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Location:
Sydney
Registered:
May 2002
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Question: Push Delivery of AWD & 2WD ???
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Thu, 15 May 2003 07:44
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Hey all
A question ive had in my head that no one has been able to answer me properly yet has been in my mind lately.
As the title says…..the push delivery off AWD and 2WD
Lets disregard traction issues and weight issues….
Lets assume both cars have same traction, weight and driveline loss characteristics
And that the AWD is in a 50/50 front to rear power ratio
Now I want to know if a car with 100kw at 2 wheels will have the same push delivery as an AWD with 50 kw front and 50Kw rear … (assuming that in AWD cars the power splits up evenly like that in regards to the ratio ?) ..... by push delivery i mean will they both run the same quarter for example
Another way of thinking is a carriage with one horse pulling X amount of power…..or the same carriage with 2 horses pulling with 0.5X amount of power each
Another way……a power boat with a 100Kw engine……or 2 separate 50 Kw engines…
Now ive tried to make this question as clear as possible cause most ppl don’t quite understand what im saying
Any replies greatly appreciated
Now ive heard for example if u have a 100DB speaker…..and u add a second 100DB speaker……u only get a minimal increase in DB (DB = Decibel)….no where NEAR 200 DB
Also with my powerboat example above ….a mate told me today ….a second engine with the same power …only increases the power by 30% or something…
So judging by these 2 theories I assume it would also apply with my AWD, 2WD question ???
Any replys are much appreciated
Thanx
Mani
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Location:
Cabramatta, NSW
Registered:
May 2002
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Location:
Sydney
Registered:
May 2002
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Re: Question: Push Delivery of AWD & 2WD ???
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Thu, 15 May 2003 08:03
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I said above......"Lets assume both cars have same traction, weight and driveline loss characteristics"
Note .... Driveline loss characteristics are the same
Thanx
Mani
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Location:
Cabramatta, NSW
Registered:
May 2002
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 Re: Question: Push Delivery of AWD & 2WD ???
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Thu, 15 May 2003 08:11
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MKay... Well, with your examples, dB is a logarithmic scale, so things don't add linearly.
I'd imagine with powerboats that a second engine would increase things like drag and weight which would result in a detectable increase of less than the amount of power that you're adding. Same thing as the drivetrain losses.
One 100kW engine would be better than two 50kW engines because you're doubling up on the drivetrain losses too. Unless the engines were built straight onto the hubs (like electric motors in some cars).
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Location:
Sydney
Registered:
May 2002
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Location:
Sydney
Registered:
May 2002
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Registered:
May 2002
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Re: Question: Push Delivery of AWD & 2WD ???
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Thu, 15 May 2003 12:25
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hey uve lost the plot...
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Location:
Melbourne
Registered:
March 2003
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Location:
Darwin -> Perth
Registered:
May 2002
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I supported Toymods
Location:
Sydney
Registered:
June 2002
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Re: Question: Push Delivery of AWD & 2WD ???
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Fri, 16 May 2003 02:44
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what ive notice through my experiences is that 100Kw in a rwd car feel faster than in an awd car.
This is due to the awd push and pull action which makes it feel much more linear
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Location:
Sydney
Registered:
May 2002
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Re: Question: Push Delivery of AWD & 2WD ???
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Fri, 16 May 2003 08:00
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Thanx the last 3 ppl that posted
That cleared it up
so u DO understand where im getting at ???
Ta
Mani
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I supported Toymods
Location:
Perth
Registered:
May 2002
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Re: Question: Push Delivery of AWD & 2WD ???
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Fri, 16 May 2003 08:03
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All things equal like you said, including traction, they will be exactly the same, the product of power versus weight.
The irrelevance of the question comes in that, its not a real world question. The AWD car will have more traction, more weight and more driveline losses.
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Location:
Sydney
Registered:
May 2002
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Re: Question: Push Delivery of AWD & 2WD ???
