Edelbrock-Musi 555 cid Big Block Chevy - Engine Builder Magazine
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Engine of the Week

Edelbrock-Musi 555 cid Big Block Chevy

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When we last caught up with Pat Musi of Pat Musi Racing Engines in Mooresville, NC, we got the full scoop on his 959 cid nitrous engine built specifically for drag racing. In fact, since Musi moved his shop to Mooresville back in 2012 from the New Jersey area, the racer and engine building legend shifted his shop’s focus. While he used to occasionally take in some routine engine work, like a 350 Chevy or LS build, he decided eight years ago to focus strictly on drag race engines, and it’s been that way ever since.

However, Musi, in conjunction with Edelbrock, recently announced they’d be building a series of 555 cid big block Chevy engines, which are much more attainable than Musi’s typical drag race set ups for PDRA or NHRA. The engine, being called the Edelbrock-Musi 555, comes in three different configurations – AVS2 Carbureted, Pro-Flo 4 EFI, and Pro-Flo XT EFI.

Obviosuly, given both Edelbrock’s and Musi’s historical pedigrees, the engines make use of top-quality, American-made components and are assembled by hand at Musi’s state-of-the-art engine shop. Each of the three engines are designed to deliver huge performance gains on pump gas.

For the consumer, there are major advantages to dealing with a combined Edelbrock-Musi produced engine. First, the consumer gets high-quality and high-performance parts that Edelbrock has proven to deliver, along with Edelbrock’s customer service department.

Second, is the engine building and tuning expertise of Pat Musi. “Edelbrock is known for their street performance and we are proud of the track record we’ve built with our racing engines,” Musi says. “I have the first prototype 555 engine installed in my personal ‘67 Camaro, the car I started racing with. It hauls ass down the track and has been trouble free for over 10 years.”


At $15,000, the Edelbrock-Musi 555 cid carbureted engine features a 9.8˝ deck big block and Edelbrock components including CNC-ported aluminum cylinder heads, a Victor Jr. intake manifold, forged 10:1 pistons, a 4.250˝ forged steel crank, an AVS2 Series 800 CFM carburetor, a Rollin’ Thunder hydraulic roller camshaft and valvetrain, and Max-Fire ignition system.

Carbureted version

This engine delivers 676 horsepower and 649 ft.-lbs. of torque on 91 octane pump gas. The Edelbrock E-CNC cylinder heads are fully CNC ported to achieve optimal air-flow for maximum horsepower and torque in high performance street and light-duty racing applications. This engine features exhaust port exits in the stock location, which allows for the use of off-the-shelf headers.

The next level up, at $17,000, is the Edelbrock-Musi 555 Pro-Flo 4 EFI engine. This variation comes complete with Pro-Flo 4 electronic fuel injection and is assembled with intake manifold, fuel injectors, fuel rails and throttle body, ECU, handheld calibration module, high-quality billet distributor, complete harness, O2 sensor and bung, fuel hose, hardware and software.

Pro-Flo 4 EFI version

The Pro-Flo 4 EFI  can be fine-tuned with the handheld calibration module without the need for a laptop and boasts 697 horsepower and 643 ft.-lbs. of torque when tuned to run on 91-octane pump gas.

The third and top-level variation of the engine is the Edelbrock-Musi 555 Pro-Flo 4 XT EFI at $17,500. The XT is the most powerful of the three engine packages at 723 horsepower and 652 ft.-lbs. of torque, and features the Pro-Flo XT EFI.

Pro-Flo XT EFI version

The Pro-Flo XT EFI system consists of a skillfully engineered intake manifold with a unique design that delivers more horsepower and torque than a traditional single-plane intake manifold.

The Pro-Flo system includes everything needed to bolt in and go, such as fuel injectors, fuel rails, O2 sensor and bung, throttle body, ECU and handheld calibration module. The ECU is self-learning, making initial start-up and tuning a breeze.


All three versions of the 555 cid engine are competition ready, yet ultra-reliable for daily street use, and all three can be dropped in and used with standard drivelines. The standard deck block allows the engine to be installed in most cars without hood clearance issues, and the standard exhaust port location allows for the use of off-the-shelf headers.

“We see our relationship with Pat Musi and our involvement in the new Race Center as key elements to our future growth,” says Don Barry, CEO of Edelbrock. “We can’t think of a better organization to ally ourselves with than Musi Racing. Their reputation for building high performance, reliable engines is legendary.”

With every 555 engine purchase, the buyer receives a one-on-one call with Pat Musi to discuss the customer’s setup, a certificate of authenticity signed by Pat Musi, an exclusive 555 owners club decal, and of course, a powerful, new engine.


Engine of the Week is sponsored by PennGrade Motor Oil and Elring – Das Original.

If you have an engine you’d like to highlight in this series, please email Engine Builder Editor, Greg Jones at [email protected]

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