What's the top speed on your car?

[LX5liter]

One more thing to add to the " human with 50 lbs on his back " factor is fatigue. Engines won't experience this in one high speed run. ( they will over time though, Its called wearing out! )

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B.R.
L.X. 5.0 coupe
Cruise control,power mirrors,...and Thats it!

[PKRWUD]

My '77 403 LeSabre w/ 2.83's &
L60's pegged out the 160 speedo, but that was a few years ago.

Take care
~Chris

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Retired Moderator
MustangNet

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[MiracleMax]

Originally posted by dinomite:
Aerodynamics is a bigger factor than weight in top speed, but think of it this way: What is *your* top speed? now put on a 50 lb. backpack.....

Assuming that the backpack didn't alter my aerodynamic profile then I would still be just as fast but not as long if I were unladen

Your analogy is correct if your are indicating it takes a certain amount of power to maintain a particular rate of acceleration.

Throw your buddy in the car with you and you'll still have the same terminal velocity although it will take you longer to get there, throw him on the roof, and not only will it take you longer to get there, but you will also slow down (unless screaming buddies have some aerodynamic enhancing property not known to modern science )

[82 GT]

stang runner, that 5200rpm was with an autometer tach.
I was hauling a$$
It took a long time to get stopped too...wow!

[NO SLO PK]

Originally posted by Unit 5302:
Of course, drag and hp are really the main factors, gearing plays into the hp part.

Gotta agree with Unit. What determines your top speed is drag, which is a combination of aerodynamics and friction. Aero drag increases exponentially with speed, so aero drag is the biggest factor that determines how fast you can go.

More weight might may mean more rolling friction, but it has minimal effect on top speed. It just takes longer for the heavier vehicle to get to terminal velocity.

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Russ L
'91 LX
Procharger, 3 row intercooler, extrude honed Cobra intake, Mac full Length Headers, 30# inj., 73mm C&L, 75mm tb, E303 cam, 289 rods, ported E7 heads, MSD, T-Rex w/255 lph Walbro, 5 lug conversion, Cobra R wheels, 3.27 gears and Moser Axles.

[dinomite]

i'm not saying that it has a big effect, just that it does have an effect. if you don't trust me, go ask your college physics professor. i knew that the backpack thing was a bad analogy, just trying to get my point across.

[95mustanggt]

Originally posted by dinomite:
Aerodynamics is a bigger factor than weight in top speed, but think of it this way: What is *your* top speed? now put on a 50 lb. backpack.....

Incorrect. If you look at the physics in running, your legs must "push" your body up and forward. Completely different force diagram.

Weight has little to do with top speed. Although I guess if you got real picky you could argue that a higher downward force would contribute to higher frictional forces which would lower your top speed. But then again, the same would be true if you put on wider tires, softer rubber tires, etc.

Unit has the correct analysis here.

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1995 Mustang GT

[BilLster]

ok lets try this go to the top of a very steep hill now run down .drive ride take you time getting up be well rested put that 50lbs on now run down which will be faster ? my geuss me falling with the 50 lbs.


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89 with 395 single stage n2o .garret t3. 373's Suspention worked out finnaly . need cage .

[John]

drag smag, he just wanted to know top speed of our vehicles, and if he has a limiter on his. chill pill time for some of us, i've had mine to 135 with more to go, that was fast enough for me 4:10's stock suspension 235/60/15 BTW isnt drag some rope sucker dressed in girls clothes

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89 Notch: ASP Pullies,
K&N Air,Transgo shiftkit,Trans. cooler,FMS 3 core Radiator, FMS 4:10's, 1.5" cowl, cold air kit, hooker equal length shorties(jet hot coated), O/R H-Pipe, ASP solid mounts, Energy Sus. Trans. Mnt. BBK 70mm TB, MSD 6al, Dual elec. fans

[RED92LX50]

According to my stock speedo, I was going just under the 140 mark (maybe 137) and could go no faster - I was in 5th gear and had been accelerating for about 3 miles chasing a buddy on a motorcycle (I did not catch him!). As for the limiter question, you probably don't have one, but even if you did, I don't see why you would need to remove it unless you found yourself hitting it.

[jimberg]

Top speed has everything to do with the mass of your car. In order to reach top speed, you need to generate enough force to accelerate the mass of your vehicle to that velocity. Force = Mass x Acceleration.

Let's say that your engine can generate a constant force, which it can't do. The mass of your vehicle will remain constant. As the velocity of your vehicle increases, the force of drag on your vehicle will increase (quadruples for every time the velocity doubles). The force of drag can be subtracted from the force your engine is able to generate and then you can divide it by your mass to determine the rate of acceleration. Your acceleration will constantly decrease until, for all intents and purposes, it reaches zero.

Now factor in the fact that engines don't generate a constant force and force drops off significantly at higher RPMs.