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Fri, 16 May 2003 08:08
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thanx frank....... Frank im totally aware of that.....hence why i said disregard those factors.......im just trying to get my head around power from 2 areas and 1 area.....so i dont think its irrelevant
Ta
Mani
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Toymods Board Member
I supported Toymods
Location:
Turramurra, Sydney.
Registered:
May 2002
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Re: Question: Push Delivery of AWD & 2WD ???
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Fri, 16 May 2003 08:37
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Put it this way- 2 horses pulling a chariot (eg, a valiant  ) vs. 1 horse pushing & another pulling a second chariot.
If all things were equal they would go the same speed.
4WD advantages & disadvantages all comes down to grip & drivetrain loss (& expense).
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Location:
Sydney
Registered:
May 2002
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Re: Question: Push Delivery of AWD & 2WD ???
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Fri, 16 May 2003 08:58
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as long as u guys are sure about this and not guessing thats sweet
thanx for clearing it up
Ta
Mani
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Location:
Sydney
Registered:
June 2002
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Re: Question: Push Delivery of AWD & 2WD ???
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Fri, 16 May 2003 11:06
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wouldnt a wheel being driven by 50kw spin faster than one driven by 25kw?
i guess 2wd would be overall faster than 4wd if everything was the same and real world physics forgotten
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Location:
Sydney
Registered:
May 2002
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Re: Question: Push Delivery of AWD & 2WD ???
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Fri, 16 May 2003 11:11
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odd way of wording your sentence...but i see what your saying...Thats true.....a wheel with 50kw will spin faster than a wheel with 25kw......but we're talking about 4 wheels with 25kw each.... vs 2 wheels with 50 kw each.....pushing/pulling a car
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Location:
Sydney
Registered:
October 2002
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Re: Question: Push Delivery of AWD & 2WD ???
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Sat, 17 May 2003 03:58
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Are you still going on about this, Mani?
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Location:
Sydney
Registered:
May 2002
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Re: Question: Push Delivery of AWD & 2WD ???
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Sat, 17 May 2003 04:28
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No josh its im asking why the sky is blue
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Location:
Sydney
Registered:
June 2002
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Re: Question: Push Delivery of AWD & 2WD ???
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Sat, 17 May 2003 11:38
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ok point considered
4x25kw wheels
-vs-
2x50kw wheels
ok just for an example
a wheel driven by 25kw reaches a maximum speed of 3 revolutions per second
is it ok to say that a wheel driven by 50kw can reach a maximum speed of 6 revolutions per second?
if so then the 2x50kw will have a higher top speed
 right?
someone ask professor frink
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Location:
bris
Registered:
February 2003
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Re: Question: Push Delivery of AWD & 2WD ???
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Sat, 17 May 2003 11:59
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but the 4WD would have totally different take off becuase of different weight transfer issues...
your completely disregarding physics and a car like this would never be able to be built...
but... i'd imagine a car putting down 100kw, and a car putting down 100kW weighing the same would pull the same 1/4 times yes
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I supported Toymods
Location:
Epping, Sydney
Registered:
May 2002
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Re: Question: Push Delivery of AWD & 2WD ???
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Sat, 17 May 2003 12:25
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you guys makes things so complicated!
year 10 physics (as someone stated earlier on)
acceleration = power (force)/mass
very nice equation, which only applies to the physics fantasy world where air resistance and such dont exist.
like this one, where weight difference, drivetrain losses, and traction aren't an issue.
doesn't matter *at all* where or how the power is applied. it is all forcing the car in a forward direction, so the same amount of power forcing the car in the same direction produces the same acceleraion
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Location:
Sydney
Registered:
May 2002
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Re: Question: Push Delivery of AWD & 2WD ???
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Sun, 18 May 2003 02:22
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Strober power has very little to do with top speed ....and more to do with acceleration
I know this isnt entirely true but for my question lets put it that way
Draven that clears things up a bit
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Location:
Brisbane
Registered:
May 2002
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Re: Question: Push Delivery of AWD & 2WD ???
