A Dart 450ci Small-Block for Axle-Snapping Torque
Everyone talks torque, but do they really mean it? After all, small-block Chevys are the omnipresent four-wheeling powerplants, but small-blocks are unlikely cohorts with huge torque numbers. Even if you build a 383 stroker that visits the neighborhood of 500 lb-ft, it probably has a choppy cam with no low-end driveability and clouds of pig-rich, 91-octane exhaust fumes. But what if you could have big-block cubes in a small-block package?
You can. Using a Dart Iron Eagle block with a raised cam and deck height (make sure to read the sidebar), we built a 450ci small-block by combining a 4.165-inch bore with a 4.125-inch stroke. A normal 350ci Chevy is 4.00x3.48, and a 383 stroker is 4.03x3.75. Our big-inch, 9.3:1-compression small-block runs on 87-octane dog water (perfect for those Baja trips) and grunts out over 500 lb-ft from 2,000 clear through 5,000 rpm, peaking at a stout 571 lb-ft at a low 3,700 rpm.
It's only incidental that it also spits up 480 hp at a mere 4,900 rpm. If you can't frag your transfer case with this thing, something's wrong with you.But also know this: When you see a magazine pat itself on the back for big numbers on the dyno, those numbers are generated at wide-open throttle. That's only relevant to a mud-bogger, a dune-flogger, or to a total hack of a rockcrawler. For a rock-hound with finesse, it's more important to consider lug-ability (how low will it pull?) and part-throttle control, both of which are compromised by small cubes and big cams.
That's why our 450-incher benefits from a miniature Comp Cams hydraulic roller for an idle of 600-700 rpm with no lope whatsoever and a vacuum reading of 16 to 17 inches. That'll be happy with any power-brake system, run smoothly with an EFI setup, and pull as low as 300 rpm under load. And, since many of you will still want more, we also tried a bigger cam for 530-plus hp at 5,200 rpm, and then we gave a shot with a blower for you show-truck guys. How's 700 lb-ft and 720 hp grab you? Read on.