top speed

[TG]

Some cars are designed to do that, my old '92 VR4 does that (160) easily,
keeps pulling right up to redline and will even do so without the turbos. I
think some cars that look aerodynamic may not be and some that look slow
might be capable....wind tunnel time pays off. Not sure about the Subarus
but all of the wind noise makes me wonder if they are less "slippery" My VR4
is silent, even with the windows down. TG

 

[TG]

That's easy enough to change. TG

 

[Bruce Hoult]

Jim is exactly dead on in his explanation of what causes any vehicle to
hit a limit of speed. As a matter of fact if you dropped it out of an
airplane you would hit a limit of how fast it would fall. Sky divers
refer to it as terminal velocity and depending on the shape every
object has a terminal velocity.

It's true that a given shape with a given amount of power behind it will
have a fixed top speed. But add more power and it will *always* go
faster.

I don't know how fast a WRX will go if you drop it out of an aeroplane,
but I do know that it will go a lot faster if you fill the cabin with
water first, and faster still if you fill it with lead.

 

[Bruce Hoult]

Nope.

The record was set by the 2l GT turbo, a car that unfortunately was
never sold in the US (you may notice on the linked page that the dude
with the helmet on is sitting on the "wrong" side).

But they're sold here in NZ

 

[Rob Munach]

The implication that there is a "terminal velocity" for a ground-based
vehicle is incorrect. Terminal velocity has very little to do with it.
Standard falling body terminal velocity is about 124mph. I hit that all the
time. However, the principle is similar: that which causes terminal
velocity is the same principle that dictates drag-based top speeds.




I hit 140 just the other day. It was easy. I just don't know what my STi's
*top* speed is, as I've never approached it and felt safe about it. Too
much wind around here buffeting me around the road.

The terminal velocity falling from a plane is a function of the
aerodymaics of the vehicle and mass. A human body, I believe, is about
120 mph. A car is going to be much faster as its weight to drag ratio is
much higher. A 3000lb car has 3000lbs of force pushing it thru the air
in free-fall. Horsepower = force*velocity (550ft-lbs/sec = 1
horsepower). At 150 mph (220 ft/sec), free fall, the force of gravity on
a 3000lb vehicle is generating 660,000 ft-lbs/sec or 1200 hp. If this
was the terminal velocity of the vehicle, the aerodymanic drag would be
burning up 1200 hp. This means if you took the same vehicle and put it
on the street and neglected all losses except aerodynamic drag, it would
take 1200 hp to go 150 mph. Since we know it probably would only take
300 hp to go this fast, the terminal velocity falling out of a plane
would be much higher than 150 mph.

 

[Bruce Hoult]

The terminal velocity falling from a plane is a function of the
aerodymaics of the vehicle and mass. A human body, I believe, is about
120 mph.

That's about right in the spread-eagle position with your body horizntal
and limbs extended.

Head first with arms by your sides and legs straight you do more like
200 mph.

 

[Carl 1 Lucky Texan]

I thought TV for a human was about 80 for either spread eagled with
floppy clothing or tumbling. Head down easily 120+. With streamlined
helmet and 'proper' position and spandex clothing I could see 180+.

Carl

 

[thestick]

There is an article in March '05 "Air&Space" magazine about a engineer
who skydives and clocks his pet falcon on the way down.

Spread eagle and horizontal terminal velocity is 120 mph. He began
"pulling in his arms and legs as experienced skydivers do"..."and soon
they were falling together at more than 240 mph."

 

[Rick Courtright]

75mph in MT

SoCal: weekdays, most daylight hours, maybe 25 mph?

Rick

 

[jbaker]

Jason

Your fast-autos.net was an interesting site.

Reading about the Subarus, the 2004 STI-WR1 had the fastest top speed
(155) at 320hp. I'll believe you that is controlled by the ECU. I
would argue that this is barely a 'stock' car, after all only 500 are
built. It is such an even number. A 2002 WRX had a top speed of 147
at 300hp and I find that in the realm of believability.

Now, compare that to the new 'Vettes. Very aerodynamically slick,
lighter in weight than a Subaru. They hit 190+ but they are also doing
it with an engine putting out 500hp or 166% of the power of a WRX
engine. That pretty well sums up the problem of high speed.
Aerodynamic forces build up with an inverse square ratio. It doesn't
just take more power to go faster, it takes a lot more power.

I am not trying to be difficult in this (well maybe I am, but there is
no malice in it), I just am having a trouble believing that stock
Subies (even with turbos) are regularly running over 150 mph. (I'm not
even sure about the driving skills needed to drive 150+ mph, but I
don't want to even start that discussion)

What would a new GT do with modifications to put out 450hp do, don't
know, but it wouldn't be stock.

Jack

 

[Carl 1 Lucky Texan]

Well, there is a guy with a big electric motor and the prop from a DC-3
(IIRC) that operates a vertical wind tunnel and rents folks a helmet and
some floppy clothes to walk out onto the wire mesh and 'float' on, again
IIRC, an 80 mph stream of air. Also, wind tunnel tests of hurricane
force indicate people can not remain standing above about 80-90 mph.

It does appear that VWT users were dissatisfied with early VWTs howvere
and now they operate around 120+ mph. A small person with a very big
'ballon suit' might have a TV around 80. I'd probably 200mph! hah!

check;
http://www.verticalwind.com/initial_airspeed.html

Carl

 

[The Gadget Shop]

Yeah, the WR1 was a 2004 UK limited release at 320BHP:
<http://www.import-heaven.net/specs_subaru_impreza_wrx_sti_wr1.shtml>

Petter Solberg uses it to do his grocery shopping in!
<http://www.seriouswheels.com/pics-2004/2004-Subaru-Impreza-WRX-STi-FA-Peter-Solberg-1024x768.jpg>

Certainly AFAIK stock STi will still hit the 155 mph limit, just take a
little longer. From personal experience, I doubt a stock WRX would - I have
been 125mph (200kmh) in a stock MY02 with some to spare, but I doubt there
would be another 30mph there... btw it felt amazingly stable at that speed -
next to no lift, just enough to lighten the steering. Ideally you'd have
better suspension and/or more of a front lip for stability.

