Comparing WHP vs BHP is important when you’re learning about the power of your car. There are a lot of confusing terminologies when talking about this, and while WHP and BHP are used interchangeably by some car owners, they actually mean two different things and should not be confused with each other.
Despite meaning different things, brake and wheel power are important in understanding the power of your car. In this guide, we will cover what these terms mean and how you can calculate them as well.
|Meaning||Wheel Horsepower||Brake Horsepower|
|How to test||Multiply power output by the speed of the wheels||Dynamometer|
|Mainly affected by||Speed of the wheels||Engine size|
- 1 What Is the Main Difference Between WHP and BHP?
- 2 Features and Advantages of WHP
- 3 Features and Advantages of BHP
- 4 Conclusion
What Is the Main Difference Between WHP and BHP?
The main difference between WHP and BHP is the measuring process they use, as the WHP is measured at the wheels while the BHP is measured at the crankshaft. Both values measure the power output of the engine or electric cars.
WHP means wheel horsepower and measures based on the speed of the wheels. BHP is brake horsepower and is based on the crankshaft. The BHP considers the engine’s losses like windage and friction when calculating power output, making it a more accurate and the most common way
On the other hand, the WHP only looks at the wheels and does not take losses into account. Based on this, the BHP is more accurate in estimating the car’s performance, while WHP is used in racing applications.
Take note that you can increase the car’s speed without increasing horsepower by adding a turbocharger or supercharger to the engine. This will force more air into the cylinders, producing more air and burning more fuel.
Features and Advantages of WHP
WHP means wheel horsepower and is a measure of engine power obtained from the force exerted by the rolling wheels of the car. It is calculated by multiplying the power output of the engine in horsepower by the speed of the wheels. The concept was first introduced by James Watt, a Scottish engineer, in the 1970s.
WHP is mostly used to measure the output power of a car’s engine, especially in racing applications. The WHP does not consider some important factors that affect the engine, such as the rolling resistance or aerodynamic drag. Due to this, it is not a direct measure of the engine’s performance. Instead, it can be seen as one of the factors that affect performance.
Take note that the main difference between WHP and HP is that the WHP is the amount of power acquired when the engine is connected to the drivetrain, while the HP is the level of power that an engine makes without connecting the drivetrain, and it is measured at the flywheel.
– Testing WHP
You can test the WHP by multiplying the power output of the engine, which is in horsepower, by the speed of the car’s wheels, which is in miles per hour. To do so, figure out the weight of your car using a garage scale or a commercial scale. Next, check the speed of the wheels in miles per hour using a GPS-based speedometer or measuring the distance.
With this information, you can multiply the power output by the speed to get the WHP. For instance, if the engine produces 200 horsepower and the wheels move at a speed of 70 miles per hour, the wheel’s horsepower will be 14000.
One advantage of WHP is that it can be used in racing applications since it considers the speed of the wheels. Since it only focuses on wheels and does not consider engine losses, it is also a direct measure of the engine’s power.
The disadvantage of using WHP is the fact that it does not look at the losses of the engine. Due to this, the WHP will make the car look like it has more power than it actually does. This can reduce the accuracy of the calculation.
– Factors That Affect WHP
The main factor that affects the WHP is the speed of the wheel. The faster your car wheels move, the higher the WHP will be. Aside from that, other factors include the size of the engine, the tires you are using, the car weight, and the gearbox.
Keep in mind that the WHP does not consider the aerodynamic drag or rolling resistance of the car when you’re driving. This makes it more of an indirect measure of the car’s performance. The WHP of your car will be high when you upgrade the engine, install a nitrous oxide kit, adjust the final drive ratio, and increase the transmission ratio.
Installing a supercharger or turbocharger to your engine will also increase your WHP. The weight of your car is an important factor, as a heavier car will need more power to accelerate than a lighter car. So, the heavier the car, the lower the WPH would be. Another factor is the road condition, which can reduce or increase the WPH if it’s slick or has a good grip.
– How Much WHP Is Equal to 1 HP?
