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496ci Big-Block Makes 1,144 hp on 11.2 psi of Boost!

Multipurpose Power: We try out two different methods to add big power to a big-block

Richard Holdener Aug 29, 2017
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Big-block builds come in many shapes and sizes, or more accurately displacements, but this build offers something special. While a 496 is a common displacement, this combination was designed with more than just additional cubic inches in mind. Dedicated buildups often focus on maximizing for a single purpose. By this, we mean that naturally aspirated engines are built slightly different than ones built for nitrous and different yet for blower combinations. The three distinct combos often differ in things like cylinder head configurations, cam timing, and compression ratio. The cylinder head and cam needs of a nitrous engine differ from those of its naturally aspirated or supercharged brethren. Blower engines typically receive a drop in static compression, which works well under boost, but definitely gives up some off-boost power. Rather than choose a specific path, we decided to build a combination that worked well in all three configurations, essentially capable of supplying multipurpose power.

Were we going racing we might choose a dedicated path, but for street and even street/strip engines owners often change their mind about what they want. After running a naturally aspirated engine, enthusiasts start to want more. Adding more power to any combination is as easy as placing a call to the guys at NOS. No matter what engine you add it to, nitrous oxide makes a huge improvement. Any time you increase the power output by 100, 150, or even 200 (or more) horsepower you’re going to like it. The problem becomes, just like with a naturally aspirated engine, the extra power provided by the nitrous just won’t be enough after a time. Luckily, nitrous kits are adjustable so more power is easily attainable. But what if you want even more power? That’s when boost comes into play. Adding a supercharger, like a ProCharger, to your combo can yield more power, and like the nitrous is easily adjustable for even greater gains. Of course, this all assumes your engine is capable of withstanding the extra power and that the naturally aspirated combination responds well to both the nitrous and supercharger. Big assumptions.

To ensure our build responded well to both nitrous and boost we made sure the engine met two critical conditions: increased internal strength and plenty of power. Upping strength of the internal components was a no-brainer since the crank, rods, and pistons must be up to the task of withstanding the extra power production offered by nitrous or boost. This obviously necessitated forged internals. To maximize power production we assembled a combination capable of producing plenty of power even before hitting it with the NOS Cheater nitrous system or the ProCharger supercharger. The more power the engine makes in naturally aspirated trim, the more power it will make with power-adders.

The internal strength came easy as we combined a 4.25-inch, 4340 forged-steel stoker crank from Scat with a set of Bullet-series Carrillo rods and 4.31-inch, forged CP pistons. The 24cc-dome pistons produced a static compression ratio of 10.5:1, and featured 2618 alloy construction, dual-forced pin oilers, and chromoly wristpins with wire locks. The compression was high enough to help make power, but still low enough to run boost. The Bullet rods were equally stout, being manufactured from 4330 modified forgings with WMC H-11 tool steel fasteners and the set balanced to within 1.0 gram of each other.

With strength taken care of, we set our sights on power production. To help the beefy bottom end pull hard on the top end we enlisted power producers from Comp Cams, ProMaxx, and Edelbrock. With a blower in mind, we chose a suitable blower cam knowing full well it worked on both naturally aspirated and nitrous combos. The 300BR-14 featured 0.652/0.652-inch lift, a 255/262-degree duration split, and 114-degree LSA. The cam was combined with a new set of solid roller lifters, hardened pushrods, and Crane 1.73:1 (BBF) roller rockers. To provide adequate flow for the solid roller cam we installed a set of ProMaxx aluminum heads. These heads featured 340cc intake ports, a 2.30/1.88 stainless (back-cut and swirl polished) valve combo, and 122cc combustion chambers. Thanks to full CNC porting, the intake ports checked in with 412 cfm at 0.900 lift (according to their own flow testing). Having previously exceeded 800 hp with these heads on a wilder 572 stroker, we knew they were more than adequate for our “little” 496. The final of our three major power producers was the single-plane Super Victor intake from Edelbrock. To ensure our stroker had plenty of air and fuel the intake was combined with a Holley 1050 Ultra Dominator carburetor.

