The Pontiac Fiero had the styling and layout to be a serious sports car, but its factory engines limited its performance potential. Now, a revived 1986 Fiero from Turnin Rust is running a Chevy 5.7-liter small-block V8, giving the mid-engine, rear-wheel-drive car substantially more muscle.
The Fiero’s Untapped Performance Potential
Among the cars produced under the General Motors umbrella, the Pontiac Fiero was one that never appeared to reach its full potential. Its distinctive wedge-shaped design, mid-engine configuration and rear-wheel-drive layout gave it the foundation for a stronger performance identity.
The Fiero could have taken its fight further against the Toyota MR2, but Pontiac produced the model only from 1983 to 1988.
Despite its performance-oriented characteristics, the Fiero initially used a 2.5-liter inline-four. The engine reflected Pontiac’s positioning of the car as an economical commuter while the company faced pressure to improve fleet fuel economy.
For 1985, Pontiac added a 2.8-liter V6 producing 140 hp, more than 40 hp above the base engine. However, the Fiero was never offered with a V8 from the factory.
A V8 could have delivered substantially more torque and quicker acceleration, although it also could have brought worse fuel consumption and greater demands on the drivetrain. A sufficiently powerful version could also have threatened the Chevrolet Corvette’s position within GM.
A V8 Fiero Built by Enthusiasts
Instead of waiting for Pontiac to build a V8-powered Fiero, some enthusiasts took on the project themselves. Turnin Rust was among them, reviving a 1986 model that had been sitting for years.
This particular Fiero already had a “Hot Rod 350,” Chevrolet’s 5.7-liter small-block V8. According to the previous owner, the engine had been running well before it suddenly failed.
An inspection by the Turnin Rust team found catastrophic internal damage, including a damaged connecting rod. The engine was considered unsalvageable and was replaced with another 350 supplied by a friend.
The replacement engine received an LT4 Hot Cam and aluminum heads. The team also transferred the oil pan from the failed V8 because the replacement engine’s pan had sustained impact damage.
Transmission Remains the Weakest Link
The V8 was paired with a 3-speed TH125C automatic transmission. Turnin Rust described the transmission as the “weakest link,” citing concerns over whether it could handle the V8’s output.
The setup uses an adapter plate along with a high-stall torque converter rated at 2,300–2,500 rpm. The combination was selected to better suit the engine’s camshaft.
The Fiero also received secondhand aftermarket suspension components, giving the car a lower and sportier stance.
How the V8 Fiero Performed
Whether the TH125C transmission can withstand the V8’s output over time remains uncertain. During the initial test drive, however, the Pontiac Fiero appeared to run well and pulled hard on the street.
The project highlights the performance potential that enthusiasts saw in the Fiero despite the engines Pontiac offered from the factory. It also provides another look at a compact sports car from an era when two-door models occupied a more visible place in the automotive landscape.
Today, compact two-door sports cars represent a smaller niche, with models such as the Mazda MX-5 and Toyota GR86 among those still occupying it, while crossovers and SUVs dominate much of the market. As electrification continues to change the automotive formula, the future of this segment remains uncertain, leaving nameplates such as the Pontiac Fiero as reminders of an earlier era.
