How much horsepower is a 350 big block?
There is no standard “350 big-block” horsepower figure. The 350 cubic-inch Chevrolet engine is part of the small-block family, and horsepower varies widely by model, year and configuration. In stock form, you’ll typically see roughly 250 to 370 horsepower, with emissions-era changes and net-rating adjustments often producing lower numbers. High-performance variants and modern EFI setups can push well beyond that, especially in crate engines or heavily modified builds.
Clarifying the terminology: big-block vs. small-block
What people often stumble over is the difference between Chevrolet’s big-block and small-block families. The “350” designation refers to displacement (350 cubic inches) and is associated with the small-block family. Chevrolet did not produce a standard, factory “350 big-block.” If you see someone calling a 350 a big-block, it’s usually a mislabel or a reference to a different engine lineage with the same displacement. The exact horsepower depends on the engine’s year, model, and whether the rating is gross (older practice) or net (modern practice).
Why ratings can be confusing
Horsepower numbers have changed over time due to evolving rating methods (gross vs. net) and the advent of emissions controls. A 350 small-block rated gross in the late 1960s might show a higher figure than the same engine’s net rating in the 1970s or 1980s. For an apples-to-apples comparison, you need to know the rating method and the specific configuration.
Stock horsepower ranges for the 350 small-block (Chevrolet)
Before listing, it’s helpful to note that exact figures vary by year, model, and whether the rating is gross or net. The ranges below provide a broad sense of what you might expect across the 350 small-block family.
- Early-to-mid era (roughly 1960s to early 1970s): about 250–360 hp in higher-performance configurations; base 350s typically closer to the 250–300 hp range.
- Emissions-era and post-1971 ratings: net horsepower generally lower, commonly in the 150–300 hp range depending on tuning, exhaust, and emissions equipment.
- Late-1990s onward (fuel-injected and modernized engines): commonly around 275–320 hp in many passenger-car applications, with higher-output variants approaching 340–350 hp in select setups.
Note: These figures are approximate and reflect typical factory configurations. For an exact number, consult the specific model-year brochure, the engine code, or the factory service manual for the car in question.
How to verify horsepower for a specific engine
To determine the exact horsepower of a given 350 small-block, use these steps. This helps when buying a car, evaluating a project, or identifying a crate engine.
- Locate the engine code or stamping on the block and pull the vehicle’s VIN to confirm original equipment.
- Check the factory service manual or original Chevrolet literature for that year and model, and note whether the rating is gross or net.
- Compare with official brochures or GM’s RPO (Regular Production Option) sheets for the car; remember that different trims used different induction, heads, and compression.
- Consider whether the engine uses carburetion or modern fuel injection, as that affects the horsepower figure and its torque delivery.
If you’re evaluating a crate engine or a heavily modified build, horsepower can vary widely—from stock ratings to well over 400 hp, and in some extreme builds, 500+ hp or more with forced induction.
Summary
The expression “350 big-block” does not correspond to a standard Chevrolet engine. The 350 cu in engine is a small-block, and its horsepower depends strongly on year, model, and configuration. In factory form, expect roughly 250–360 hp for many 350 small-blocks in older, performance-oriented configurations, with net ratings typically lower during the emissions era. Modern or modified setups can exceed 350 hp easily. For a precise figure, identify the exact engine code, model year, and rating method, and consult the original manufacturer’s documentation.
