Chris Holbrook’s 10,000-Plus RPM 1,500HP Factory X Mustang

Since its introduction as an exhibition class in 2022, NHRA’s Factory X category presented by Holley EFI has seen growth in the number of participants and in the interest from fans. For 2024, Holley EFI Factory X is finally having its first full season within the NHRA schedule. According to the NHRA, the class was formed to bridge the gap between Factory Stock Showdown and Pro Stock. The Factory X class blends the excitement of the big three auto manufacturers going head to head in door-slammer battle with supercharged engines and factory-appearing cars, plus the added difficulty of a class-mandated manual transmission makes for thrilling side-by-side racing. Chris Holbrook is campaigning his Varsity Ford-sponsored Mustang this season and has his sights set on bounties offered by ARP for a 6-second pass and JESEL valvetrain for a 200mph pass.

Images and video courtesy of Evan Smith and his REVan Evan Youtube Channel

Factory X

Holbrook is a familiar face in the NHRA and among Ford fans. He is a well-known and long-time high-performance engine builder as well as the owner of Holbrook Racing Engines, specializing in Ford powerplants. Additionally, Holbrook has an extensive history working with Ford Performance Parts, and he has plenty of drag racing experience having competed in Pro Stock and Factory Showdown. His Factory X entry is an S650 Ford Mustang body on a Jerry Bickel Race Cars chassis. Factory X cars use a four-link rear suspension setup and the chassis are built to SFI 25.1, 25.2, and 25.3 specifications depending on the weight of the car. The car sits on Lamb coilover struts in the front and Menscer Motorsports coilovers in the rear. Rolling stock consists of Weld Racing wheels with double beadlocks in the rear with Hoosier 33×10.5-inch slicks providing traction. Helping to slow the car down and save weight are Lamb carbon fiber brakes. Unlike the Factory Showdown cars’ 3,500-plus pound minimum weight, Factory X cars are much lighter at 2,600 pounds.

In Factory X teams are allowed to run 2019-model-year and newer cars from the big three auto manufacturers. The three models of cars currently allowed are the Chevrolet COPO Camaro, Dodge Challenger Scat Pack, and the Ford Mustang Cobra Jet. All three vehicles are powered by supercharged engine combinations, with the Ford Mustang entry utilizing the Cobra Jet’s 302 cubic-inch engine and a 3.0-liter Whipple supercharger.

Holbrook builds his own engines at his Holbrook Racing Engines facility. Although the class limits things like maximum camshaft lift and cylinder head modifications, he says the engines produce between 1,400 and 1,500 horsepower. One item that is allowed to be changed depending on weather and track conditions is the blower pulley. Typically the Whipple supercharger will make approximately 13 pounds of boost with a healthy diet of VP Racing Fuels C16 race gas being fed from a Waterman Racing fuel pump. According to Holbrook, the little Ford engine will rev as high as 11,000 RPM but the Factory X class has a limit of 10,200 RPM, resulting in Holbrook shifting his car at a screaming 10,150 RPM. Of course, a Holley EFI system controls the engine.

Aside from the factory-appearing bodies, one of the exciting and endearing aspects of Holley EFI Factory X is the requirement that every car uses a manual transmission. Holbrook’s Mustang has a Liberty Gears 5-speed clutchless manual transmission that offers near limitless options for gear ratios and is coupled to a RAM triple-disc clutch and a Bohr Racing Products bell housing.

Factory X

The Holley EFI Factory X class is already entertaining to watch, and Holbrook believes the class will only get quicker. He has run as quick as 7.19 seconds in the quarter mile and as fast as 193mph. According to Holbrook, he expects the class to settle into the 6.80- to 6.90-second range with speeds over 200mph. As the class continues to gain support and interest from racers and fans alike, could it eventually overtake the Pro Stock category? Only time will tell, and we look forward to seeing what the future holds for NHRA Holley EFI Factory X.

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Jeremy Nichols

Jeremy loves to go fast, whether that's on two wheels, four wheels, or boating. With a willingness to compete at almost anything, Jeremy shoots competition long-range rifles matches and races road bicycles and enjoys building vehicles for people.
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