Hello Everyone and Welcome to This Week's Video: Understanding Engine Horsepower Versus Wheel Horsepower

Today, we're going to be discussing engine horsepower versus wheel horsepower. I want to start by explaining what each of these terms means. Put very simply, engine horsepower is the horsepower your engine creates measured at the flywheel, while wheel horsepower is the horsepower that your car makes measured at the driven wheels.

To understand this better, let's take a look at an example. We have our engine, a two-cylinder engine, and it's rotating this crankshaft, which is rotating the flywheel. Measuring engine horsepower involves using an engine dynamometer to break against this flywheel and measure the torque that it supplies at a certain RPM. Once you have this torque and RPM, you multiply them together and divide by 5252, which gives you your horsepower.

However, there are several things that manufacturers exclude when measuring engine horsepower. If a car has power steering, they won't account for the power required to steer the car. Similarly, if the air conditioner is on, it drains power from the engine, so this isn't included in the measured horsepower. Other things like the alternator, which powers all the electrical and recharges the battery, may also not be accounted for.

This leaves us with only a portion of the total energy output of the engine, rather than its actual gross output. This is because manufacturers want to give you an accurate representation of how much power your car can actually produce on the road, taking into account all the factors that affect it. So, if they were to put a very restrictive exhaust system on the car, the measured horsepower would be different from what you'd experience in real-world driving.

On the other hand, we have wheel horsepower. This is the same measurement as engine horsepower, but it's taken at the driven wheels rather than the flywheel. To measure this, you use a dynamometer that puts the wheels on and measures the torque supplied to them at a certain RPM. Once again, you multiply this torque by the RPM and divide by 5252 to get your wheel horsepower.

Within our drive line, there are several components that reduce engine power. Let's start with the clutch. The clutch is responsible for transferring torque from the engine to the transmission, and it has a better efficiency at doing so than some other types of clutches or gearboxes. However, this means that some energy is lost in the process.

We also have torque converters, which are commonly used in automatic transmissions. They're spinning in a fluid, which creates frictional losses, leading to even more energy being lost from our engine power. This is one reason why automatic transmissions may be rated with lower horsepower than their manual transmission counterparts.

Moving on, we have the gears themselves. To spin these gears, they need friction, and this friction creates heat that's converted into energy loss. So, not only are there losses in the clutch and torque converter, but there are also losses in the gears themselves.

Finally, we have u-joints and differentials between the transmission and drive shafts. These components create even more friction, leading to further energy loss. This means that a significant portion of our engine power is being wasted as heat due to these various components.

As a general rule of thumb, two-wheel drive vehicles typically lose around 10-15% of their engine power due to frictional losses throughout the drivetrain. This means that if your car has a 200 horsepower engine, you can expect it to only produce around 180-190 horsepower after accounting for these losses.

If you have a four-wheel drive or all-wheel drive vehicle and are driving with all four wheels on the ground, you'll lose even more power due to the increased friction. This means that your wheel horsepower will be reduced by around 20-25% compared to your quoted engine horsepower.

