Some time back, we took BluePrint Engines up on their offer to test a 540-inch big-block designed for power-adder use. What do we mean by that? Well, since power-adders like nitrous oxide, turbos, and blowers are so popular, builders like BluePrint have assembled crate engines designed specifically for use with power-adders. A year or so back, we subjected the 540 big-block (dubbed the Mad Adder) to all manner of power-adders, including nitrous oxide, two different types of superchargers, and finally a pair of turbos. While we might not go quite as hog wild on the small-block offering, we do have plans to run a number of different power-adders on the 383, starting with our old friend, nitrous oxide! Since we named the 540-inch big-block the Mad Adder, we decided to call this smaller 383, the Mad Adder Jr.
Before we get to the dyno test, we need to take a look at what went into making the power-adder version of the 383 stroker from BluePrint Engines. Right off the bat, the 383 (PN BP38317CT1) offered strength in the form of BluePrint’s own cast-iron, four-bolt block. The block was combined with a forged rotating assembly that included a 3.75-inch stroker crank, 5.70-inch I-beam connecting rods, forged pistons, Hastings molly 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 cam supplied with the 383 offered a 0.536/0.555-inch lift split, a 224/236-degree duration split, and 113-degree LSA. The heads, also produced by BluePrint (PN 138-H8002K), have 195cc intake runners, 64cc combustion chambers, and 2.02/1.60-inch valves. The supplied long-block also came with a 30-month, 50,000-mile warranty.
BluePrint rated the 383 stroker at 445 hp and 463 lb-ft of torque. Before we could test their power rating, we had to complete the long-block. The aluminum-headed 383 was topped off with an induction system that included an Edelbrock RPM Air-Gap intake and Holley 650 Ultra XP carburetor. While the carb supplied fuel, the engine still needed some spark, so we added an MSD billet distributor. The information supplied with the crate engine included the ignition timing specifications, so we set the distributor to provide a total of 34 degrees (though we tried other timing values to no avail). The engine was configured with an externally balanced flywheel, but came with a neutral-balance damper. After filing the crankcase with 30W break-in oil from Lucas, and running a few break-in cycles, we were able to run the engine in anger. After swapping a few jets and playing with the timing, we were rewarded with peak numbers of 446 hp and 457 lb-ft of torque. A little more tuning could get us to the torque rating supplied by BluePrint, so they obviously know what these things make!
After our break-in and dyno test in naturally aspirated trim, we were free to start with the first of our power-adders. For round one, we chose nitrous oxide in the form of a Zex Perimeter Plate wet system. The Zex plate featured 12 equally spaced dispersion holes designed to equalize distribution of the nitrous and fuel to all cylinders. Like most systems, the Zex kit was adjustable (up to 300 hp) using the supplied jetting. We opted to run on pump gas for this test and chose our jetting accordingly. Starting out small, we tried a 75hp shot then followed that up with a 100hp shot. We made sure to heat the bottle to produce over 900 psi of bottle pressure and dial in the fuel pressure to 6 psi feeding the fuel solenoid. We dialed back the ignition timing according to the instructions and dropped timing by 3 degrees for the 75hp shot. In truth, we have run this power level with no timing retard using 91-octane pump gas, but we decided to see how it ran per the instructions. Equipped with the 75hp jetting, the power output jumped to 516 hp and 546 lb-ft of torque. The mixture was a tad on the rich side so we dialed back the fuel pressure on the next test with 100hp jetting. Run with the 100hp jets, the power jumped to 572 hp and 607 lb-ft of torque. There’s nothing like adding 126 hp with 100hp jetting. The Mad Adder Jr. is officially off and running!
1. If (like us) you’re planning on nitrous, a blower, or turbo, what better way to start than with a stroker enginer designed specifically for power-adders?
2. The power-adder ready 383 stroker crate engine from BluePrint Engines offered a number of desirable features, including low compression along with forged pistons, rods, and crank. Coupled with a super strong four-bolt main block and high-flowing aluminum heads, and it makes for a package ready for boost or a shot of nitrous.
3. Since the 383 was supplied as a long-block, we topped it with an Edelbrock Performer RPM Air-Gap intake. Note also the MSD distributor used to ensure a hot spark with our power-adders.
4. Initially, we installed a Holley 650 Ultra XP carb, then stepped up to a larger 750 version. The larger carb offered no power gains over the smaller 650 model.
5. Rated at 445 hp from BluePrint, our engine produced 446 hp and 457 lb-ft of torque. Obviously, they know what these engines make from testing on their own dyno. To help the 383 exhale we went with a set of 1 3/4-inch long-tube headers with collector extensions.
6. After establishing a baseline, we tore in to the new Perimeter Plate nitrous kit from Zex.
7. The plate featured 12 equally spaced points of dispersion designed to equalize distribution to all cylinders.
8. The power output of the kit was adjustable up to 300 hp using the supplied nitrous and fuel jets. We ran jetting for both 75 and 100 horsepower.
9. The plate was installed onto the awaiting dual-plane manifold.
10. It is important to tune the fuel pressure feeding the nitrous system. The dyno featured a dedicated fuel supply, which we adjusted to 6 psi per the instructions.
11. The bottle pressure was also important, as it determined the flow of nitrous to the engine. We relied on this bottle heater to optimize the bottle pressure.
12. To ensure the bottle had adequate pressure, we installed a pressure gauge in the nitrous line. Optimum nitrous flow came with 900 psi of bottle pressure.
13. What we liked about the power-adder ready 383 from BluePrint was that we didn’t have to worry about whether the stroker was stout enough to handle the shots of nitrous. Equipped with a four-bolt block and forged internals, the stroker was primed and ready for action. Rated at 445 hp, the nearly 9.0:1 combination produced 446 and 457 lb-ft of torque with the Edelbrock Performer RPM Air-Gap intake and Holley 750 carb. After installation of the Zex Perimeter Plate nitrous system, the power output jumped to 516 hp with 75hp jetting and 572 hp with 100hp jetting. Torque production exceeded 600 lb-ft with the 100hp jets. Not bad for a pump-gas tune! Next up will be a date with some boost.
Photography by Richard Holdener