When getting a car, one of the most important attributes to know about it is its engine power. Here you look at the engine’s output to see how well it will fare when driving. The unit of measurement is horsepower.
The term came when an engineer tried to compare the production of steam engines to that of horses. Horsepower exists in many forms, and in this article, we will tackle WHP vs. HP.
They are two key concepts in understanding engine powers, and you should also know how to convert WHP to HP as part of their relationship.
Before taking an in-depth look at the two variables, it would help to understand what they mean. WHP stands for wheel horsepower, while HP is horsepower. Let us not delve deeper to know more about their relationship to the vehicle’s engine.
What is WHP?
Looking at the meaning of the initials (WHP) can lead you to the WHP meaning. You can get a clue as to what it signifies from the wheel horsepower, as stated earlier. Wheel horsepower is a measure of an engine’s power.
It implies you take into account the power output, like the way the wheels of an automobile move. An essential metric that reveals the amount of power transmitted from the engine to the wheels is the wheel horsepower.
Typical horsepower, often called brake horsepower, is greater than the WHP. The variation arises from the way power is transferred from the axles and other associated components to the wheel. Friction is another factor that will exert significant force.
This is often the situation with AWD cars. The actual horsepower as measured at the wheels is often lower than the stated horsepower in these vehicles.
This number indicates the amount of power lost by your vehicle’s drivetrain. A indicator of damaged or worn-out components could be an increase in its fluctuation. Keep in mind that different drivetrains will result in different crank-to-wheel HP losses.
The loss for front-wheel drive automobiles is around 10% and for rear-wheel drive cars it is about 15%. With a loss of 20%, all-wheel-drive power trains are the worst. This is likely caused by the vehicle’s gearbox attempting to disperse power to each wheel.
How Is WHP Tested?
The first step is to determine the weight of the vehicle you will be testing. This can be done by weighing the car on a commercial scale or by using a simple garage scale.
Next, you need to determine the speed of the wheels in miles per hour. This can be done by measuring the distance traveled in a certain amount of time, or by using a GPS-based speedometer.
Once you have these two pieces of information, you can calculate WPH by multiplying the engine’s power output in horsepower by the speed of the wheels in miles per hour.
For example, if an engine produces 100 horsepower and the wheels are moving at a speed of 50 miles per hour, the WPH would be 5000.
What Affects WPH?
WPH is also affected by many of the same factors as BHP. In addition, WPH is also affected by the speed of the wheels. The faster the wheels are moving, the higher the WPH will be.
However, WPH does not take into account aerodynamic drag or rolling resistance. As such, it should not be considered a direct measure of a car’s performance. A car’s WPH can be increased by:
- Upgrading the engine
- Increasing the transmission ratio
- Installing a nitrous oxide kit
- Adding a turbocharger or supercharger
- Adjusting the final drive ratio
WPH can also be affected by the weight of the car. Heavier cars will have a lower WPH than lighter cars. This is because they require more power to accelerate at the same rate.
Finally, WPH is also affected by road conditions. Slick roads will reduce WPH, while grippier surfaces will increase it.
What is HP?
One way to measure the output power of a mechanical or electrical system is in horsepower, abbreviated as HP. This measurement does not take friction into account. The debate between BHP and HP is prompted by the definition.
The power at the engine’s flywheel is measured in braking horsepower, or BHP. The BHP takes into consideration the engine’s net energy, which includes the loss caused by friction. It is confusing and incorrect for many people to use the two words interchangeably.
Multiplying the torque by the speed yields the horsepower. Finding the value is as simple as hooking up a dynamometer and torque converter to the engine.
Under regulated settings, the braking horsepower is measured on the flywheel. In order to maintain a constant engine speed, you must brake. It is common practice to use the BHP rather than the horsepower.
A brake horsepower is 1.014 times the same as a horsepower. It could be an indication of an engine problem if you find that your horsepower is lower than anticipated. Engine knocking and broken parts are among the complaints.
How does BHP compare to crank HP? Either the flywheel or the crankshaft is used to measure horsepower, and the two are identical. Keep in mind that when comparing the HP and BHP values, the BHP value will be greater because it accounts for frictional losses.
How to Calculate WHP to HP?
When looking at the engine power, you have the one the manufacturer indicates to you. This is the horsepower, and, as earlier mentioned, it does not account for factors like drivetrain loss and friction.
