How Do I Convert Briggs & Stratton CC To Horsepower? (Do This!)

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by Upgraded Home Team

Briggs & Stratton is a gasoline engine manufacturer specializing in small engines, pressure washers, generators, and water pumps. Per industry standard, their engine specifications denote engine capacity with a “cc” (cubic centimeter) rating. This cc measurement – commonly referred to as engine displacement – indicates the cylinder capacity and volume displaced by a single revolution of an engine. In contrast, horsepower relates to a less precise measurement of general power output.

The short answer: horsepower is considered to be approximately 1/15th of its equivalent cc rating. Dividing an engine’s cc measurement by 15 will yield a rough approximation of its horsepower. To illustrate:

  • 125 / 15 = 8.3 (8 hp)
  • 140 / 15 = 9.3 (9 hp)

A lawnmower engine with a cc range between 125 and 140 will run between 8 and 9 HP (horsepower).

The longer answer: horsepower is notably influenced by less objective factors, including engine health, tuning, fuel types, and exhaust pressure. For this reason, cubic centimeter to horsepower conversions are most accurately presented as a range rather than a static value.

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What is Horsepower?

Horsepower is a very popular, historically storied term used to describe an engine’s total speed, and its ability to sustain work (sometimes known as hauling performance). It is often confused with other qualities or measurements of performance, like torque.

Torque is the pulling power of an engine, and dictates the sensation of force when a car begins to accelerate. Horsepower is a consequence of torque and engine speed (revolutions per minute, RPM), indicating how well an engine will perform continuously at peak effort. Therefore, engine size doesn’t necessarily correlate to a higher horsepower rating than smaller engines (which have higher RPM).

Horsepower can be determined through the following equation:

  • Horsepower = (T x RPM) / 5,252

    T = TorqueRPM = Revolutions Per Minute

What are Briggs & Stratton CC?

Cubic centimeters, or cc, is simply the preferred metric measurement used by Briggs & Stratton and engine manufacturers worldwide to specify engine displacement ratings. The number conveys the literal volumetric capacity of the engine’s cylinder components, and how much air or fuel can be pushed through in a single revolution of the engine.

A higher cc rating indicates a larger engine, greater cylinder volume, and more overall power potential in an engine (ex. a 4 cylinder, 2-liter engine would equate to 500cc per cylinder). Higher cc engines tend to produce more torque, resulting in more fuel burned than smaller engines.

CC may be derived through the following equation:

  • V = π/4 x (D)² x H x N

    V: cc, Volumeπ: 3.14D: Bore’s DiameterH: Stroke’s LengthN: Number of Cylinders

What’s the difference?

Horsepower acts as a function of torque and engine RPM to describe the speed and hauling sustain of an engine. In the context of racecar performance, drivers desire high torque for powerful accelerations and high RPM for efficient, sustained work at peak effort.

Peak is an operative word – horsepower is measured toward the height of an engine’s abilities. For example, if a horsepower rating was taken at 5000 RPM, it may actually produce much less horsepower at lower speeds.

Cubic centimeter measurements specify the static volume capacity of an engine. Engine displacement does not rely on factors of torque, RPM, tuning, or fuel like horsepower does. This makes cc values a more objective and reliable metric for judging engine power potential.

Why Convert Briggs & Stratton CC to Horsepower?

Knowing the engine displacement rating in cc is valuable to understanding the engine’s power output and expected fuel efficiency. A larger cc value will equate to higher power outputs, and less efficient fuel economy. But having a lot of power doesn’t necessarily mean an engine will run smoothly at peak levels of effort.

Horsepower is useful in judging how an engine will perform during a high RPM effort over prolonged periods of time (e.g. a car pulling a trailer). If you need an engine to haul efficiently, a horsepower estimate derived from a cc conversion might offer more practicality in terms of how the engine will actually run. Inspect your mower if your Briggs and Stratton backfires.

Why Are Briggs & Stratton CC and Horsepower Important to Know?

