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The Demon Engines Low-Buck 454 Engine Build Part III

For The Last Installment, We Add A Little Boost To...

By Richard Holdener, Photography by Richard Holdener

Our previous two adventures with the Demon Low-Buck 454 were plenty successful. Part one demonstrated that the 400hp rating of the $2,650 Demon big-block was (if anything) a tad stingy, as the cost-conscience combo produced 445 hp and 542 lb-ft of torque. Low buck in terms of cost, the 454 nonetheless offered an impressive torque curve, bettering 500 lb-ft from 2,800 rpm to 4,600 rpm. Obviously designed for low-speed power production, the engine was an attractive alternative to the more expensive replacement and crate motors currently available. In part two, we stepped things up with a set of Profiler heads from Dr. J's, a new Comp cam, and an Edelbrock intake. The new power parts netted a jump in peak power to 564 hp, while peak torque remained unchanged at 542 lb-ft. Shifting the torque curve improved the power output by a solid 119 hp (gains were even greater higher in the rev range). More power was certainly available from this combination, but we were at a point where trade-offs in idle quality and driveability would become necessary for the additional horsepower gains.

Rather than go wilder with cam timing, compression, or even further porting the already impressive Profiler heads (strong enough to support more than 750 hp), we decided to go a different route. From the very beginning, Demon Engines swore to us that despite the use of a cast crank and stock rods (with an ARP bolt upgrade), the Low-Buck 454 would withstand some serious power levels. Having already subjected a few of its motors to nitrous and superchargers, the company was confident that these stock components would be more than up to the task of even greater cylinder pressure. Naturally, we were forced take Demon up on its offer to abuse its combo by subjecting it to some boost. Rather than call our friends at Vortech, ATI, or even Weiand for a supercharger, we decided to be trendy and go the turbo route. Big-block turbo kits are scarce, so we decided to whip up a kit ourselves. Though our intention was definitely low buck, our result was somewhat less so. We have, however, indicated cost-cutting recommendations where substitutions can be made to further reduce expenditures. Obviously, things such as the turbo and wastegate should be purchased from reputable sources, but with a welder and some tubing, you can get boost to your big-block and do so to fit just about any chassis configuration.

Turbo kits usually include all manner of elaborate plumbing, an intercooler, and some sort of management system (usually EFI), but we elected to go with a tried and true carburetor. Like the turbo itself, the custom carburetor from Carburetor Solutions Unlimited (CSU) was one of the most expensive components in the system, but it is also one of the most critical. Getting boost from a turbo to the motor is actually the easy part. Getting boost with the proper amount of fuel and timing is the difference between a successful turbo motor and a pile of broken parts. Forged crank or not, detonation will quickly (though not quietly) kill your motor. In this case, having the forged components only means it will be more expensive to replace. The lesson here is to make sure you have the proper air/fuel ratio and timing curves before running at wide-open throttle under full boost. The first component in the line of upgrades was obviously the carburetor itself. Our CSU carburetor was machined and tuned specifically for use on blow-through applications, providing precise metering under all normally aspirated and boosted conditions, including transitions. Having had such success in the past with the CSU carburetors on supercharged motors, we were eager to give this one a try on a turbocharged big-block. It is easy to tune a blow-through carburetor to either run well at full-throttle or under cruise conditions, but CSU has mastered both. CSU also supplied the required carburetor bonnet, though the ultra-low-buck approach might be to use an old air cleaner assembly.

By Richard Holdener
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