I have been passenger in another car (6 cylinder Ford Falcon circa 1993)
doing 150mph (240kmh) and the car was floating like a hovercraft - scary as
hell and totally ridiculous to let such an unstable car reach that speed!
(they now speed limit them I think)

Cheers, Jason

 

[Ross Lyall]

Not to be difficult, I find 155 or 165 hard to believe, no matter how
powerful the engine. I would think the aerodynamic drag of the body
would limit it to something less than that. My Acura TL has an
aerodynamic drag limit of about 145 (not that it would actually go that
fast). I know that on the original Porsche 911's they had to do a lot
to the bodies to get over about 160.

IMHO I don't believe the WRX (or STI) bodies would be capable of doing
much over 140.

Believe it...

Ive had my type UK STi at over 150! Wasnt really interested in studying the
speedo to get the exact figure but my garmin gps said 151 was the highest
recorded speed.

Top speed of the PPP Type uk STi is not quoted but 160 or just a shad under
would sound about right.

Remember the Aerodynamics of the STi are probably pretty good, The newer
ones IIRC have a flat undertray (Like Ferrari) and the bodyshell is based on
the hugely successfull Subaru WRC. Im sure the guys at SWRT are spending
just as much time developing Aerodynamics as Porche are.

Ross

 

[Ross Lyall]

Certainly AFAIK stock STi will still hit the 155 mph limit, just take a
little longer. From personal experience, I doubt a stock WRX would - I
have
been 125mph (200kmh) in a stock MY02 with some to spare, but I doubt there
would be another 30mph there... btw it felt amazingly stable at that
speed -
next to no lift, just enough to lighten the steering. Ideally you'd have
better suspension and/or more of a front lip for stability.

Type UK Sti, is rock solid at 150, and the wipers still work!!!

R

 

[Ross Lyall]

http://www.fast-autos.net/list.html

Interesting Link, Noticed that the STi can stop from 60 in almost the same
distance as a Ferrari 360 Modena (110 vs 111 feet)

R

 

[k. ote]

Or what your girlfriend believes.

Oh, ow. Oh my goodness. I'm hurt. Spare me, God, from the amazing wit, the
panache, the razor-sharp tongue.. Ooo.. ow..

 

[k. ote]

I don't know how fast a WRX will go if you drop it out of an aeroplane,
but I do know that it will go a lot faster if you fill the cabin with
water first, and faster still if you fill it with lead.

That's not true. Your assumption here is that the limiting factor is the
friction between the tires and the road, and that once the top speed is
reached, attempting to go any faster will spin the tires, and thus more
weight is needed to increase the friction between the tires and the road.

The reality is that the aerodynamics of the car push back on the hard as
hard as the engine can push it forward, and it goes no faster. The tires
usually have nothing to do with it.

If we did fill the cabin with water, not only would the top speed decrease,
but the weight distribution would probably be screwed up, which may make it
more difficult to control at higher speeds.

 

[k. ote]

a 3000lb vehicle is generating 660,000 ft-lbs/sec or 1200 hp. If this
was the terminal velocity of the vehicle, the aerodymanic drag would be
burning up 1200 hp. This means if you took the same vehicle and put it
on the street and neglected all losses except aerodynamic drag, it would
take 1200 hp to go 150 mph. Since we know it probably would only take
300 hp to go this fast, the terminal velocity falling out of a plane
would be much higher than 150 mph.

Density has a lot to do with it, because density is usually a function of
volume. Also, average surface area which faces windward (down in the
falling case) at any point in time also has to be considered. Since there
is no anchor (i.e. tires touching the pavement) there is no clean way to
calculate the terminal velocity of a vehicle like the STi without actually
dropping one out of a plane or mostly destroying the STi's body in a wind
tunnel.

Anyway the point I was trying to make was that a falling body's terminal
velocity has very little to do with its top land-speed except that they are
related by the same underlying principle. Thus it's useless to consider
terminal velocity of a falling body when trying to consider its top
land-based speed.

 

[Florian Feuser /FFF/]

The terminal velocity falling from a plane is a function of the
aerodymaics of the vehicle and mass. A human body, I believe, is about
120 mph. A car is going to be much faster as its weight to drag ratio
is much higher. A 3000lb car has 3000lbs of force pushing it thru the
air in free-fall. Horsepower = force*velocity (550ft-lbs/sec = 1
horsepower). At 150 mph (220 ft/sec), free fall, the force of gravity
on a 3000lb vehicle is generating 660,000 ft-lbs/sec or 1200 hp. If
this was the terminal velocity of the vehicle, the aerodymanic drag
would be burning up 1200 hp. This means if you took the same vehicle
and put it on the street and neglected all losses except aerodynamic
drag, it would take 1200 hp to go 150 mph. Since we know it probably
would only take 300 hp to go this fast, the terminal velocity falling
out of a plane would be much higher than 150 mph.

Gravity accelerates bodies of different mass at the same rate.
The difference between a 3000lbs car and a falling feather is only
aerodynamic drag.

Are you saying it takes a 3000lbs automobile 1200hp to reach 150mph or
that the formula does not apply?

florian /FFF/

 

[John O]

Gravity accelerates bodies of different mass at the same rate.
The difference between a 3000lbs car and a falling feather is only
aerodynamic drag.

I was wondering how long it would take for someone to remember Newton.

-John O