RBYCC

The land speed record ( supersonic ) was set in the nineties and yet to be broken...

1990....lets go back even further as I've been an engineer since the sixties and have owned cars over the years that you are not even capable of dreaming about..
I forget more "technology" in a day then you've learned in your short and uneventful lifetime...

Physics 101 hasn't change in spite of what you think you're reading on a Miata website...

Kid you're no more then an insignificant little acne faced snot who through "technology" can do a web search and convince yourself that you know something....

You're not even a mature teen, as you act like your still connected to you mother's teat...
That's why you are the way you are....with your constant droning immature and insecure ramblings...
How ridiculous are your "When I grow up....yadda, yadda,yadda " comments..
You still ride a yellow school bus...

Join the military, get shot at, become a man and maybe you'll gain a bit of respect from society...

The only thing that you excel at is your lack of knowledge compared to your age and the ability to act in a manner that is border line mental patient...

Man up ( doubtful ) and tell us all what you've ever done with anything mechanical in your life...
You don't even know how to change oil in your car, let alone tear down and rebuild an engine....

No more then a young loser who will go on to be an old loser...

RBYCC

Brett

You're a young man who I respect..
You've taken a lot over the years from many on this forum, but still looked to gain knowledge...

Respect can only be gotten by showing it to others..

Zach will never comprehend such a basic concept required to be a part of society..
Why..because he knows it all....

neanderthal

What if they lower it 2 inches and add a six speed.....

You've just contradicted yourself. Adding weight will affect top speed. PERIOD. Whether it's minimal or not is irrelevant.

the_widebody

^this quote is 100% correct^

and if the frontal area or cd are lowered, the same car will indeed go faster

so some of what the op is saying is indeed correct.

i saw a program and have also read about the early land speed record attempts, and this point was stressed over and over again.

the early cars were weighted down deliberately, they still reached the same speeds, it was improvements in aerodynamics and more power that increased the limits

the extra weight will mean it takes longer to get there, but it will still reach the same speed.

typical of certain members on hear to shout people down, and use 'fact' that everyone else agrees with, but then turn out to be 'not facts'

dont worry zach, there arguments against you will change as you start to prove your points, or they will just shout louder, and quote how many cars they own, or how shiny there **** is...

the_widebody

hears a question for the board especially the 'engineers' on hear (lol)

why hasnt the person who holds the land speed record just shaved a few pounds off the car they did it in, and gone faster? in fact, **** it, just loose half the weight, and they can go much faster, right?

answer - no

reason...


























because making the car lighter wont make it go any faster haha



hears a little thing i just found, note the emphasis i have put on weight and lenght of track, because the engineer has a short attention span, and will probbably miss this point

The Aussie Invader 5R is a rocket car that is intended to push the record way beyond Thrust SSC’s just-supersonic mark: like the BLOODHOUND Project, Rosco is aiming for a 1000 mph, and he is well on with building the chassis of this near-10 tonne car (a similar weight to Thrust SSC). This is the heaviest of the cars out there and means that Rosco will need a longer track to run it – he is still searching for the ideal record location.


surly he would just make it lighter if that would help?


no, the only thing weight affects is rate of acceleration

In drag racing, (wich our engineer has aparently done loads of) it is power to weight ratio which typically determines your performance.

When the track is very long, and your vehicle spends much more time at high speed,as in when trying for vmax it is power to drag ratio which is more important.

the weight only affects the power needed to get the thing rolling from a stop, like when you start off on a bike, it is hard to peddle up to speed, but once you are there is is easier to keep the speed going. if you had a weight strapped to you, it would be harder to start off, and take longer to reach your top speed, but it would defiantly be the same top speed.

it is aerodynamic drag or wind resistance that affects top speed.

the higher the speed, the larger the aerodynamic component of overall drag and the vehicles weight will become insignificant in the equation, just like delta x does in differentiation.

this quote is taken from a web site that is involved with land speed records, and i haven't altered it at all;

To truly understand all the things which affect “real world” top speed performance, you need a vehicle simulation programs like Drag Race Analyzer or Drag Race Analyzer Pro which lets you modify things like we’ve talked about, which include:

Actual engine power curve through entire RPM range
Drag coefficient and frontal area (and possibly lift coefficient).
Transmission and final drive ratio
Hood scoop efficiency
Tire type (to estimate rolling resistance)
Track length
Shift RPMs and shift type (fast, slow, power shift, etc).

does it mention weight?

no

zach1328

The Widebody:
Thank you for backing me up on this one.

