QuestionDoes "horsepower" mean anything?
Hopes&Fears answers questions with the help of people who know what they're talking about. Today, we're trying to figure out if "horsepower" really means anything at all.
Car and truck commercials often boast about impressive horsepower. They lead us to believe an engine’s horsepower equates to its brawn. But what does horsepower actually mean? How can a word that references an animal measure a machine’s speed or strength? Does horsepower impact a car’s quality? Does it truly reflect an engine’s power, or is it simply a muscular marketing term? Hopes&Fears found experts to answer these very questions for us.
Classic, Race & Performance Car Expert at Dutton Garage and Founder, Dutton Grand Prix Rally
Horsepower combines the theory of work with time. Initially James Watt, the inventor of the steam engine, wanted to tell people how much power his new engine could deliver. The easiest way of describing this at the time was to compare it with a horse. If a horse could pull a certain amount of weight per second, his engine had something for the common person to relate to. This gave the public an indication of how powerful his new engines were, by working out how many horses it would take to pull the same amount of weight as one of his engines.
Horsepower is a measurement of an engine’s power. It is measured on a dynamometer that test how much power and strength (torque) the engine has before the dynamometer can stop or break it. Hence the term brake – Horsepower and torque which measures the twisting power of an engine.
To answer ‘does horsepower mean anything to car buyers and enthusiasts,’ is that this is the measurement everybody asks for in regards to the performance figures for a car that they can relate to other model cars. The more horsepower, the faster and quicker the car. For example, most formula one race cars can rev up to 18,000 RPM, and hence their horsepower is extremely high. Today the term horsepower is widely used in motor racing to describe power and performance: “the greater the horsepower, the greater the performance."
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Brand Steward at Alpha Health Products Ltd, is a lifelong gearhead and sold Volkswagens for 7 years. He relishes making technical topics understandable.
The saying is "Horsepower wins races, torque moves loads."
When looking at engine output, you will have two graphs, horsepower vs rpm, and torque vs rpm. Look and see where maximum horsepower and torque are created.
In city driving, it is not often that a driver will have the opportunity to develop maximum horsepower, as it usually happens high in the rpm range (you really have to rev the engine). So for most city driving situations, an engine that develops torque sooner will feel peppier.
Diesel engines, for instance, typically have low maximum horsepower ratings, but if they create significant torque (say, 140 lb/ft) at low rpms (say 1500), they will feel quite peppy as they will be able to move the weight of the vehicle expeditiously.
Some gas turbo engines have relatively flat torque curves that develop significant torque (200 lb/ft) at about 1700 rpm and hold that through the rpm range to 5000, before dropping off. Such an engine will feel peppy throughout the driving range.
Maximum horsepower determines top speed, the point at which the police will impound your car. Of course, it's relative to the weight of the car (think about horses pulling heavy sleds--the heavier the sled, the more horses you need).
Horsepower has nothing to do with the quality of the car. The only way it would have an impact is if the car develops significant torque at low rpm range. In that event, the engine will likely never be required to work harder than 50%, which could possibly extend its life. But that's just conjecture.
Cars with the most horsepower according to Autobytel
2015 Bentley Continental GT - 626 HP
2015 Dodge SRT Viper - 640 HP
2015 McLaren 650S - 641 HP
2015 Chevrolet Corvette - 650 HP
2015 Ferrari FF - 651 HP
2015 Tesla Model S - 691 HP
2015 Dodge Charger - 707 HP
2015 Dodge Challenger - 707 HP
2015 Lamborghini Aventador - 720 HP
2015 Ferrari F12berlinetta - 731 HP
Special Projects Director at Team O'Neil Rally School
Horsepower is a measure of torque over time, the rate of the work done to move a car (1hp=746 watts of energy). Basically, this determines how fast a vehicle can travel. Torque is simply a measure of the twisting force the engine creates as it spins, the engine's ability to turn the driveshaft and tires, making the car actually move. Horsepower is the application of this torque over time.
You need a good mix of horsepower and torque to have a fast car. High torque without horsepower will help you accelerate quickly initially and pull heavy loads, but you won't go fast (like an 18-wheeler or a tractor). High horsepower without torque won't get you off the line quickly, but you'll be able to do 50-80mph in a hurry (like a weed-whacker or a Japanese street bike).
As far as reliability goes, it's generally inversely proportional with horsepower. Drag race engines with over a thousand horsepower have to be completely rebuilt after every race. Toyota Corollas with ~100 horsepower will go over 500k miles with just oil changes.
Horsepower vs size of the engine also determines reliability. If you try to make 500hp from a small, 4-cylinder engine, you're going to blow it up pretty quickly and spend a ton of money on exotic parts and engineering. You can make the same 500hp reliably from a big 8-cylinder engine with no trouble at all in your garage at home.
This also depends on how they are used of course. Having a lot of horsepower at your disposal doesn't mean you have to use it, if you drive a high horsepower corvette around at 65mph on the highway, it'll also last forever, but no one actually does that. You could also blow up a Corolla engine in a hurry if you kept it at redline the whole time.
