In 1990, the 5.7-liter V8—GM’s 350 cubic-inch engine—carried factory horsepower generally in the 230–245 range, depending on the model and tuning.
For context, that year’s lineup used the 5.7L across the Corvette C4, Camaro Z28/IROC-Z, and Pontiac Firebird Trans Am. Different intake tracts, exhaust systems, and emissions equipment meant small variations in the official ratings, even though the base engine remained the same displacement.
Model-by-model horsepower (1990 5.7L V8)
Here's a snapshot of the typical factory ratings reported for the main 1990 configurations that used the 5.7L V8. Values reflect the official numbers GM published for that model year.
- Chevrolet Corvette C4 (L98 5.7L V8): 240 horsepower
- Chevrolet Camaro Z28 / IROC-Z (L98 5.7L V8): 245 horsepower
- Pontiac Firebird Trans Am (L98 5.7L V8): about 230–245 horsepower, depending on trim and equipment
Note: Real-world performance can vary due to maintenance, exhaust condition, and the fact that some ratings were measured differently across model years. The figures above represent the standard factory ratings used at the time.
What influenced those numbers in 1990
The 5.7L V8 in 1990 GM cars was typically the tuned-port injection version of the 350 small-block. Emissions controls, intake and exhaust configurations, and model-specific tuning caused small shifts in the published horsepower across the lineup. The Corvette’s engine generally carried the highest rating in its family, while the sportier Camaros/Firebirds often sat at a similar or slightly higher figure depending on the exact configuration.
Bottom line
In short, a 1990 5.7L V8 produced roughly 230–245 horsepower. The Corvette's version was commonly listed at 240 hp, while the Camaro Z28/IROC-Z typically rang in around 245 hp, and the Firebird Trans Am occupied a similar band depending on the trim.
Summary
For 1990, the 5.7-liter V8 offered a narrow horsepower window of about 230–245 hp across GM’s main models, with Corvette versions traditionally at 240 hp and Camaro/Firebird variants near 245 hp. Those factory figures remain a useful benchmark for enthusiasts and collectors studying the era’s performance.