I have read plenty of information that says and explains that weight does not have a big impact on top speed.
The only way it does affect top speed is if you run out of road. Ofcourse more weight will affect the acceleration times.

Assuming the conditions are the same:
Lets say a 3000 pound car can reach its top speed of 150mph in 55 seconds.
Take the same exact car but add 1000 pounds to it and it should still reach its 150 mph top speed, but instead will take it 65 seconds and much more road.

If weight had a significant affect on top speed, then why did the thrust SSC weigh over 10 tons? I'm sure the designers could have cut back on a little bit of weigh if they so desired, but it didn't matter enough.
At 150mph+ there are sooo many other factors that are going to matter much more than the vehicles weight.

Don't just assume I'm wrong all the time. I've done the research and I know what I'm talking about for SOME of this stuff.
And I'm the kind of person that isn't going to back down unless you can show me 100% evidence that my theory is incorrect.

EDIT:
RBYCC- You always talk about what kind of cars you have and what you've owned etc. You seem to be full of yourself, you are the reason 1/2 of the people on the W124 forum have improper information. They think that you know everything with your engineering background.

But you don't. This isn't the first time I have witnessed you post information that is not correct, yet you do a good job at making people think you're right.

As for owning cars I can't dream about, I don't even know what to say about that... I know some self-made people in my area that are 1/2 your age and driving cars that they bought for 2-3x the price of your black series. Yes, you're black series is nice, but I've seen better.

Shoomakan

I assume power/weight ratio? The Thrust SSC has thousands of horsepower, no?

Let's stop being drawn to more and more theoretical subjects.

A stock 500E will not, and can not, attain 300mph on shorter gearing, longer gearing, being dropped or being more aerodynamic. All those factors put together will make it faster, but not 30mph faster.

Can we close the subject now, please? I can't believe we're still wasting away our fingers trying to convince this kid.

Shoomakan

Oh and about the Thrust SSC... If they made it smaller, where would they put the fuel? :P

zach1328

Who said they have to make it smaller to make it lighter? Yes that would help but there are plenty of other ways to reduce the weight.

As for closing the subject, I would like to help you guys realize that 180mph is possible in a 500e with a 6 speed manual transmission and a lowering kit.

A 500e is drag limited to about 175mph. With an extra 2 gears, 10 RWHP, and a lower CdA and Cd, there is no doubt in my mind it can go the extra 5 MPH up to 180.

The factory tested one up to 175mph with just different gearing. And with those mods I mentioned I think you could grab the extra 5MPH, ESPECIALLY in the proper conditions.

Now to close the subject, I suppose my theory doesn't really matter because how often will anyone on here have their 500e up to those kinds of speeds? And the difference in 175mph and 180mph isn't that big.

The comment to end the dispute:
No matter what the actual top speed can be, I would say the known 165mph top speed is PLENTY for a 20 year old sedan.
Even some modern day performance cars struggle to get much more, so I'm happy with 165

the_widebody

the only problem with this shoomaken, is that power to weight ratio does not affect the top speed, it affects acceleration.

power to drag ratio affects top speed, and making the car lighter wouldnt affect the drag ratio, wich is why the top speeders dont bother with weight reduction

and tellingly, if you had read my post ^ and understood it, you would know this already.


those among us who claim to be engineers but can only resort to attacking people whom dont agree with them, and whom also have short attention spans would be advised to read the following many times before they come back with some abusive answer

imagine a car that weighs 1000 lbs and has 100 hp and has aero dynamics of a house, it will have a drag limited top speed and the following power to weight ratio (1000/100 = 10lbs per hp) its cd is say, 50

dont change anything to do with aero, but add a turbo and the associated parts to make the turbo work, it is going to be faster, right?

the pdf below is a formula to calculate the power to overcome aero dynamic drag, tellingly it doesnt caontain any variable relating to weight or mass.

