Although we doubt we'll ever see one of these in anything that remotely resembles a street car, we sure hope someone proves us wrong. By spreading out the center mains in its 5000-series aluminum block, Brodix has increased the Rat motor's 4.840-inch bore spacing to 5.000 inches. In conjunction with a 11.600-inch deck and cam bores that have been raised a full inch, this behemoth can ingest a 5.500-inch crank. Matched with a 4.750-inch bore, that's good for 780 ci. The truly wacky part about it is that Callies stocks the cranks needed for this combo in its warehouse, although custom pistons are a must. Brodix has a set of heads that flow 557 cfm and will bolt right up, and Brodix is currently working on an intake manifold as well. At a hair under $7,000 just for a block, a combo like this is cost-prohibitive, to say the least.
Pricing It Out
To get a better idea of what it costs to assemble a stroker short-block, we've priced out a couple of theoretical buildups. Although it sometimes gives you less flexibility in spec'ing out your combo exactly how you'd like, purchasing bundled rotating assemblies is a great way to save cash. The Powerhouse 434 rotating assembly used in our small-block build includes a 4.000-inch forged 5140 crank, 6.000-inch I-beam rods, forged pistons, rings, bearings, a flexplate, and an SFI balancer. For our big-block build, we opted for a Scat 540 rotating assembly featuring a 4.250-inch forged 4340 crank, 6.385-inch H-beam rods, forged pistons, rings, bearings, a flexplate, and a balancer. Furthermore, since it makes little sense these days to monkey around with machining a production block, we've based these builds on aftermarket units instead.
Much to our surprise, our final tally was less than expected. The 434 rang up a total of $3,353, while the 540 set us back $4,475. Out of curiosity, we compared our figures to comparable turnkey short-blocks on the market. Again, the difference was less than expected. Coast High Performance sells a Dart-block-based 427 with forged 4340 internals for $4,620. Factor in the cost of professional assembly and its higher-grade internals when compared to our 434, and the $1,267 price difference is almost a wash. Likewise, Coast's Dart-block-based 540 with forged 4340 internals lists for $5,000, just $380 more than our theoretical buildup. The bottom line: If a reputable shop offers a turnkey short-block with similar specs to what you're thinking about building, it may not cost that much more than building it yourself.