart capacity. Note the 12-AN fitting for the external oil line.
The lungs on our engine are...
The lungs on our engine are Indy's 426-1RA Legend heads. Compared to stock Hemi heads, they feature raised intake and exhaust ports, as well as exhaust valves canted 2 degrees toward the cylinder wall for greater clearance. Indy rates the airflow at 510 cfm on the intake side (at 28 inches of water).
The externally-mounted oil...
The externally-mounted oil pump is a racing-style pump that can flow up to 21 gpm, but works well on the street, too.
A 7-inch-tall Indy, single-plane...
A 7-inch-tall Indy, single-plane intake manifold supports the small-for-a-Hemi AED-prepped 1,050 Dominator carb.