imagine that the turbo and the associated parts had altered the power to weight ratio, because it now might made 150 hp and only weighed 100 lbs more. (1100/150 = 7.3lbs per hp)

now it would accelerate faster, as it has a higher power to weight ratio, and crucially may have a higher top speed, if the extra 50 hp was enough to over come the drag that was limiting top speed, because its cd is still 50.


now the thing is, if the kit had weight 500lbs, the cars power to weight would not have changed (1500/150 = 10) so it would accelerate at the same speed as it did before the kit was fitted, but may overcome the drag restriction, and go on to achive a highter speed, if the extra 50 hp was enough to over come the drag that was limiting top speed, because its cd is still 50.

now take the same car, with the heavy turbo kit and a higher power to drag ratio, and fit say a nose cone like the mk 2 escort rs2000 or the droop snoot firenza had... it would weigh even more, say 200 lbs for the areo parts.

now you have a power to weigh ratio of (1700/150 = 11.3lbs per hp)

it would now have a higher top speed, as the power to drag ratio would be lower.

but ****, it weighs more, so fit the nose cone on the lighter turbo kitted car?

ok, when you did that, it would not go any faster top speed than when fitted to the heavy turbo kitted car, because it still has the same power to drag ratio at the limit...

Shoomakan

Let's just leave the subject be, buddy... We won't know till someone tries.

RBYCC

Nick, Nick, Nick...
I so enjoy your challenges as they are most times not well thought out...especially when you contradict yourself

Appreciate your long treatise and yes the power to drag ratio is a major factor.

I don't believe, I ever mentioned power to weight ratio except in the example of a large diesel locomotive weighing 197 tons....which was meant in sarcasm to the OP..and even in this absurd example the heavy weight even with 5000HP precludes acceleration to reach any kind of high top speed...
Remember to consider frictional losses of which a heavier object has more due to added weight on the wheel bearings and tires...
Something that any theoretical calculation considers.

But let's use common sense and agree that you don't have an infinite distance to attain top speed...Bonneville is only five miles long !!
To get the optimum top speed, you want to get to top speed quickly, by optimizing acceleration at all times. This gets back to the drag race idea as weight will have a major impact on acceleration.
Yes vehicle weight alone is not a factor, but the power to weight ratio is a major factor in realizing top speed.
Try to use common sense and logic which you oft times miss in your long rants...

Decrease the power of a Veyron by one half, weight and aerodynamics remain the same and it will never achieve the top speed as with the original power output.

Lets consider the Nascar "restrictor plate"..The device limits the power output of the motor, hence slowing both the acceleration and the overall top speed obtainable on the tracks where the cars are so equipped !!!

My original comment to simplify all that is needed in the "top speed equation" was.." that to go twice as fast, you need eight (8) times the power "
If you want to get into Bernoulli, then let's go for it...I've accomplished more then just reading as you as I've applied theory for many years in the real world...

If you go back to the initial responses you will see that the comments on the 500E is that it does not have enough horsepower in stock form to attain the same speed that the "Hammer" did considering the Hammer had a .25Cd much lower then the 500E...and this still comes down to the power to weight ratio

Now to finish off the "snorting bull" using his own words as an estoca for the ultimate "coup de grace" :

"None is so blind as one who will not see"

And Nick boldly said "no" to weight from the web site he referenced as the "authority".
But yet Nick in his irrational exuberance failed to open the link which better describes the software...
Again proving Nick's lack of basic knowledge and consistently not able to apply logic and common sense in the undisputable fact ( Physics 101 ) that weight is a major factor in calculating speed and time.

And yes "weight" must be plugged in prior to the software making any other calculations...

http://performancetrends.com/drag_racing_analyzer.htm

Appears that the software developer gets even more finite with the "weight" factor that Nick and Zach in their immature and inexperienced conclusions determine as negligible...

"The Drag Racing Analyzer has always had more detailed inputs than other programs: things like headwind, weight distribution, differential locking efficiency, front and rear wheel/tire weight (analyze rotating inertia effects), Front vs Rear vs All wheel drive inputs, drag coefficient and frontal area, shift times and shift % throttle, computer optimized vs user defined launch specs like throttle and clutch factors.
-Weight Calculator lets you estimate the weight of several popular body styles."

Another case of a "Google Genius" that reads but cannot comprehend...
No different then the fool that Zach makes of himself and the perfect example of a young fool getting more foolish with age...

