What is the horsepower rating for a 420cc Briggs and Stratton engine?

When it comes to engines, particularly within a reputable brand like Briggs & Stratton, it is not uncommon to want to know how cc's relate to horsepower. The 420cc Briggs & Stratton is one of the most desirable engine sizes typically included with pressure washers and riding mowers, making it very popular. The reason we want to know the horsepower numbers is to assess engine capabilities and, therefore, proper engine maintenance!

Horsepower rating for a 420cc Briggs and Stratton engine

Understanding CC and Horsepower Conversion

Cubic centimeters (cc) measure the engine displacement, or the total volume of the cylinders in which fuel and air are burned. Horsepower (HP), on the other hand, measures the engine’s power output — how much work it can perform over time. For small engines like Briggs & Stratton’s, the general conversion formula is:

  • HP = CC ÷ 32.2 (approximation)

Using this calculation, a 420cc Briggs & Stratton engine produces around 13 HP. However, depending on design factors, tuning, and load conditions, the actual value may range between 12.5 and 15 HP.

How 420cc Engines Are Used

The 420cc Briggs & Stratton engine is designed for both residential and commercial-grade equipment. Its strong torque, easy-start system, and durable components make it ideal for:

  1. Large riding mowers
  2. Heavy-duty pressure washers
  3. Power generators
  4. Tillers and trenchers

These engines deliver consistent performance under demanding conditions and are well known for their long service life when properly maintained.

Briggs & Stratton 420cc Engine Specifications

Specification Details
Engine Displacement 420cc
Horsepower Range 12.5 HP – 15 HP (average ~13 HP)
Torque Up to 20 lb-ft
Fuel Type Unleaded Gasoline
Applications Generators, Mowers, Tillers, Washers

Performance and Maintenance Tips

To get the best results from your 420cc Briggs & Stratton engine, remember to:

  • Check and replace oil every 25 hours of use.
  • Keep air filters clean to maintain steady airflow.
  • Replace spark plugs at the beginning of each season.
  • Use only genuine Briggs & Stratton replacement parts to preserve efficiency and lifespan.

Find Genuine 420cc Briggs & Stratton Parts

Whether you need a replacement carburetor, oil filter, or spark plug, using OEM Briggs & Stratton parts ensures your engine continues to deliver the performance it was designed for. Please explore our complete Briggs & Stratton parts catalog to find the exact components for your 420cc model and keep your equipment running at peak power.

Nov 3rd 2025 Ivan Lozano Llanos

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