While we had the major components taken care of, we added the equally important subsystems to the stroker to make it run, including a billet distributor from MSD, an SFI-approved damper and fabricated valve covers from Speedmaster, and a rock-solid oiling system. The ProMaxx aluminum heads were secured using a set of ARP head bolts and MLS head gaskets from Fel-Pro. We made sure to have the surface finish on the block and heads correct for use with the MLS gaskets.

After a few break-in cycles using Lucas break-in oil we started tuning the big-block combo. Dialing in the Holley carb took all of one jet change, it was nearly perfect right out of the box. After running timing sweeps up to 40 degrees (it ran best at 37 degrees), the big-block pumped out 677 hp at 6,400 rpm and 591 lb-ft of torque at 5,300 rpm. We were plenty happy with the power output, especially since we didn’t go whole hog on a wild cam profile or jack up the static compression. The big-block stroker was plenty stout in naturally aspirated form but things were about to get even more impressive.

The first of our power-adders was an NOS Cheater nitrous system. The carbureted plate system featured a nitrous plate to deliver the nitrous and fuel, a pair of solenoids to deliver said components to the plate, and adjustable jetting to determine just how much to supply. The kit also featured a 10-pound bottle, arming and activation switches, and all the necessary mounting hardware and lines. We removed the carburetor and quickly installed the nitrous kit. After installation of the jetting to provide an additional 150 hp, we filled and heated the bottle (the bottle is shipped empty) then hooked up the requisite fuel lines. With everything ready, we ran the big-block once again and were rewarded with 859 hp and 769 lb-ft of torque. With careful tuning, the 150hp shot improved the power output by 182 hp. We made sure to dial the total timing back per the instructions, but went just 4 degrees instead of the recommended 6. Adding a splash of 100-octane race fuel to the 91-octane unleaded gave us the extra margin of safety.

It was then time to subject the big-block to some boost. In this case, boost came from a ProCharger F-1A-94 supercharger. According to ProCharger, the ultra-efficient centrifugal supercharger was capable of supporting 1,200 hp, but having already exceeded 1,260 hp with the unit on a 427 LSX, we think their ratings were a tad conservative. Regardless, it was more supercharger than we would need for our big-block. In addition to the F-1A-94, ProCharger also supplied an air-to-water intercooler. Though we ran just over 11 psi on the 496, an intercooler is always good idea, especially after we ditched the carburetor in favor of fuel injection. The carb acts as an intercooler, but since we adopted port fuel injection, the benefits of fuel cooling were all but lost. The kit was installed with the supplied crank and 4.5-inch blower pulley, the largest blower pulley of the five they supplied (meaning the lowest boost level). After installation of the converted Edelbrock 454-R intake, Holley EFI management system, and Wilson elbow (with 105mm throttle body), the supercharged 496 pumped out 1,144 hp at 6,500 rpm and 925 lb-ft of torque (also at 6,500 rpm). That we just reached the torque peak and the horsepower was still climbing by over 20 hp per 100 rpm it was a clear indication that there was plenty more power to be had from our multipurpose big-block.

Big Block 496 Nos Procharger Dyno Test F1a94 002 2/29

1. The Gen V four-bolt block was machined to accept a Scat 4.25-inch forged stroker crank.

Big Block 496 Nos Procharger Dyno Test F1a94 003 3/29

2. The Scat crank was teamed with a set of Bullet-series Carrillo rods and matching forged CP pistons.

Big Block 496 Nos Procharger Dyno Test F1a94 004 4/29

3. The forged crank, rods, and pistons combined with the four-bolt factory block to produce a solid short-block capable of withstanding your choice of power-adder.

Big Block 496 Nos Procharger Dyno Test F1a94 005 5/29

4. Rather than go ultra-low or ultra-high compression, we chose small-dome pistons with generous valve reliefs from the CP catalog. The added compression (over a typical blower combo) offered extra power when off boost and worked equally well with the nitrous.