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Sun, 18 May 2003 09:57
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WTF? Power has a lot to do with top speed! Ignoring gearing issues, a vehicle's top speed is mainly determined by power and aerodynamic drag.
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Location:
Sydney
Registered:
May 2002
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I supported Toymods
Location:
Epping, Sydney
Registered:
May 2002
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Re: Question: Push Delivery of AWD & 2WD ???
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Sun, 18 May 2003 11:07
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ignoring real-world effects, top speed is unlimited (as it is in space vehicles, propelled in a vacuum). Well, nearly unlimited. In theory, as you approach the speed of light, you need more and more energy to produce acceleration due to the excitement of the atoms (and the debate about what happens once you reach the speed of light)
but those sort of speeds are a little out of the league of what our cars are capable of
or of what anything is capable of in atmospheric conditions 
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Location:
Cabramatta, NSW
Registered:
May 2002
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 Re: Question: Push Delivery of AWD & 2WD ???
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Mon, 19 May 2003 00:21
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Top speed is unlimited as long as you have an infinate amount of energy...
You'd also have to worry about the weight gain... 
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I supported Toymods
Location:
Perth
Registered:
August 2002
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Re: Question: Push Delivery of AWD & 2WD ???
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Mon, 19 May 2003 07:22
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having a wheel with 25kw and one with 50kw will not make it 'spin faster', it will just have a greater force behind it
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Location:
Melbourne
Registered:
March 2003
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Re: Question: Push Delivery of AWD & 2WD ???
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Mon, 19 May 2003 07:43
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speed is unlimited, its like saying that the sound barrier can't be broken. Its just a number, u can go faster than the speed of light. The mass does not increase, a=f/m.
In space, the mass will not increase. If you have the same amount of power pushing something forwards, it will continue to accelerate until its acted on by another force.
and its yr 11 physics now, not year 10
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Location:
Cabramatta, NSW
Registered:
May 2002
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Re: Question: Push Delivery of AWD & 2WD ???
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Mon, 19 May 2003 07:52
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I think you need to read up on some of Einstein's work...
As you approach the speed of light, you need more force, lengths get distorted, time slows, and weights increase.
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Location:
Cabramatta, NSW
Registered:
May 2002
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Location:
Melbourne
Registered:
March 2003
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Re: Question: Push Delivery of AWD & 2WD ???
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Mon, 19 May 2003 07:56
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It's all theory, just like einsteins universal constant...
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I supported Toymods
Location:
Epping, Sydney
Registered:
May 2002
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Re: Question: Push Delivery of AWD & 2WD ???
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Mon, 19 May 2003 11:22
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it is all theory
and some of the theories conflict
hence why I didn't bother going any further
and it really does get away from what is possible on earth
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Location:
Cabramatta, NSW
Registered:
May 2002
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Re: Question: Push Delivery of AWD & 2WD ???
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Tue, 20 May 2003 00:27
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Gravity is a theory too.
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Location:
Madrid - Spain
Registered:
August 2002
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Re: Question: Push Delivery of AWD & 2WD ???
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Tue, 20 May 2003 03:30
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If you want an Engineers opinion, I am happy to offer one.
Firstly I have to correct BigWorms statement, there is at least 300 horses pulling a valiant.
Secondly and this is getting back to the question at hand, if you ignore the losses/traction/weight etc, there is no difference. For that matter you could have 1 wheel. Where the 4wd is better is that it reduces the loads on the tyres, which means you can push more power into them.
A 4WD vehicle is only better than a 2WD when traction is a problem.
Having said this, suspension geometry plays a big part in delivering power to the tyres, but his is another topic all together.
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Location:
Sydney
Registered:
May 2002
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Re: Question: Push Delivery of AWD & 2WD ???
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Tue, 20 May 2003 11:17
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Thanx Gold28
Much appreciated
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Location:
Adelaide
Registered:
June 2002
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Re: Question: Push Delivery of AWD & 2WD ???
