Difference Between HP and BHP

Power is defined as the capacity of doing work. Its value is found by dividing the energy of the system by the time.

HP vs BHP

The difference between hp and bhp is that the hp is a unit of measurement of the power of the entire system and does not include frictional losses, whereas the bhp is the amount of the power output by the engine and includes frictional losses.

The horsepower or hp is a unit of measurement of the output power of a mechanical or electrical system. It has various types such as the metric hp and the mechanical hp.

The brake horsepower or bhp is the amount of engine power of a mechanical or electrical system. It also takes into account the various losses due to friction the engine.

---

 

Comparison Table

Parameter Of Comparison	hp	bhp
Definition	hp stands for horsepower. It is the total output power of a system.	bhp stands for brake horsepower. It is the output power of the engine of a system.
Measured For	It is measured for the whole system and gives the efficiency of the system.	It is only measured for the engine of the system and gives the efficiency of the engine under ideal conditions.
Frictional Losses	It doesn’t take the frictional and other power losses into account.	It includes the frictional and other power losses of the system.
Measured Using	It is measured using a simple dynamometer.	It is measured using a brake type dynamometer.
Technique for Measurement	The dynamometer is connected to the engine, and a torque converter is used.	A brake is applied to the flywheel, and the intensity of this brake determines the bhp.

---

 

What is HP?

The horsepower is the unit of measurement of the output power of a system. It is represented by hp and is a supplementary unit.

The following formula is used for the measurement of horsepower :

P[hp] = ( τ[ft. lbf] × N[rpm] ) /5252

Here, τ is the torque, and N is the speed of revolution of the engine.

To measure the horsepower of an engine, a dynamometer and a torque-converter is connected to the engine.

1. The mechanical horsepower is represented by hp[l]. It is equal to 76.04 kgf. m/s or 550 ft-lbf/s.
2. The metric horsepower is represented by hp[M]. It is equal to 75 kgf. m/s or 542.47604 ft-lbf/s.
3. The Electrical horsepower is represented by hp[E]. It is equal to 746W.

 

What is BHP?

The brake horsepower is the amount of power output by the engine. It is represented by bhp.

The measurement of brake horsepower is carried out under controlled conditions in a laboratory. The measurement is done on either the crankshaft or the wheels of the system.

The brake horsepower is always higher than the horsepower.1bph is equal to 1.013869 hp.

---

Main Differences Between HP and BHP

The horsepower is a useful supplementary unit for the measurement of large amounts of power. It is different from brake horsepower.

The main differences between the two are :

1. The horsepower hp is the output power of a mechanical or electrical system, whereas the brake horsepower bhp is the output power of the engine.
2. The hp is measured for determining the efficiency of the entire system, whereas the bhp is measured for determining the efficiency of the engine only.
3. The hp doesn’t include the power losses in the form of friction. On the other hand, the bhp includes the frictional losses too.
4. The hp is measured using a simple dynamometer, whereas the bhp is measured using a brake type dynamometer.
5. The hp is usually less as the losses are subtracted from it, whereas the bhp is higher as it includes the losses also.

---

References

1. https://www.sae.org/publications/technical-papers/content/770465/
2. https://journals.sagepub.com/doi/pdf/10.1243/PIME_PROC_1924_106_024_02