Big Block 496 Nos Procharger Dyno Test F1a94 006 6/29

5. Because we knew it worked so well on past blower builds (NA and nitrous, too), we installed a 300BR-14 blower cam from Comp Cams. The solid roller grind offered 0.652/0.652-inch lift, a 255/262-degree duration split (at .050), and 114-degree LSA. Comp also supplied the necessary roller lifters.

Big Block 496 Nos Procharger Dyno Test F1a94 007 7/29

6. To dial in the cam timing, we installed an adjustable double-roller timing chain. Note the nylon cam button necessary to limit thrust movement with the roller cam.

Big Block 496 Nos Procharger Dyno Test F1a94 008 8/29

7. The bottom end was completed with a high-volume oil pump, HD intermediate shaft, and a pickup from Milodon that would match up with the pan we chose. The pump was secured with an ARP oil-pump stud.

Big Block 496 Nos Procharger Dyno Test F1a94 009 9/29

8. With a healthy cam and extra displacement, the stroker needed a good set of heads. We actually went a little overkill with these CNC-ported, 340cc heads from ProMaxx. We used them previously on a 572 that exceeded 800 hp, so we knew the 400-cfm intake ports would easily support our 496.

Big Block 496 Nos Procharger Dyno Test F1a94 010 10/29

9. The 121cc combustion chambers worked with our small-dome pistons to produce a static compression ratio of 10.5:1. The aluminum heads also featured a 2.30/1.88 stainless-steel valve package.

Big Block 496 Nos Procharger Dyno Test F1a94 011 11/29

10. To ensure adequate sealing with our power-adders we enlisted the aid of Fel-Pro gaskets. These MLS head gaskets are plenty stout. Just make sure the head and block deck surfaces are finished properly for them.

Big Block 496 Nos Procharger Dyno Test F1a94 012 12/29

11. The ProMaxx heads came equipped with a triple spring package designed to support roller cams up to 0.900-inch lift. Actuating the valves was a set of 1.73:1 (BBF) Crane Gold roller rockers.

Big Block 496 Nos Procharger Dyno Test F1a94 013 13/29

12. Edelbrock stepped up with this single-plane Super Victor intake designed for use with a 4500-series carburetor.

Big Block 496 Nos Procharger Dyno Test F1a94 014 14/29

13. The Edelbrock Super Victor was topped with a Holley 1050 Ultra Dominator. The three-circuit carb allowed us to properly dial in the air/fuel mixture of the carbureted big-block.

Big Block 496 Nos Procharger Dyno Test F1a94 015 15/29

14. After adding a Speedmaster neutral damper and fabricated valve covers, we treated the new engine to a pair of break-in cycles. Once dialed in, we were rewarded with peak numbers of 677 hp at 6,400 rpm and 591 lb-ft of torque at 5,300 rpm.

Big Block 496 Nos Procharger Dyno Test F1a94 016 16/29

15. The NOS Cheater nitrous system included everything we needed to increase the power output of our big-block by as much as 250 horsepower.

Big Block 496 Nos Procharger Dyno Test F1a94 017 17/29

16. Off came the Holley Dominator to make room for longer studs to facilitate installation of the nitrous plate on the Edelbrock intake.

Big Block 496 Nos Procharger Dyno Test F1a94 018 18/29

17. The dual spray bars allowed injection of both nitrous and fuel into the engine.

Big Block 496 Nos Procharger Dyno Test F1a94 019 19/29

18. The nitrous and fuel were supplied by solenoids. The amount of fuel and nitrous supplied by the solenoids was determined by jet sizing. We installed jetting to provide an additional 150 hp.

Big Block 496 Nos Procharger Dyno Test F1a94 020 20/29

19. We made sure to maximize the nitrous flow by properly heating the bottle prior to injection. The optimum temperature of 92 degrees produced a bottle pressure of over 900 psi.