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Mon, 26 May 2003 05:26
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Engineers opinion #2-
If you consider the two horses problem, due to the fact that horses generally have steel horseshoes on, their traction is somewhat limited-and especially when considering the common surface on which horses pulling carts-that is cobblestones (most often wet as well you will agree as we are generally talking about the deep dark middle ages when it really rained quite alot), it really becomes quite difficult to assess as the horses are likely to slip long before their individual output reaches even 1/2 a kw (aboout .7 or so of a HP). Consider then that you would need to put the horses on a large open field to enable them to put out even close to a kw each (better traction)-then of course you need about 30 horses per end of the cart-which I'm sure you would agree increases the weight of the cart considerably. Consider also the fact that at any one time there may be a proportion of the horses (30 at each end) distracted by the fact that they are in a field of nice green grass and so not actually pulling with the normal level of power. (the number of distracted horses is directly proportional to the level of greeness of the grass) To make sure the number of horses pulling is 30 at anyone time (at each end) we must either increase the number of horses (as there are already 30 at each end and horses were rather expensive during the dark ages this should be considered unrealistic), or find someway to stop the horses being distracted by the grass. One possible option would be to have a small gibbon assigned to each horse to keep it's mind on the job-however given the low number of gibbons in europe during the middle ages this has to be considered dubious solution to the distracted horse issue. Of course with the gibbons comes another problem-that is that they will increase in weight in accordance with einsteins theory as the horses accelerate-causing the horses to sink into the green soggy field up to their knees-bringing the whole experiment to a standstill. Of course this is clearly a failre of logic when comparing the vehicle problem to distracted horses being ridden by gibbons during the dark ages. You should really go back and re-think the problem.
Seriously though-100 kw delivered to the road from 2 axles or one is irrelevant. As long as thje total power is 100kw (the power curves must also be identical as '100kw' simply denotes the peak power of the engine) and the mass of the vehicle is the same.
Or
If the area under the power curves for the the two smaller engines equals the area under the power curve for the larger engine then it will also make no difference.
(this is perhaps oversimplified as there are a few assumptions and statements to be made-but after that rubbish above, my typing finger is sore)
Oh yeah, and for the wheel discussion, 25 kw and 50 kw through the same wheel, the 50 kw will accelerate the wheel from a standstill to the designated revs in 1/2 the time. (note-however this does not mean that in the same time the 50 kw wheel will be doing twice the speed-remember Kinetic energy=1/2(mv^2))
Talking about 'neglecting losses' is a perfectly relevant way to get your head around things as it allows you to understand individual concepts rather than attempting to deal with several variables at once. It is similar to conducting an actual experiment under controlled conditions. Whilst it may not reflect 'real world conditions' it will illustrate actual relationships and is good experimental practice.
Sean
(PS : I am actually an engineer-despite what the above load of garbage my indicate…)
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Location:
Madrid - Spain
Registered:
August 2002
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Re: Question: Push Delivery of AWD & 2WD ???
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Mon, 26 May 2003 06:05
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So what your saying if I understany you correctly is that if we give each of the horses a couple of pairs of nike's and put them in a field wit no grass, we will have controlled conditions and that means that regardless of wether we have 30 GG's at each end or just 60 GG's at one end, it will get to the castle just as quick. 
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Location:
Sydney
Registered:
May 2002
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Re: Question: Push Delivery of AWD & 2WD ???
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Mon, 26 May 2003 08:21
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| MS-75 wrote on Mon, 26 May 2003 15:26 |
Talking about 'neglecting losses' is a perfectly relevant way to get your head around things as it allows you to understand individual concepts rather than attempting to deal with several variables at once. It is similar to conducting an actual experiment under controlled conditions. Whilst it may not reflect 'real world conditions' it will illustrate actual relationships and is good experimental practice.
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Thats exactly my point
Well done
Much appreciation for your reply
Ta
Mani
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Re: Question: Push Delivery of AWD & 2WD ???