The BSA A7-A10 Forum
Technical (Descriptive Topic Titles - Stay on Topic) => A7 & A10 Engine => Topic started by: tombeau on 22.09. 2008 11:14
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Hello,
Anyone got these figures for a Road Rocket?
I need 'em for insurance quotes.
Cheers,
iain
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No idea on dry weights and I assume Kw:s to be maybe kilowatts ? Although nothing to do with electricity as I had originally thought when I first got my bike... (Here was me thinking I had a terriffic dynamo!!) It's to do with power output ratio along with braking horse power. (I think i'll stop now before I look too stupid!) *dunno*
Back then when I passed my test I found the A10 to be around 33 braking horse power although sales brouchers told us it was 35, I never saw that evidence (wonder if manosound Richard can come up with that?) So I was able to ride on a class A licence.
I'll stop now... :P waffle waffle
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1 bhp is 748Watts I think. So, for example, the 40-odd bhp for a Road Rocket (if that's about right) is approximately 75% of that in kW, which would be . . . 30kW. Nudge downwards for cheaper premiums, no doubt!
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On 12.4.08, 'The A10 1954 Instruction Manual' was posted on this site, listing the various engine outputs. The RR was listed at 40 hp @ 6000 rpm and 8:1 compression ratio. Forty hp translates to 29.92 kW, using groilly's (correct) conversion factor.
Use the dry weight as given in Owen Wright's 'Super Profile' of 418 lb for the SR.
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Well, thanks for the vote of confidence L.J. I would have cited the same conversion factor. The question is, why rate the engines in kW.My only thought, without doing what would be simple research, is that it relates the horsepower to a more scientific unit that is directly related to heat and, posssibly in turn, emissions.
Richard
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I suppose Kw is just the accepted metric unit for power. Imperial units are no longer politically correct *sarcastic*
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For me, engines will always be in "hp". I am just not ready to be enthused or impressed by a P-51 Allison engine at 750kW, but give me "1000 hp" and I can feel the rumble without an airplane present. For "750 kW" I want to see a really bright light bulb. Don't get me wrong, I inderstand the use of the units, being degreed in electrical engineering, but some things are in the blood. Be honest, did you learn about engines and "feel" their power based on their hp rating or their kW?
Richard
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I agree with Richard if an hp is a bhp! But are you, Richard, familiar with the arcane UK horse-power formula of old, which gave the taxable rating of engines in the old days, and held back engine development for cooking cars appreciably? (Because a long stroke had the effect of reducing the horse-power rating - with good reason!). Austin 7, Morris 8, Standard 10, Rover 14, Rolls 20, etc etc etc. Too arcane to quote the calculation here unless you want it - and I'd have to go and check in a book.
And what's a PS anyone? I see my Yamaha has lots of them apparently, but I had never given it any thought until this thread started!
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Dry weight is 423Lbs. According to BSA.
(https://www.a7a10.net/forum/proxy.php?request=http%3A%2F%2Fkevindean.zenfolio.com%2Fimg%2Fv4%2Fp374690171.jpg&hash=358ccad9022b1b4313f42e1398b3965457587e5a)
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P S = Pony Size.
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Pony Size? Seriously?
Yes, BHP, but when talkin', maybe just "Horse."
Richard
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I have no idea what PS means but when the Japanese bikes first became available in large capacities and quoted PS horsepower we laughed at them and laughingly called it Pony Size.
Who's laughing now?
Trev.
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But a pony only slightly smaller than a standard horse. This from Wikipedia "Horsepower":-
This (PS) unit (German: Pferdestärke = horse strength) is no longer a statutory unit, but is still commonly used in Europe, South America and Japan, 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. It is defined by the Physikalisch-Technische Bundesanstalt (PTB)[5] in Braunschweig as exactly:
1 PS = 75 kilopond·metre/second ~= 735.5 newton·m/s ~= 735.5 W ~= 0.7355 kW ~= 0.98632 hp (SAE)
Makes much more difference whether power measured at crank or rear wheel than assuming metric PS is same as BHP, and that nugget is often not made crystal. Anyone know what a 'kilopond' is?
cheers, Mike
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From Wikipedia
(Redirected from Kilopond)
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The unit kilogram-force (kgf, often, incorrectly, just kg) or kilopond (kp) is defined as the force exerted by Earth's gravity on one kilogram of mass. Although the gravitational pull of the Earth varies as a function of position on earth, it is here defined as exactly 9.80665 m/s². So one kilogram-force is by definition equal to 9.80665 newtons.[1][2] Similarly a gram-force is 9.80665 milli-newtons (or 0.00980665 newtons), and a milligram-force is.... 9.80665 micro-newtons (or 0.00000980665 newtons).
All the best - Bill
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All emotional attachments to units of measure aside, period road tests rate the 59 Road Rocket with 46 hp (34 kW) and the '61 model with 43 hp (32 kW).
BTW, here's a handy unit conversion site I use all the time: http://www.convert-me.com/en/
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Motorcycles are all about emotion (our's and our wives').
So, for me, give me horsepower over Watts. Refer to photos for one horsepower versus one Watt.
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^^ *smile*
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If I remember correctly, that old ancient Horse Power description of the old cars was 100cc = 1 Horse, so a Standard 10 was about 1000cc.
30 years ago I knew an old wartime mechanic and he used to use that way to describe any engine. An Austin 1100 to him was an "Austin 11 Horse". - maybe it was just slang.
;)
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Here in Oz the taxable horse power on bikes, if I remember correctly, was - 250cc = 2 1/2, 350cc = 2 3/4, 500cc = 3 1/4,
650cc = 4 1/2.
Trev.
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The UK's old RAC horsepower formula was this (I went and looked!): Diameter of cylinder (in inches) squared, times number of cylinders, all divided by 2.5. Hence, long strokes were 'favoured' in taxation terms versus short stroke engines, by the hp rating being lower for the same capacity. The logic of the formula was good, however. The consequence was that legislators and administrators inadvertently promoted less efficient engines. But then we didn't have a global fuel crisis and all the rest of it in those days, nor did we have roads where we could cruise along at any speed you like.
If anyone wants to pursue, just google 'RAC Horsepower Formula', and read away! In those days, it led to engines of certain capacity loosely being described as Trevinoz says. Or 15/50, 16/60 etc, where the first number is the RAC hp, the second the bhp. Wolseley cars were some of the last to maintain this dual description, until the end of the '50s. Not all countries did it the same way, but for many years tax discs/registration fees were priced according to (arbitrary) power output in many places, and even today in France at least, the 'Fiscal Horsepower' dictates the registration fee payable when getting a log book. An A 10 is rated at 7, a B31 at 4 (if I understand the papers correctly). Which ties in not too badly with 100cc to the horsepower. Amazing how these legacies from the earliest days linger on.