Table of Contents
Introduction
Introducing the latest in XB GT performance, a genuine 1978 model that has been transformed into a street‑ready powerhouse by Competition Engines. The car, originally a rare color and trim, still retains its authentic interior—quarter‑vent windows, original seat covers, dash, steering wheel, and headlining—all untouched. The owner, Glenn Huxley, was initially disappointed with the stock 750‑hp engine’s lack of power and drivability, prompting a complete overhaul that blends classic styling with modern engineering.
Engine Modifications
At the heart of the rebuild is a 408‑hydraulic roller engine, a staple of Competition Engines’ roster. The team salvaged the original ICE ignition system and a 750‑hp Holly carburetor, converting it to a dual‑entry setup with a custom fuel rail and hard‑line. A billet fuel filter and a 38‑mm transfer tube were added, mirroring the design of high‑performance carburetors like the HO or Phase Three. The result is a 567‑hp, 547‑ft‑lb torque machine that feels like a true race‑car engine without the harshness.
Performance and Drivability
Performance testing shows the car delivers smooth, linear power across the rev range. In second gear the engine responds instantly, while third and fourth gears provide effortless acceleration up to 150‑60 mph. The clutch, a center‑force unit, keeps the car from hopping or jumping, and the 35‑true‑track LSD ensures traction is never compromised. Drivers report a “dream” driving experience, with no hesitation or torque‑band surprises.
Exhaust and Sound
Complementing the powertrain is a new exhaust system that retains the iconic GT square tip. Competition Engines offers 2½‑inch and 3‑inch wide‑band options, both engineered to match the engine’s airflow demands. The result is a deep, throaty tone that still feels natural on the street, rather than a loud, aggressive growl typical of race‑ready setups.
Real‑World Driving Experience
During a test drive, the car’s handling was praised for its balance and predictability. The driver could comfortably navigate corners in second gear, with the engine delivering enough torque to maintain speed without over‑revving. Even at higher speeds, the car remained stable, and the throttle response was described as “no jerk” and “smooth as a whistle.”
Comparison to Original
Compared to the original XB GT, the upgraded build offers significantly more horsepower and torque while preserving the vehicle’s classic look. The original engine’s 750‑hp rating was underwhelming for a modern driver, whereas the new 567‑hp configuration provides a more engaging and usable powerband for everyday use.
Technical Highlights
Key technical highlights include the use of a 408‑hydraulic roller, dual‑entry carburetor, custom fuel rail, billet filter, and a 35‑true‑track LSD. The engine’s paint was matched to the original color, and no extra holes were drilled, keeping the car’s originality intact. The clutch and flywheel were upgraded to handle the increased power without compromising reliability.
Customer Perspective
Glenn Huxley, the owner, expressed enthusiasm about the final product, noting that the car “drives like a dream” and that the performance upgrades have made it a joy to drive. He also highlighted that the vehicle is not a race car but a street‑ready machine that can be enjoyed in everyday settings.
Future Outlook
Looking ahead, Competition Engines plans to continue refining their hydraulic roller packages, aiming to balance power, drivability, and reliability for a broader range of classic cars. Future builds may incorporate electronic fuel injection or hybrid powertrains to further enhance performance while maintaining the nostalgic feel.
Conclusion
In conclusion, the XB GT rebuild demonstrates how classic cars can be revitalized with modern engineering without sacrificing authenticity. The combination of a powerful yet smooth engine, a well‑designed exhaust, and a carefully tuned drivetrain results in a vehicle that feels both nostalgic and exhilarating. For enthusiasts looking to breathe new life into a vintage model, this project serves as a benchmark for quality, performance, and respect for the original design.