Big Block 496 Nos Procharger Dyno Test F1a94 021 21/29

20. Running the dual-purpose 496 with the first of our two power-adders the nitrous-injected stroker produced 859 hp at 6,300 rpm and 769 lb-ft of torque at 5,700 rpm. The NOS kit added some serious power to our big-block.

Big Block 496 Nos Procharger Dyno Test F1a94 022 22/29

21. After the success with the NOS kit, off came the carbureted induction system to make room for fuel injection. Using an Edelbrock 454-R intake converted for EFI use, we added this Wilson billet elbow and 105mm throttle body.

Big Block 496 Nos Procharger Dyno Test F1a94 023 23/29

22. Feeding boost to our big-block was an F-1A-94 centrifugal supercharger from ProCharger. The ultra-efficient supercharger was capable of easily supporting over 1,200 hp on the right application.

Big Block 496 Nos Procharger Dyno Test F1a94 024 24/29

23. To allow us to dial in the boost on the big-block, ProCharger supplied a variety of different blower pulley sizes to work with their supplied 10-rib crank pulley.

Big Block 496 Nos Procharger Dyno Test F1a94 025 25/29

24. Our testing was run with the largest (4.50-inch) of the supplied blower pulleys, meaning there was plenty of boost left in reserve.

Big Block 496 Nos Procharger Dyno Test F1a94 026 26/29

25. To keep things cool, ProCharger supplied this air-to-water intercooler. Even at just 11 psi (with dyno water), the intercooler dropped the charge temps by over 80 degrees.

Big Block 496 Nos Procharger Dyno Test F1a94 027 27/29

26. Run with the ProCharger F-1A-94 pumping out a maximum of 11.2 psi, the supercharged big-block produced 1,144 hp at 6,500 rpm and the numbers hadn’t even peaked yet! Imagine ripping down the street with that much power under the hood.

Big Block 496 Nos Procharger Dyno Test F1a94 028 28/29

27. The first thing you might notice on the graph is the huge gain in power offered by the NOS nitrous kit, but you might do well to take a step back and look at the power output of the 496 before we hit the button. Run sans nitrous, the all-motor 496 produced 677 hp and 591 lb-ft of torque. Who wouldn’t love to have that much power in their Chevy? Thanks to the use of forged Carrillo rods and CP pistons, the plenty-powerful 496 was more than ready for a healthy shot of go juice. After installation of the NOS Cheater system, the peak numbers jumped to 859 hp and 769 lb-ft of torque. There was another 100 hp or so left in the Cheater kit but we think you’ll have no trouble getting your point across with an 850hp, nitrous-injected big-block.

Big Block 496 Nos Procharger Dyno Test F1a94 029 29/29

28. To further illustrate the strength of the forged internals and overall balance of our big-block build we subjected the beast to some boost! Our big-block build included two critical elements: internal strength and plenty of power production in naturally aspirated trim. The more power the engine makes on its own the more power it will make under boost. Case in point, we produced 1,144 hp after adding the F-1A-94 ProCharger kit at just 11.2 psi. With each psi of boost worth roughly 47 hp on our big-block, there was maybe an extra 200 horsepower (or so) to be had from the ProCharger, but maxing out the supercharger was not the goal of the build.

Photography By Richard Holdener

Sources

Comp Cams
Memphis, TN 38118
901-795-2400
http://www.compcams.com
CP Pistons/Carillo Rods
949-567-9000
www.cp-carrillo.com
ProCharger
Lenexa, KS 66215
913-338-2886
www.procharger.com
Scat Enterprises
310-370-5501
scatenterprises.com
Fel-Pro
Southfield, MI 48034
800-325-8886
www.felpro-only.com
Edelbrock
Torrance, CA 90503
310-781-2222
www.edelbrock.com
MSD
El Paso,
915-857-5200
MSDPerformance.com
ARP
Ventura, CA 93003
800-826-3045
arpdiesel.com
Speedmaster
909-605-1123
www.speedmaster79.com
Holley/Hooker/NOS
270-782-2900
www.holley.com
ProMaxx Performance
800-235-4323
promaxxperformance.com

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