And to put it in your typical large mental patient post ending:

Check....and Check mate.....you've been served

the_widebody

because the power to drag ratio would be changed for the worse, lol, as usual you havent actually understood the issue i am making.

conversely, leave the power the same, and lower the drag, and it would go faster, because the power to drag ratio would be changed for the better.

answer this, why did they not just reduce the weight of the land speed record car, and therby increase its top speed?

lightening the car alters the drag in the bearings and tire contact infinitesimally, as it approaches the limit, it makes no difference.

weight distribution, which you have highlighted will only alter lift characteristics and therefore parasitical friction, ie drag, or power distribution, ie acceleration.

when it comes to top speed we are talking about fluid dynamics (air acts like a fluid at high speed)

i didn't bother linking the software because having looked at it, it doesn't show that lower weight will allow for higher top speed. it doesn't say it because it doesn't affect it, obviously, if it does you will be able to show me where the software shows lower weight allows for higher top speed.


because the software calculates other things than top speed, like acceleration and deceleration, which are governed by weight, including the weight of the wheels, wich again only affects changes in speed, not the out right ultimate speed.

there's no fool like an old fool, and you be the oldest, and the most foolish;




you say you never mentioned the power to weight ratio being the desiding factor on top speed?

well hear you did;
no it doesn't the ratio of power to cd is the power to drag ratio, if you lowered any cars cd it would increase its top speed, go read my example above, and try to actually understand it.

guess what, this device alters speed and acceleration because it lowers power, it does nothing to the cd, so by association if the power goes down and all other variables stay the same it lowers the power to weight ratio (so lowering acceleration) and it also reduces the power to drag ratio(so cutting speed), dam, you really showing your massive understanding on this one (not).

sorry old fool, but you are confusing two formulas, the one with weight in it, relating to acceleration, in this formula;

a = F/m,

where F is the net force applied to a mass, m.

Acceleration is also the change in velocity, (Delta-V), divided by the change in time, (Delta-t). So, a = Δv/Δt.

so, there you go again, quoting 'fact' that you don't actually understand, thereby making non facts which confuse your followers;

you are almost using the correct formula so i will try to help you out.


ok, this must be hard for you to understand so concentrate, speed and time are related only in terms of;

speed =distance/time,

distance = speed * time

time = distance /speed




now, in those equations, can you see a varable that indicates weight, or mass?

try to concentate now, i know you can do this...















































ok, you cant, i'll help you, no there isnt one for mass or weight.



so back to the real world things that effect top speed;

now the hint is in the title of the list i quoted earlier, i will write them again,in red, with the title in blue;

To truly understand all the things which affect “real world” top speed performance, you need a vehicle simulation programs like Drag Race Analyzer or Drag Race Analyzer Pro which lets you modify things like we’ve talked about, which include:


Actual engine power curve through entire RPM range
Drag coefficient and frontal area (and possibly lift coefficient).
Transmission and final drive ratio
Hood scoop efficiency
Tire type (to estimate rolling resistance)
Track length
Shift RPMs and shift type (fast, slow, power shift, etc).

if weight was one of the influencing factors in top speed, it would be in the list of things that effect top speed...













i realized long ago that i am having a battle of wits with an adversary who is unarmed.

neanderthal

speed= distance/ time doesn't include mass because it's the formula for deriving speed, given distance and time. It's not the formula for deriving top speed, for which you would have to use other metrics.


Just because you can pull a rope, doesn't mean you can push it.

Information is useless without the knowledge to apply it.

whipplem104

You guys should search the internet. There are actually formulas although rough for figuring out the hp top speed of a vehicle with given cd and frontal sqft.

the_widebody

ok, you can all bring and come, coz i aint gonna back down on this;

ed was atempting to say that weight was a major factor in determining speed and time, and by association infering that the speed was vmax.