On the other hand, the wheel horsepower will account for these variables and show you the energy on your wheels. It is a value to consider to know how much power the car uses in motion.
The drivetrain loss comes due to the vast effort of the engine to transmit energy to the wheels. For instance, from the engine, differentials, the prop shaft, and drive shafts, then to the wheels. It is too much effort, and you will lose significant energy values.
Back to the calculation, there is the point of the drivetrain you are using and how it determines your HP to WHP value. An example is the 10% loss for front-wheel vehicles. Averagely, cars will lose 15% of their power from the engine to the wheels.
To show you how to get an HP value, we will use 200 WHP to BHP. Accounting for the loss, we will multiply it by 115 and then divide it by 100 for the percentage. The final value is 230 BHP.
However, 1 Horsepower is equal to 1.014 BHP, so to get the right HP, we further divide by the 1.014 to give us 226.82 HP. This value is the power coming from the engine.
Comparison Between: BHP vs WHP vs HP
Let’s look at the difference between horsepower and BHP and WHP:
| Parameter | HP | BHP | WHP |
| Meaning | Power generated at the flywheel | Power delivery before reaching the driveline | Power delivery at the wheels and pavement |
| Accuracy | Inaccurate | More accurate | Most accurate |
| Formula to Calculate | 1hp = 550ftlb/s | BHP=(torque x rpm)/5252 | WHP=EHP/DTLF |
| Device Used for Measurement | Engine dynamometer | Brake-style dynamometer | Chassis dynamometer |
| Determining Factors | Air pressure, air temperature, fuel quality, engine wear, engine design, etc. | Engine size, weight, tyres, gearbox, aerodynamics, etc. | Speed of wheels without taking rolling resistance and aerodynamic drag into account. |
FAQs.
Q: How Do You Convert HP To WHP?
To convert HP to WHP, you will need a calculator and an understanding of your vehicle’s drivetrain. You can first convert the HP to BHP by multiplying the value by 1.014.
Finally, you account for a 15% average reduction in flywheel power before it goes to the wheels. In this case, it is 0.85 multiplied by your BHP to get to your wheel horsepower.
Q: What Does The HP At The Wheels Mean?
The HP at the wheels refers to the engine power that reaches the vehicle’s wheels. It is usually less than the HP due to drivetrain loss, mostly caused by friction.
Q: Does HP Stand For Horsepower?
Yes, in the auto-mechanic field, HP stands for horsepower, which is the engine’s output. There are different kinds of horsepower, such as the wheel, the braking, and the crankshaft horsepower. You will find that the most powerful engines have higher horsepower.
Q: How Much HP Do You Lose From The Crank To The Wheels?
When the transmission system relays power from the crank or flywheel to the wheels, some of it gets lost.
The loss depends on the drivetrain; for instance, you will have a 10% loss for front-wheel-drive cars, 15% loss for rear-drive, and up to 20% for all-wheel-drive vehicles.
Q: How Much Horsepower Do You Lose With An Automatic Transmission?
An automatic transmission will drain up to 100 horsepower in the engine output, mostly due to torque converter slippage. The value is relatively low with manual transmission vehicles. Running the hydraulic pressure pump also contributes to energy loss.
Q: How Much HP Is BHP?
In the HP vs. BHP discussion, you notice that the BHP is slightly higher than the HP as it brings to book loss via friction. In this case, the proper estimation of HP to BHP is 1 HP, equal to 1.014 BHP.
Q: Does A Transmission Increase Horsepower?
No, the transmission does not increase horsepower; instead, it may reduce it. It is more of a stabilizer as it relays energy from the engine to the wheels. However, modifications to the transmission unit can help increase speed or improve acceleration power.
Q: Is Manual More Powerful Than Automatic?
Yes, in a way, the manual transmission is more potent than its automatic counterpart. One of the reasons behind its power is that it is less prone to parasitic power losses.
Such losses can be in the automatic system’s torque converter and clutches. Manual transmission beats this and sends all the power to your wheels.
Final Word
When getting a car, you should pay attention to its energy output, which is horsepower. If you want a more powerful vehicle, go for one with higher horsepower.
From this article, you understand that the engine’s power will reduce significantly by the time it reaches the wheels. With a WHP to HP converter, you can know the power that the vehicle loses depending on its drivetrain.
In case of a significant power drop, you have to check for engine problems, as there may be an underlying issue.