There is no specific amount for how much WHP is equal to 1 HP. To calculate the engine horsepower from the WHP, you should calculate it as HP = WHP x 1 / (1 – DL). The WHP is usually lower than the horsepower by about 45 percent.
Features and Advantages of BHP
BHP means brake horsepower, and it is a unit of measurement that is used to figure out the power output of an engine based on the crankshaft or flywheel. The BHP looks at how much power an engine can produce when it is working at its highest capacity, which is why it also considers what can reduce the power, like friction and windage.
The formula for calculating the BHP is (2 x pi x RPM x T) ÷ 500, where T is the torque output in pound-feet, RPM is the speed in revolutions per minute, pi is a constant, and 550 is a conversion factor.
Unlike the WHP, BHP is a direct measure of engine power. It can be used to compare the output of different engines, so the higher the BHP, the more powerful the engine would be. Keep in mind that the BHP does not always consider the efficiency of the engine.
– Testing BHP
You can test a BHP in different ways, but the most common method is to use a dynamometer, also known as a brake tester. The dynamometer is used to measure the engine’s power output by checking the acceleration time. Other ways include measuring on a chassis dyno or the acceleration times.
The dynamometer calculates the BHP by measuring the amount of force needed to keep the rotor speeding at a particular speed. Place the vehicle on a dyno platform and lock the wheels in place. Then, you can do the test by revving up the engine to a specific RPM and measuring the resulting force.
You can also test the BHP by measuring the engine’s power output on a chassis dyno. The dyno will measure the amount of horsepower and torque the engine produces while on the wheels. The car is placed on a roller set to do this test, and the wheels will be connected to sensors. Then, you rev up the engine to a particular RPM and measure the power output.
The final method for testing BHP is with the acceleration times. You can set a timer for how long it takes for the vehicle to meet a specific speed or how long it takes to finish a quarter-mile run. The test will determine the amount of power that the brake generates to stop the vehicle. With these in mind, you can test your BHP with the method that works for you.
The main advantage of the BHP is that it is a common way of measuring the power output of an engine. The brake horsepower is measured at the engine crankshaft and considers the losses like windage and friction. It is an accurate measure to check the power output of the engine.
The downside of using BHP to measure your engine’s power is that it includes different kinds of losses. Since it considers different things, it can be quite misleading. If an engine has plenty of friction losses, the BHP will make it look like it has less power than it does.
– Factors That Affect BHP
There are different factors that can affect the BHP of your car. The main and most obvious factor that influences the final BHP is engine size. The bigger the engine, the more BHP you would have. Also, the weight of the car will affect the BHP, as a heavier car will need more power to move it. With a heavier car, you get a lower BHP.
The kind of tires fitted to your car will also affect the BHP. If you’re using drag racing tires that have a strong grip on the road, your car will have more power. If your car has weak aerodynamics, it will work harder to drive and push through the air, reducing the BHP. You also need to consider the gearbox, as a properly tuned gearbox will increase the BHP.
If you want to increase the BHP, you need to consider all these factors. Find ways to optimize them, and this way, you can get more engine power.
– How Much BHP Is Equal to 1 HP?
1 HP is equal to just under 0.99 BHP. For instance, if a car has 200 HP, it would also have 198 BHP. It might not look different from 1 HP, but when you scale it up, you will notice the difference.
Now that you understand the differences between WHP vs BHP, you can easily calculate the speed and performance of your car.
Here’s a handy rundown of what we covered in our guide:
- WHP means wheel horsepower, and it measures the power output of a car’s engine based on the speed of the wheels.
- The WHP is tested by multiplying the power output of the engine in horsepower with the speed of the wheels in miles per hour.
- The BHP means brake horsepower and is used to measure the power output of your engine based on the crankshaft.
- It is tested with a dynamometer, checking the acceleration time and the output on a chassis dyno.
- The BHP is an accurate way to measure the car’s engine power because it considers engine losses, while the WHP is better for racing applications.
If you’re trying to decide what engine to use for your car or how much power you need, you should consider calculating the WHP and BHP first.
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