Understanding the cc and horsepower ratings of an engine can be important in relation to:

  • fuel economy
  • pulling force / torque
  • RPM
  • engine heat output
  • hauling efficiency
  • mileage
  • efficacy for short distances vs long distances

Some Considerations About Briggs & Stratton CC and Engine Power

CC ratings are determined exclusively by an engine’s design. The volume of an engine’s cylinders will not be changed regardless of tuning, RPM, fuel, exhaust pressure, turbocharging or supercharging, nor horsepower itself. However, engine displacement (cc) contributes to the amount of torque an engine produces, which in turn impacts horsepower.

Overall performance can rely on more than just the engine power ratings suggested by cc and horsepower. Component weights (e.g. lawnmower blades, car frame), center of gravity, and elements of drag in the design can impact the way equipment feels or operates – even if it contradicts the on-paper specs.

Alternate Conversions

Because horsepower and engine displacement are not directly communicable values, most formulas merely estimate a value. To increase the relative accuracy of values obtained by converting cc to horsepower, it’s best to assume a range. Most often, this range is defined as 15 to 17cc per horsepower. Returning to the conversion made earlier (125 to 140cc), the equations would take the following forms:

125 / 15 = 8.3 (8)

140 / 15 = 9.3 (9)

125 / 17 = 7.35 (7)

140 / 17 = 8.23 (8)

The resulting horsepower range would then be around 7 to 9 based on an engine displacement range of 125 to 140cc.

(Additionally, a separate conversion exists specific to small, 4 cycle engines. Rather than 15, the cc rating is divided by 32.2.)

Origin of Briggs & Stratton

Briggs & Stratton was founded through the combined efforts of Stephen Foster Briggs and Harold M. Stratton in 1908 – coincidentally, the same year Ford’s Model T was released and swept the USA. The two would go on to develop their own automobile in 1922: the Briggs & Stratton Flyer, known as the “Red Bug.” Shortly thereafter, the company would transition into small engine and component manufacturing.

Related Questions

Do high CC engines consume more or less fuel?

High cc rated engines drive a larger volume of air and fuel through each cylinder than lower cc and / or smaller engines. This generates more power, but also burns more fuel in the process. As the engine displacement increases, the overall fuel efficiency of the system will decrease.

Does higher torque mean a faster engine?

More torque means a stronger acceleration and the ability to reach certain speeds, but not necessarily a capacity for greater top speed. In this case, torque is like the force exerted by a sprinter during a 100m dash. The force of each step produces the acceleration and momentum carrying the sprinter forward. That acceleration and momentum is reflected as “rotating force” in an engine.However, without an adequate RPM (or rotating speed), the sprinter will quickly top out and have to work to maintain speed, or slow down altogether. The same is true of torque in an engine – it allows for a certain level of force exertion, but will begin to meet with diminishing returns unless the RPM can be increased as well.

What is the average power measurement for Briggs & Stratton lawn mowers?

One might wonder what the cc or horsepower rating is on an average lawnmower compared to large engine vehicles or supercars. Briggs & Stratton have a range of power ratings listed for their engine series models (450 – 1000). Their cc values rate at 125cc and 3hp on the low end, up to 223cc and 6hp for their most powerful models.Compare that to a Tesla Model S – with horsepower ratings between 670 and 1020. According to the conversion methods listed here, that translates to an engine displacement between 10050cc and 17340cc – up to and over 100x a lawn mower’s output.

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Both cubic centimeters and horsepower have their place in describing the power and performance capabilities of an engine. Conversions between them are mostly just approximations, but do serve as rough guidelines within which you can set your expectations.

Briggs & Stratton, like most in the small engine manufacturing industry, prefers to list engine displacement in cc – rather than a horsepower measurement – on their website’s product spec sheets. Associated horsepower ratings can be found elsewhere. This might be because horsepower is less relevant to small engine design considerations.

Component weight, torque, and peak power are not critical to the efficient operation of lawnmowers, pressure washers, snowblowers, and generators. Rather, these kinds of equipment rely on steady, even performance and power distribution. Take that into consideration before picking out an engine with the biggest and baddest resume.

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