"WEBVTTKind: captionsLanguage: enhello everyone and welcome to this week's video today I'm going to be explaining engine horsepower versus wheel horsepower now I want to start getting into ways to increase horsepower and ways to make your car accelerate more quickly and so before I do that it's important to understand engine horsepower and wheel horsepower now put very simply engine horsepower is the horsepower your engine creates measured at the flywheel wheel horsepower is the horsepower that your car makes measured at the The Driven wheels so here we've got an example we've got our engine our two-cylinder engine and it's rotating this crankshaft which is rotating the flywheel now measuring engine horsepower that's where it ends so you'll use a engine dynamometer and what you'll do is you'll break that against this flywheel and you'll measure the torque that this flywheel supplies at a certain RPM now you take that torque and RPM multiply them together and divide by 5252 and that'll give you your horsepower so if you don't understand this equation um I've got a video explaining horsepower and torque you should check out to get that information now one of the things that is excluded well there's several things that are excluded when you measure engine horsepower when manufacturers say okay we're going to give you uh this new car and it has 200 horsepower and they're giving you the engine horsepower now the reason they're giving you the engine horsepower is because it's always higher than the wheel horsepower so what are some of the things that they might exclude from the engine horsepower well if it has power steering they're not going to account for the power required uh in order to steer the car they also may not include the power if you have your air conditioner on you have to run a compressor and that drains power from your engine other things that may drain uh Power from your engine that might not be included in what the manufacturers claiming is the horsepower include the alternator um which Powers all the electrical and recharge the battery the water pump and if you have a restrictive exhaust so they may measure engine power without a very restrictive exhaust and then put a restrictive exhaust on the car and then the engine horsepower is going to be a bit different so on the other side what we've got going on is wheel horsepower so the same way you measure it using a dynamometer that you put the wheels on and you measure the torque supplied at a certain RPM use your equation and you can figure out the horsepower now within this whole Drive Line we've got all kinds of things that are going to reduce our engine power so starting with the clutch um this could be a torque converter and clutches are typically going to have a better efficiency at transferring all of the torque uh whereas a torque inverter is spinning in a fluid and so there'll be frictional losses that's why with some Vehicles you may see that the automatic is rated at uh a higher horsepower or a lower horsepower sorry than the manual and they're taking into account the torque converter um so next up we've got our transmission So within that you've got Gears that are all spinning and for those gears to spin obviously you need friction and that friction creates heat and so that heat is lost energy so once again more energy lost from our quoted 200 horsepower or whatever the manufacturer is claiming You've Got U joints between your uh transmission and your drive shaft and your drive shaft and your differential um so you've got friction uh within your differential you've got friction going out to the wheels and so all of this friction means that you're going to lose uh some of that engine horsepower so as a general rule of thumb um a two wheel drive vehicle is typically going to lose somewhere uh at about 10 to 15% of its engine power um probably around the 15% area uh because of all the frictional losses throughout the drivetrain now if you have a four-wheel drive vehicle or an all-wheel drive vehicle and you're driving all four wheels then you're going to obviously have a lot more friction and so you can expect to lose a bit more of your engine horsepower so your wheel horsepower is going to be maybe around 20% to 25% less than what your quoted engine horsepower is so I hope now you have a better understanding of engine horsepower and wheel horsepower and so now we can start kind of getting more into detail of how can we increase engine horsepower how can we increase wheel horsepower how can we make a car go fasterhello everyone and welcome to this week's video today I'm going to be explaining engine horsepower versus wheel horsepower now I want to start getting into ways to increase horsepower and ways to make your car accelerate more quickly and so before I do that it's important to understand engine horsepower and wheel horsepower now put very simply engine horsepower is the horsepower your engine creates measured at the flywheel wheel horsepower is the horsepower that your car makes measured at the The Driven wheels so here we've got an example we've got our engine our two-cylinder engine and it's rotating this crankshaft which is rotating the flywheel now measuring engine horsepower that's where it ends so you'll use a engine dynamometer and what you'll do is you'll break that against this flywheel and you'll measure the torque that this flywheel supplies at a certain RPM now you take that torque and RPM multiply them together and divide by 5252 and that'll give you your horsepower so if you don't understand this equation um I've got a video explaining horsepower and torque you should check out to get that information now one of the things that is excluded well there's several things that are excluded when you measure engine horsepower when manufacturers say okay we're going to give you uh this new car and it has 200 horsepower and they're giving you the engine horsepower now the reason they're giving you the engine horsepower is because it's always higher than the wheel horsepower so what are some of the things that they might exclude from the engine horsepower well if it has power steering they're not going to account for the power required uh in order to steer the car they also may not include the power if you have your air conditioner on you have to run a compressor and that drains power from your engine other things that may drain uh Power from your engine that might not be included in what the manufacturers claiming is the horsepower include the alternator um which Powers all the electrical and recharge the battery the water pump and if you have a restrictive exhaust so they may measure engine power without a very restrictive exhaust and then put a restrictive exhaust on the car and then the engine horsepower is going to be a bit different so on the other side what we've got going on is wheel horsepower so the same way you measure it using a dynamometer that you put the wheels on and you measure the torque supplied at a certain RPM use your equation and you can figure out the horsepower now within this whole Drive Line we've got all kinds of things that are going to reduce our engine power so starting with the clutch um this could be a torque converter and clutches are typically going to have a better efficiency at transferring all of the torque uh whereas a torque inverter is spinning in a fluid and so there'll be frictional losses that's why with some Vehicles you may see that the automatic is rated at uh a higher horsepower or a lower horsepower sorry than the manual and they're taking into account the torque converter um so next up we've got our transmission So within that you've got Gears that are all spinning and for those gears to spin obviously you need friction and that friction creates heat and so that heat is lost energy so once again more energy lost from our quoted 200 horsepower or whatever the manufacturer is claiming You've Got U joints between your uh transmission and your drive shaft and your drive shaft and your differential um so you've got friction uh within your differential you've got friction going out to the wheels and so all of this friction means that you're going to lose uh some of that engine horsepower so as a general rule of thumb um a two wheel drive vehicle is typically going to lose somewhere uh at about 10 to 15% of its engine power um probably around the 15% area uh because of all the frictional losses throughout the drivetrain now if you have a four-wheel drive vehicle or an all-wheel drive vehicle and you're driving all four wheels then you're going to obviously have a lot more friction and so you can expect to lose a bit more of your engine horsepower so your wheel horsepower is going to be maybe around 20% to 25% less than what your quoted engine horsepower is so I hope now you have a better understanding of engine horsepower and wheel horsepower and so now we can start kind of getting more into detail of how can we increase engine horsepower how can we increase wheel horsepower how can we make a car go faster\n"