The 1999 Firebird offered two engine options: a 3.8-liter V6 for the base cars and a 5.7-liter LS1 V8 for the performance-oriented Trans Am and Formula models.
Engine options for 1999 Firebird
The list below summarizes the two powertrains that could be found in the 1999 Firebird lineup.
- 3.8-liter V6 (3800 Series II) — An overhead-valve V6 that produced roughly 200 horsepower and about 230–240 lb-ft of torque. Transmission choices typically included a 5-speed manual or a 4-speed automatic, depending on the model and option package.
- 5.7-liter LS1 V8 — A modern small-block V8 delivering approximately 305 horsepower (SAE net) with torque around 325 lb-ft in many configurations; performance variants could approach higher output figures depending on specific options and year. It was paired with either a 6-speed manual or a 4-speed automatic (4L60-E).
In context, the V6 powered the standard Firebird, while the V8 was reserved for the higher-performance trims such as the Formula and Trans Am (including the WS6-equipped versions in some years).
Performance variants and packaging
Notable performance packages included the WS6-equipped Trans Am, which featured suspension and handling upgrades and typically aligned with the LS1's horsepower in the 305–320 hp range depending on the equipment and year. The standard Formula and base Trans Am could share the LS1 engine, with output variations tied to configuration, exhaust, and gearing. The base Firebird remained the V6-powered option for customers prioritizing daily drivability and fuel economy.
In short, the 1999 Firebird offered two engines across the lineup: a 3.8-liter V6 for the base models and a 5.7-liter LS1 V8 for the performance-focused variants, with transmission choices that complemented each powertrain.
Summary
The 1999 Firebird's engine lineup was concise and focused: a 3.8L V6 for everyday driving and a 5.7L LS1 V8 for performance-minded buyers, available with either a manual or automatic transmission depending on model and package.