I hadent seen a formula with weight, speed and time in it, but have found this;

the folowing two examples show that weight plays very little difference in terminal velocity(remember delta x?), it just means that increased weight would mean it would take a longer distance to achieve top speed, as in this formula;

Force = 1/2*CdA*p*v^2 + CrW


Cd = Coefficient of drag


Cr = Coefficient of rolling resistance for vehicle.

p = Density of air

A = Cross sectional area of the car

W = Weight of the car

v = Velocity.

air drag increases by he square of velocity, the part involving weight is independent of velocity.

so, to repete, increased weight will make a negligible difference to cr, and cr is not the limiting factor on top speed of cars

extra weight would just mean it would take a longer distance to achieve top speed for a heavier vehicle with the same power and same cd


================================================== ================================================== ========================

another way of deriving top speed is v = P/F

v: Velocity
P: Power (more power is more top speed)
F: Friction (more friction is less top speed)

On level ground, there will be two main frictional forces that the power of the engine (force) need to overcome. Internal (in the bearings, and obviously the wheel contact patches, etc), and air drag.

Friction due to air drag is expressed as Fd = Cd(pv^2/2)A

Where
Cd: Coefficient of drag
p: Density of fluid
v: Velocity
A: Frontal area of the car

there is no mention of car weight in this entire formula.

Internal friction is constant independent of velocity, but will rise a negligible amount with increased car weight, but isnt the limiting factor.

RHW

the_widebody

and irrespective of all the above, the fact that persons undertaking speed record attempts dont rely on reducing weight,because it doesn't help them, is the best evidence in support.

the_widebody

correct, and the issue was the engineer bad mouthing a young lad who thought that lowering the frontal area of a car by removing wing mirrors, lowering it and fitting skinny tires would increase its top speed.

the young lad was correct.

the engineer then started saying the car in question was too heavy to reach a theoretical speed, and now hear we are, showing him that weight isnt the issue.

zach1328

I was going to stop posting on this thread but now the Bullsh** has gone too far and this needs to come to a final conclusion.

The widebody has supported his theory and my theory on the affect of weight and top speed with both valid formulas and real life examples.
Yet people are still disagreeing (mostly Ed) and do not have valid information, formulas, or any kind of evidence to support their thought.

You're not going to win an arguement by simply stating what you think. If it is true that weight affects top speed (I already know it doesn't) then show us why you think that.

I'm just interested to hear why you think weight has a big impact on top speed.

neanderthal

I'll try to keep this simple. No formulas, no science.


Inertia is a body's resistance to a change in state or motion. It follows then, that to effect change on a body, one must apply an outside power. A car (object) needs power (the outside force) to accelerate. This is true if it's a Tonka, 500E, or the Thrust SSC. I'm pretty sure there is no disagreement so far.

A bigger or heavier object will require more power to accelerate. Essentially, mass adds resistance.

Drag will slow down an object. Mechanical and air drag will contribute to slow and eventually stop the object once the outside force is removed.

Mechanical drag and air drag exist in the realm in question.


If you are at the limits of air drag, given a sum of force, you will no longer accelerate. You must add more force to keep accelerating.

If your object, given a fixed force, is given additional mass, it'll require more force to maintain it's acceleration, but some force is used to overcome the additional mass, therefore it'll not achieve it's terminal speed.


The theories that mass doesn't affect top speed usually stipulate that it does, but it does so minimally.

I say, if adding a thousand kilograms will definitely affect top speed, all else being the same, then 3 grams will affect top speed; you just have to go far enough with the decimal places to observe the effect.

Ergo, mass affects top speed.

Shoomakan

A neanderthal you are not.

ptoro01

How about a diff rear diff while we are playing with gearing.

RBYCC

Nick

Once again you speak of that which you can't comprehend...

The effect of weight is minimized the faster you go as you correctly posted.
However if you again look at the software that you nominate as the "authority", you can't do any calculations without entering a weight.

As difficult as it may be for you apply common sense and logic my young misdirected lad...how do you ever get to a top speed that is effected by aerodynamics without starting out by accelerating a mass ?

Obvious you and Zach think along the same illogical lines and really have no knowledge of other then what you cut and paste from websites....

Looks like the man who took a pedigree and turned it into a mutt again comes out on the short end with his supposed knowledge..

Enjoy your challenges but getting boring dealing with an adversary that is not competent in the subject at hand !!

I do find you extremely humorous, especially your inability to spell and construct a proper sentence..

RBYCC

I linked the calculators in my post #8 on this topic...
Even with the simplicity of the calculators, both Zach and Nick deny the fact that a stock 500E can't attain 180+mph...

Modify it and attain a Cd of .25 like the Hammer and add about 75HP + and it may stand a chance...

Horsepower does matter ...