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460 Big Block - Colossal Kaase Combo
Our Large and In Charge Big-Block Dyno Mule Returns
OK, we know it has been more than a year but we finally got around to Part 3 of Large and In Charge. Those with better-than-average memories will recall that we started out on this adventure with a stock 460 Ford (circa 1968) pulled from a wrecking yard. Step-by-step the big-block was upgraded with an intake and carb, roller rockers, mildly ported stock heads, and a small performance cam. The upgrades we showed you in the first part (May '11) pushed the power output from 349 hp and 492 lb-ft of torque to 437 hp and 507 lb-ft of torque. Part 2 stepped things up even further, with forged flat-top pistons, fully ported heads from MPG Heads and a custom solid flat-tappet cam from Cam Research Corp. These upgrades (June '11) combined with a single-plane intake and Holley carb allowed the 0.060-over 460 to exceed 600 hp, with peak numbers of 609 hp and 557 lb-ft of torque. This was a stout 460 to be sure, especially when you consider the use of iron heads, but we knew there was more power lurking within the 460 just waiting to be unleashed.
As big-blocks go, the factory 460 Ford was already sporting some impressive displacement, easily eclipsing the 440 Dodge, the 454 Chevy, and the 455 Buick and Pontiac offerings--only the massive 472- and 500-inch Cadillac engines offered more displacement. The stock displacement on the 460 came courtesy of a 4.36-inch bore combined with a 3.85-inch stroke. Though the big-bore combination suggested a candidate for high-rpm use (even more so for the smaller 429 with the 3.59 stroke), the 460 was primarily used by Ford for low-rpm towing and heavy hauling applications.
As big as the 460 is in stock configuration, the best way to improve the power (and more importantly torque) output is to make it even bigger. A little math here goes a long way toward explaining the benefit of the extra inches. Suppose we choose a power output for our racy 460 of 800 horsepower. Producing 800 hp from a 460 equates to a specific output of 1.739 hp per cubic inch, about the equivalent of a 525hp 302. Reaching this specific output with the 460 would be difficult, but not impossible. It would, however, require a whole slew of expensive components designed to allow the race engine to rev to the moon to achieve the elevated specific output. The downside of an elevated specific output is that the combination of compression, cam timing and head flow would certainly decrease driveability (an 800hp 460 would definitely be considered a race-only engine). Simply put, the smaller the engine, the wilder the combination required to reach a given power output.
One way around the driveability (or race-only) issue is to increase displacement. Increasing the displacement reduces the specific output required to reach a given power output. If we retain our goal of 800 hp but increase the displacement of our engine to 557 ci, we see that we have reduced the specific output to just 1.436 hp per cubic inch (the equivalent of a 433hp 302). It is not only much easier to produce 800 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. An 800hp 460 will likely make peak power at or near 7,800 rpm, while the same power output from this 557 came at just 6,800 rpm. The 557-inch stroker kit will not cost any more (and likely less) than the rotating assembly required for building a dedicated 800hp 460 motor, but it will be more than pulling a used 460 from the wrecking yard.