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351W 89 Mustang GT Convertible

[This message has been edited by jimberg (edited 07-23-2001).]

[82 GT]

Actually, it doesn't really matter how fast your car can go. A better question would be "How fast can you drive?"
A car that can go 200mph means nothing if you don't have the guts or experience to drive that fast....correct me if I am wrong.
Most people wouldn't be able to just hop into a Winston cup stock car and expect to go 200mph.
These peolpe that buy these corvetts, Ferrari's and Porche's and brag about how fast their car is clocked at cracks me up!
Let see those guys get out there and drive that fast. My money says a majority of them won't have the balls to go much faster then 140-150 if even that fast.


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'82 GT 351W C-4,BBK headers,Carter 625 carb,Comp.Cam,Flowmaster exhaust.
1988 GT...T-5,bone stock

[dinomite]

Originally posted by John:
BTW isnt drag some rope sucker dressed in girls clothes

lol! they have drag races of that type in dc.

[NO SLO PK]

Originally posted by jimberg:
Top speed has everything to do with the mass of your car. In order to reach top speed, you need to generate enough force to accelerate the mass of your vehicle to that velocity. Force = Mass x Acceleration.

Let's say that your engine can generate a constant force, which it can't do. The mass of your vehicle will remain constant. As the velocity of your vehicle increases, the force of drag on your vehicle will increase (quadruples for every time the velocity doubles). The force of drag can be subtracted from the force your engine is able to generate and then you can divide it by your mass to determine the rate of acceleration. Your acceleration will constantly decrease until, for all intents and purposes, it reaches zero.

Now factor in the fact that engines don't generate a constant force and force drops off significantly at higher RPMs.

Actually, according to the equation above, top speed is not determined by mass. According to force = mass x acceleration, two cars of different mass will reach the same top speed, all else being equal. The main difference is that the car with greater mass will take more time.

With a greater mass, acceleration is less. But the car will still accelerate until the power it delivers (force) equals the forces of aero drag + friction.


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Russ L
'91 LX
Procharger, 3 row intercooler, extrude honed Cobra intake, Mac full Length Headers, 30# inj., 73mm C&L, 75mm tb, E303 cam, 289 rods, ported E7 heads, MSD, T-Rex w/255 lph Walbro, 5 lug conversion, Cobra R wheels, 3.27 gears and Moser Axles.

[jimberg]

Yeah, you're right. Sorry about that. I realized that when I thought about it more on the way home. But hey, it settled the argument. Weight has nothing to do with top speed.

The backpack of weight argument is more akin to that of a parachute. Yes, if you add more weight to a parachute it will fall faster but that's because the added mass times the acceleration of gravity creates more force which in turn would create a higher terminal velocity.



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351W 89 Mustang GT Convertible

[BlackFly]

i really dont want to carry this thing on but yes there is a governer on your car , if you have a 5 sp then its a two wire connector on top of the trans , its tripped by fifth gear , it limits the revs to 3800 in fifth , the other gears are only limited by the rev limiter of 6250. pull the connector off and have at it.

[MiracleMax]

Originally posted by jimberg:
The mass of your vehicle will remain constant.

I was under the assumption that mass increased as velocity increased and this ties in with the theory of relativity (all joking aside), hence the super destructive power of meteors, asteriods, ect

but I digress

I can see where drag/friction limits top speed, and the relativistic effects of accelerating the mass from one velocity to another would support the statement that mass is a limiting factor,

however it seems to me that the speed attainable by most if not all vehicles niether have the mass or the speed to make mass by itself a consideration in limiting the top speed of the vehicle (hope that sounds right?) and aerodynamic forces (drag/friction) ultimately play the greatest role in limiting the top speed of a vehicle?

[jimberg]

MiracleMax, yeah, you had it right to begin with. Mass has nothing to do with top speed. It only determines the time that it takes to reach top speed.

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351W 89 Mustang GT Convertible

[MiracleMax]

Well I gave the mass/velocity statement a thought, If say for instance your car was able to operate in a vaccum, and had unlimited gearing so that engine speed nor drag was an issue, then eventually the relativisitc mass of the vehicle would become so high, the power produced by the engine would be unable to accelerate the vehicle from one velocity to another. Making the statement true in the that mass does have an effect on terminal velocity, but only in the relativisitic sense.

On a more practical level a car or any car is unable to generate suffcient velocity through gearing or power, for mass to have a substantial effect on terminal velocity. Hence aerodynamic forces (drag/friction) are the limiting factor here on terra firma.

I never dabled with physics in school, so I can't say if newtonian physics indicated an increase in mass as speed increased, but instead held mass as a constant depite the velocity of the vehicle.

[blueneonman1]

I've had my stock '95 gt with 3:08's and 245/45's at 141 and it would go much higher than that, but due to the wind that day, th car was taking flight. I want to top out my car again when I get fresh ZR tires. Does anyone know if the SN95's computer limits top speed?

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