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Twincam16
Original Poster
27,438 posts
128 months
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When (and why) did people start using this abbreviation?
It's short for 'pferdenstark', which is German for 'horsepower'.
So what's wrong with 'hp' then?
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CampDavid
7,843 posts
68 months
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Twincam16 said: When (and why) did people start using this abbreviation?
It's short for 'pferdenstark', which is German for 'horsepower'.
So what's wrong with 'hp' then? It's actually a different measurement, the German's have weedy horses compared to ours. Multiply your manly HP figure by 1.01387 to get the PS value for pussy German horses
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NiceCupOfTea
22,058 posts
121 months
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It's "metric" horsepower isn't it? I seem to remember hp/bhp is a very arcane definition.
I would have thought you would have known the answer quoting them every day in your job?
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Mr2Mike
9,617 posts
125 months
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It's a "metric" horsepower which is defined in "round" SI units which gives a power close to, but not quite the same as, James Watts original imperial definition. This was published as a DIN standard in 1976, so it's been around a fair while.
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Twincam16
Original Poster
27,438 posts
128 months
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NiceCupOfTea said: It's "metric" horsepower isn't it? I seem to remember hp/bhp is a very arcane definition.
I would have thought you would have known the answer quoting them every day in your job? The cars I test tend to have power measured in bhp when new. This whole 'ps' thing seems to be a fairly new fad. Also, Autocar puts horsepower figures up in the back of its mag alongside the manufacturers' 'ps' codes and the numbers seem to be the same. Just writing it in another language doesn't change the definition of what it is (although even that's confusing - an equestrian mate of mine once told me that a horse actually has 4hp as it's something to do with the power put through each leg of the horse - he could have been talking b  ks though).
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Twincam16
Original Poster
27,438 posts
128 months
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Mr2Mike said: It's a "metric" horsepower which is defined in "round" SI units which gives a power close to, but not quite the same as, James Watts original imperial definition. This was published as a DIN standard in 1976, so it's been around a fair while. Yeah, but it was 'DIN hp' and was quoted as such in road tests throughout that transition period, then accepted as just 'hp' or 'bhp'. I do wonder whether this whole 'ps' thing has something to do with manufacturers not wanting to use the word (or letters to the effect of) 'power' in their advertising literature in case it upsets the comically oversensitive types in Brake who'll write to the ASA the minute anyone suggests a car might actually be fun to drive.
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Captain Muppet
6,265 posts
135 months
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Twincam16 said: Also, Autocar puts horsepower figures up in the back of its mag alongside the manufacturers' 'ps' codes and the numbers seem to be the same. Maybe they don't understand what the numbers mean. They are writers, not engineers.
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NiceCupOfTea
22,058 posts
121 months
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Twincam16 said: The cars I test tend to have power measured in bhp when new. This whole 'ps' thing seems to be a fairly new fad. Fair enough  I think it's been in common use for 10 years or so - my wife's 2002 Puma is 125 PS or something, but I think my old 2000 Rover 25 was 110 bhp.
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bigandclever
6,406 posts
108 months
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wiki said: PS
This unit (German: Pferdestärke = horse strength) is no longer a statutory unit, but is still commonly used in Europe, South America, Japan and India especially by the automotive and motorcycle industry. It was adopted throughout continental Europe with designations equivalent to the English horsepower, but mathematically different from the British unit.
DIN 66036 defines one horsepower as the power to raise a mass of 75 kilograms against the earth's gravitational force over a distance of one metre in one second; this is equivalent to 735.49875 W. Similar definitions were already common to the time of James Watt.
The PS was adopted by the Deutsches Institut für Normung (DIN) and then by the automotive industry throughout most of Europe, under varying names. In 1992, the PS was rendered obsolete by EEC directives, when it was replaced by the kilowatt as the official power measuring unit. It is still in use for commercial and advertising purposes, in addition to the kW rating, as many customers are still not familiar with the use of kilowatts for engines. So there you go, according to the EEC it's been obselete for 20 years. No wonder people still use it 
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Captain Muppet
6,265 posts
135 months
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Twincam16 said: I do wonder whether this whole 'ps' thing has something to do with manufacturers not wanting to use the word (or letters to the effect of) 'power' in their advertising literature in case it upsets the comically oversensitive types in Brake who'll write to the ASA the minute anyone suggests a car might actually be fun to drive. Nah, it's nothing to do with avoiding the word "power" and everything to do with if you use "ps" you get a bigger number for free. 200ps sounds much better than 197bhp. ETA also 200ps is only 147kW. Smaller numbers are bad.
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SSBB
507 posts
26 months
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Seems to me that we should us imperial horsepower or metric kW. We don't buy fuel in imperial litres or weigh ourselves in metric pounds. Car makers probably like metric hp because it inflates the value slightly.
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Agrispeed
750 posts
29 months
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Horsepower is ridiculously inaccurate, I seem to remember it was when mechanized farm equipment first came into use, and it was the measurement of what one normal horse could plough in a certain time. however, it's even inaccurate to animals as they have a range of power, and can produce much more than normal when stressed (the same for people) it was a existing measurement that was sort of bodged to fit cars when they first came out, as they were the current measurement for steam engines... This might be complete b ks though 
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Mr E
14,184 posts
129 months
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I always liked the description of "smaller, metric horses"
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Twincam16
Original Poster
27,438 posts
128 months
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Mr E said: I always liked the description of "smaller, metric horses" I quite like the idea of something like a Bentley as having 'sufficient shire horses', a Ferrari as having a comically overstated number of thoroughbred Arabian race-stud stallions, a Mini as having Shetland ponies and a Citroen 2CV to be measured in donkeys.
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paranoid airbag
1,335 posts
29 months
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Agrispeed said: Horsepower is ridiculously inaccurate, I seem to remember it was when mechanized farm equipment first came into use, and it was the measurement of what one normal horse could plough in a certain time. however, it's even inaccurate to animals as they have a range of power, and can produce much more than normal when stressed (the same for people) it was a existing measurement that was sort of bodged to fit cars when they first came out, as they were the current measurement for steam engines... This might be complete b ks though It does have an accurate definition, that is based on what James Watt estimated one horse to be capable of achieving (sustainably - even humans can top 1hp for short bursts). 1hp is equal to the capability to move a 550lb force at a rate of 1 foot per second (or 225lbs at 2 feet per second, or 1lb at 550ft per second, etc.).
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Captain Muppet
6,265 posts
135 months
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The big question is whether ps is better than Nm.
[/obvioustroll]
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Mr E
14,184 posts
129 months
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Captain Muppet said: The big question is whether ps is better than Nm.
[/obvioustroll] The engineer in me is trying to resist....
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crofty1984
9,925 posts
74 months
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Captain Muppet said: The big question is whether ps is better than Nm.
[/obvioustroll] You dick.
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SSBB
507 posts
26 months
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Captain Muppet said: The big question is whether ps is better than Nm.
[/obvioustroll] lb.ft wins. Torque wins races...
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Mr2Mike
9,617 posts
125 months
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Twincam16 said: Yeah, but it was 'DIN hp' and was quoted as such in road tests throughout that transition period, then accepted as just 'hp' or 'bhp'. That's a different thing again. Power ratings were referred to as DIN to differentiate them from the old American SAE standard. The later gave inflated power ratings by testing the engine with none of the normal ancillaries attached to it (alternator, power steering etc.).
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