Generally high horsepower engines are built better in general than low horsepower engines. You need tighter tolerances and better materials to make more horsepower, everything has to be engineered more meticulously and balanced just right, they have to hold up to higher temperatures as well. The rest of the driveline also has to be better, the transmission, driveshafts, differentials, etc all have to be strong to hold up to the power while still being lightweight to keep the performance.
Moral of the story is that with a 500hp car, you do have a better engine and driveline, and if you generally only use part of that power driving around, you're fine. It's like a marathon runner walking around town, never going to have a problem... But he's more likely to have a sports injury than the average pedestrian because he does run around on the weekend.
automotive fanatic, car tech specialist, regular writer for a collaborative community designed to help ease the stress and annoyance of dealing with the DMV, http://www.dmv.com/jordan-perch
While horsepower can not be considered as a key factor for determining a car's quality, it is a factor that a car's performance greatly depends on. Acceleration time and speed are closely related to horsepower. In general the more horsepower a car has the higher its top speed is, and the faster it can accelerate to 60 mph.
Additionally, horsepower affects a vehicle's towing capacity, which is obviously especially important for trucks.
On the other hand, generally speaking, more horsepower means more fuel consumption, which means that increasing a car's horsepower usually translates into decreasing its fuel economy.
As far as durability is concerned, horsepower has nothing to do with it, because a car's longevity is affected by the quality of its components, how it is driven, and how it is maintained.
Best selling cars of 2014 according to Kelley Blue Book
Ford Fusion - 175 HP
Honda Civic - 143 HP
Honda CR-V - 185 HP
Nissan Altima - 182 HP
Toyota Corolla - 132 HP
Honda Accord - 185 HP
Toyota Camry - 178 HP
Ram Trucks - 395 HP
Chevrolet Silverado - 355 HP
Ford F-Series - 365 HP
Cars.com executive editor
The answer is, horsepower means a lot, but only in context. Horsepower is a reliable measure of an engine’s overall ability to do work. The specification itself is necessary, but it’s definitely over-marketed because, well, 300 horsepower in a two-seat sports car isn’t the same as 300 horsepower in an airport shuttle. The following affects how the power translates into acceleration.
The vehicle’s weight:
The example above is an extreme one, but it illustrates the concept. Three hundred horsepower will fling a lightweight sports car to 60 mph rapidly, while it may prove merely adequate in accelerating a van weighing literally several times a much. A specification called power-to-weight ratio does a better job of estimating how quick a vehicle might be relative to another, but automakers promote this number – you guessed it – only when the vehicle in question’s ratio is comparatively high.
The rest of the drivetrain:
The cited horsepower is for the engine alone, which doesn’t account for the power losses in the transmission, driveline and wheels – or how many gears the transmission has, which affects how well it exploits the available power.
While aerodynamics isn’t much of a factor at lower speeds, it does come into play on the way up to highway speeds, such as in a measure of zero to 60 mph. All other things being equal, a more “slippery” vehicle would be quicker.
Let’s set aside the extreme sports-car/van example and consider the more likely scenario a consumer encounters, comparing one model against a competing model: Unless the horsepower differences are dramatic, one can’t rely on the specs to reveal which car is quicker, for the reasons above. The family sedan with more horsepower than another might be heavier or for some other reason less adept at translating the available power into acceleration.
One good place for comparing horsepower is between two or more engine options for the same model – for example an optional V-6 or turbocharged four-cylinder versus the base four-cylinder. Why? Because all other factors are equal, or nearly so.
While the specifications have value, they still don’t reflect what it’s like to drive different vehicles, because the way engines deliver their power – at low engine rpm through high – varies, as do their transmissions. That’s why Cars.com’s reviewers concentrate on the experience – responsiveness, passing power, noise levels and more.
Automotive Writer at TopSpeed.com
Horsepower numbers used to be a major selling point for cars, and they still are in a way. Big numbers always look good for advertising. But there's more to it, because while cars ARE getting more and more powerful, they're also getting heavier. Heavier and more powerful cars are fun, but all that extra power makes for more strain on the drive train, chassis, suspension and tires. For that reason, a lot of engineering work today has less to do with making cars better as a whole than just compensating for the extra weight and power.
The same goes for efficiency and high-tech materials. The best of today's hybrids aren't massively more efficient than Volkswagen Rabbit Diesels were 40 years ago. But they are bigger, faster, safer and a lot more luxurious. In that sense, then, most of the horsepower, efficiency and engineering developments in the last half century haven't improved performance in any way -- they just allowed manufacturers to build bigger, faster, nicer cars.
The story with durability is the same as with efficiency: All else being equal, more weight and power never HELP. Load strain is load strain. You can compensate for that with higher-tech materials and engineering; conversely, if you used those same materials and engineering with less power and weight, the vehicle would probably last a lot longer. All things considered then, more horsepower doesn't objectively make a vehicle better in any way... But it does allow us to build vehicles that we LIKE better in almost every way.