Alez
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| posted on 16/4/04 at 07:36 AM |
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BPH per ton, concept?
Morning All!
I was thinking about the figure of BHP per ton and the way it is calculated..
1. Is it "per metric tonne" [1000 kg] or "per ton" [907 kg or 2000 lb is a "short ton" I think, or 1016 kg or 2240
lb is a "long ton"]? You British people always trying to confuse the world with your unit system!  
2. The BHP figure used, is it definitely BHP measured at the wheels?
BTW, I've found that here in Spain, it's becoming increasingly common to use the reverse of these figures: 8 kg / BHP is fine, 4 kg / BHP
is very nice and so on.
Cheers,
Alex
[Edited on 16/4/04 by Alez]
[Edited on 16/4/04 by Alez]
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JoelP
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| posted on 16/4/04 at 08:03 AM |
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its usually 1000kgs in england, i think most people dont really know about old tonnes, certainly i dont and most younger people will be the same!
also, people often confuse power at the wheels and power at the flywheel, and often just quote the manufacturers figures, whatever those may be.
i prefer bhp/ton, rather than kg/bhp, mainly cos its easier to compare to other known figures then.
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Jasper
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| posted on 16/4/04 at 11:20 AM |
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Alez - is this for a 'mines bigger than yours' argument 
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ned
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| posted on 16/4/04 at 11:26 AM |
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I always thought that most people quote bhp at the flywheel. I appreciate this is not necessarily the most accurate when the car is on the road due to
inefficencies in the transmission, but must be the easiest to test/record, especially for a manufacturer on a dynomometer. Likewise on a rolling road
I guess at the wheels is easiest to measure accurately as the normally guess a percentage loss on the transmission and then make up an at the flywheel
figure.
or am i just talking bollox?
Ned.
beware, I've got yellow skin
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JoelP
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| posted on 16/4/04 at 11:48 AM |
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i think people usually talk crap anyway! very few people actually go to a rolling road, they just start at the manufacturers figures (flywheel i
guess) and then add on optimistic amounts for mods. like 5 for a filter, 15 for a decat etc. I put my vectra v6 on a rolling road once, it had less
than the claimed manufacturer figures even with the cat removed!
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Alez
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| posted on 16/4/04 at 12:45 PM |
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Jasper: ab so lu te ly, it's a man thing!! Nah, the subject just came to my mind when I read about the 3.8 kg / bhp the new BMW M3 CSL
has, it's just too close to the standard Locost Blade, only the M3 is like 10 times the cost 
Cheers.
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Mix
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| posted on 16/4/04 at 03:03 PM |
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EU
OK, so when did they move Guildford from Surrey to Spain ???
Mick
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ned
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| posted on 16/4/04 at 03:41 PM |
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since alez forgot to update his profile i guess 
Ned.
beware, I've got yellow skin
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NS Dev
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| posted on 16/4/04 at 10:28 PM |
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power to weight in the UK (road tests etc etc) is usually quoted as flywheel BHP and metric (1000kg) tonnes.
Wonder what my vauxhall XE locost will weigh?? 205hp, don't know the kgs though yet!!
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Alez
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| posted on 19/4/04 at 06:00 AM |
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Hmm, that gives the maximum possible figure of all rather than the most useful figure (performance related). It's like the nominal power that is
normally given by car amp manufacturers, maximum peak power instead of RMS and things like that, useless as a figure but gives a high value.
As for my moving.. oops!! I'll update my profile now
Cheers,
Alex
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Spyderman
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| posted on 19/4/04 at 06:13 PM |
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British industries have been using the same standards as the rest of Europe for decades now.
Power is usually stated as wheel and not flywheel.
The American use a different system again and quote flywheel power.
European DIN against USA SAE.
You will find variations across Europe as to how they interpret the power to weight, but it is always measured the same way. Or it should be!
Using the BHP/ton (tonne) is a carry over from the old imperial system as an imperial ton is similar to a metric tonne. It is just something that
sticks because you are accustomed to it!
Spyderman
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NS Dev
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| posted on 19/4/04 at 07:24 PM |
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sorry but the british motor industry does not quote power at the wheels, that is incorrect!! That wouold depend on tyre pressures, type of tyre
fitted, blah de blah. The power quoted (in the DIN spec) is the corrected dyno checked figure at the flywheel of an engine dressed as if in the car in
simple terms.
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