The question of the day was a simple one. What do you do with a power-adder-ready 383 crate engine from BluePrint Engines? For us, we immediately topped off the long-block, popped it up on the dyno, and added some nitrous to the mix. With “power adder” right in the name, what else would you expect? As it turned out, the 383 stroker (PN BP38317CT1) was more than up to the task of withstanding the hit(s) from the Zex Perimeter Plate nitrous system. Running first a 75hp shot then a more powerful 100hp shot, we eventually increased the power output of the engine by 126 hp. We love it when we gain more than the rated output of the jet kit, but that was a simple matter of proper tuning. Equipped with the Zex kit, the 383 stroker was sporting no less than 572 hp. As much as we liked the idea of a 572hp small-block, you know what sounded even better? Obviously, a small-block sporting over 600 hp. The question was, how do we get it? Enter the obvious answer, boost.
When it comes to increasing the power output of just about any engine, there is nothing better than boost. Boost is the great equalizer, or more specifically the great multiplier. What do we mean? Suppose you have a 300hp small-block and want to increase the power output. If we add boost to the 300hp small-block, we can theoretically double the power output (to 600 hp) at 14.7 psi of boost. This is because the naturally aspirated engine already has 14.7 psi of atmospheric pressure on it (at least at sea level). If we double this pressure by providing 14.7 psi of boost, we can (sometimes) double the power output. This equation works for any boost level, meaning we can increase the power output by 50 percent (to 450 hp) at 7.35 psi, by 68 percent (to 504 hp) at 10 psi and triple the power output (to 900 hp) at 29.4 psi. As nice as this math formula works on paper, it does not take into account a number of variables like air/fuel ratio and timing, discharge temperature, or parasitic losses associated with spinning a supercharger. It does, however, provide an estimate on what to expect from a boosted application if you know the naturally aspirated power output.
In the case of our 383 stroker from BluePrint Engines, we knew exactly what to expect from the naturally aspirated combination, as BluePrint had taken the liberty of testing their combinations. This 383 was rated by BluePrint to produce 445 horsepower. The 383 was supplied in long-block form, meaning it lacked an induction system and distributor. The stroker assembly included forged internals stuffed inside BluePrint’s own four-bolt block. The forged pistons provided a static compression ratio of 8.9:1 when combined with 64cc chambers in the 195cc, as-cast aluminum heads. The 383 also featured a healthy hydraulic roller cam profile that offered a 0.536/0.555-inch lift split, a 224/236-degree duration split, and 113-degree LSA. The long-block was completed for dyno use with a dual-plane, Edelbrock Performer RPM Air-Gap intake and Holley 650 Ultra XP carburetor. Since our blower engine required a hot spark, we chose an MSD billet distributor combined with a 6AL ignition amplifier. Run in this condition with a set of 1.75-inch headers, the 383 produced 446 hp and 457 lb-ft of torque. With our baseline established, it was time to get the small-block all torqued up with some boost.
And this time around, a TorqStorm, centrifugal supercharger kit would handle the atmospheric compression. We went with a driver-side, natural finish unit, but TorqStorm also has a passenger-side mount kit as well as black and polished finish options. The units are made in-house on their CNC mills and lathes. They cut their own billet impellers and all of the units include a bung if you want to do a water/methanol injection setup. The whole kit, including everything from the carb hat to the crank pulley is well under $3,000. Add in a limited lifetime warranty and it makes for a lot of wallet-friendly performance.
1. The power-adder-ready 383 long-block from BluePrint Engines (PN BP38317CT1) was filled with a forged rotating assembly that included a 3.75-inch stroker crank, 5.70-inch I-beam connecting rods, forged pistons, Hastings moly rings, heavy-duty timing set, and a high-volume Melling oil pump. To keep the 383 boost and nitrous friendly, the engine featured a static compression of 8.9:1. That should safely allow reasonable levels of boost on pump gas, and extreme levels on race fuel. The 383 assembly also featured a hydraulic roller cam and free-flowing aluminum heads. The heads, also produced by BluePrint (PN 138-H8002K), have 195cc intake runners, 64cc combustion chambers, and 2.02/1.60-inch valves. All of that and it had a 30-month, 50,000-mile warranty.
2. We topped the long-block off with a dual-plane Edelbrock Performer RPM Air-Gap intake.
3. Feeding the Edelbrock, in naturally aspirated trim, was a Holley 650 Ultra XP carburetor. We also tried a larger 750 but the carb swap netted no power gains. Run on the dyno with an MSD distributor and long-tube headers, the naturally aspirated 383 produced 446 hp and 457 lb-ft of torque.
4. Next, we installed the 0.75-inch thick CNC-machined mounting bracket for the TorqStorm supercharger. The bracket bolted to the head using the supplied hardware.
5. With the mounting bracket in place, we secured the centrifugal supercharger to the bracket. The TorqStorm blower was sized perfectly for a low-boost, non-intercooled street/strip application. Capable of supporting over 700 hp, we knew it was right in the sweet spot for our stroker. Bolting on the blower was a simple matter, as it required no oil feed or drain back lines.
6. The centrifugal supercharger was equipped with a high-speed impeller and can be likened to a crank-driven turbocharger. The housing and cover are both machined from billet 6061 aluminum and the V-band clamping system allows the compressor to be clocked in any position relative to the housing.
7. TorqStorm also supplied a 7.75-inch (8-rib) crank pulley to drive the supercharger.
8. The supercharger kit featured an adjustable tensioner used to eliminate belt slippage. Internally, the unit uses a proprietary ceramic bearing system to increase service life along with various coatings for temperature and wear control.
9. For use with the supercharger, we replaced the 650 Holley with a blow-through 850. Using jetting and adjustable (boost-referenced) power valves, we were able to dial in the air/fuel mixture on our supercharged 383.
10. For this test, we combined our 850-cfm carburetor with a matching carb bonnet.
11. The crank pulley was combined with a 3.25-inch blower pulley to produce a maximum boost pressure of 9.6 psi on our BluePrint 383.
12. The discharge tube from the supercharger to the carb bonnet was equipped with a blow-off valve to eliminate the pressure buildup that occurs during cruise and the spikes that accompany high rpm (and boost) throttle lift-off conditions.
13. After adding the TorqStorm supercharger to the mix, the blower provided a peak boost pressure of 9.6 psi at 6,200 rpm. Blowing through the 850-cfm carburetor, the supercharged 383 produced 635 hp and 596 lb-ft of torque. That’s a nice gain of nearly 200 hp from a simple bolt-on blower. There was also a huge gain in torque all across the pull.
Photography by Richard Holdener