How Is Top Speed Gained

[vetteeatr]

Hey guys i was curious as to aero dynamics and allt aht good stuff alogn with weight factors and horsepower needs.

Basically I want a car that can go over 200 MPH

I knwo this soudns pretty crazy but In reality you have to consider i think the new vettes top out at liek 180 MPH and they have something liek 350 horses.

Anyway I was wondering once oyur up and moving does weight really matter much if at all on your top speed?

The new lamborginis and what not are over 3k ibs and i was jsut wondering?

Now more importantly mustangs arent exactly aerodynamic how is this gonna effect thi.gs?

I actaully will probalyl be going with a 60's stang lowering it and adding a few mods to keep it on teh ground as much as possible but they are still somewhat brickish.

How many horses do you think i will need wiht a perfect combo wiht a T-5 tranny and ewhat rear end gears would oyu reccomend along with with tire size

[PKRWUD]

You would have to have 2.40 gears, or higher (numerically lower), a very stable frame, and an engine that could sustain 6250 rpms for prolonged periods of time.

You're looking at $30k in mods. to do it safely.

Take care,
ÅChris

[Jeff Chambers]

200mph in a street-prepped Fox body? Do you have a deathwish? :^)

Seriously though; the biggest hurdle in your quest is aerodynamics. The Fox Mustang has all the aerodynamics of a wet brick compared to a Ferrari, Vette or other supercar. Though a Mustang's .31 drag coefficient doesn't look that bad compared to a Ferrari's .23 drag coefficient (I'm not sure of the actual numbers here, just making them up to demonstrate the point), frictional drag is a function of the velocity SQUARED and frontal (projected) area. Any of the supercars (for lack of a better term) have a much smaller projected area than the Mustang. If I recall, the Fox has an area of something like 34 ft^2. I'd imagine that the Vette has something on the order of 24 ft^ max; very low slung profile. That's a factor of 1.42. Now since drag is a function of velocity squared, the amount of horsepower required to go from 120mph top speed to 200mph is about 2.78. Comparing that Vette's factory 350hp to a Mustang's stock 205hp, there a factor of 1.70. Multiply that 1.70 by the area advantage of 1.42 and the drag coefficient advantage of 1.34 and you've got a combined factor of 3.26 which pretty much says that the Vette can get upwards of that 200mph goal; and I haven't even figured in the differences in weight. Now if you go using a 60's platform Mustang, expect to need even more HP to reach that goal since they have an even worse drag coefficient and even more frontal area. There are many, many more factors such as parasitic drag (different than the primary frictional drag), ground effects, rotational inertia, on and on and on. If it were easy to build a 200mph street car, you'd see the pits at Indy and Daytona filled with Mustangs.

[MEDIK418]

THere's a guy running around the country doing roadraces who has hit a recorded 188 in a supercharged 97 Cobra that has a fairly stock block. Don't remember the name but the car does this a lot. He spins the thing to about 8,000 on occasion ( he claims) but I don't how high it revs at 188 mph in 5th gear. That's really close to that magical "two-oh-oh" but the drag on the car increases exponentially as the speed increases so he's probably farther from 200 than you might think.

[JohnnyG]

Are you talking about John Buscema's Cobra? He's been running in the Silver State Classic for years... there were a couple write-ups on him in MMFF or 5.0 Mustang a couple years back, I can't remember which. But he took the cup with fairly few mods for a guy running in the unlimited MPH class. What got me was that he was running 4.10 gears in that car... it must really love RPM!!!

I really don't know much about aerodynamics... just a VERY simple physics background... but I would think that three areas would need to be targeted:

1) Front chin
2) Rear underbelly
3) Rear wing

The front would need a bigger chin to increase downforce at the front wheels... also, all openings in the front should be sealed to create less drag (e.g. fog light ports, grille, etc.)

The rear underbelly (if that's even the correct term) would need to be smoothed out. With the GT, and even the LX bumper, you got to be pocketing a ton of air under there around the gas tank.. I'm kinda envisioning a smooth Fiberglass panel that covers that whole space over the gas tank and is integral with the rear bumper

Lastly the rear wing, obviously for increasing downforce at the driving wheels.

Guys please feel free to jump in and correct me if I'm wrong, like I said, I have no formal background in aerodynamics whatsoever, this is just what simple intuition tells me.

Oh yeah, one last thing... Balls!

-John

[vetteeatr]

Thanks Guys.

SO are you saying at like 180 MPH an dgoing up its a huge factor of aerodynamics? I really dont understadn the frontal area thing coudl you explain that again?

I know mustangs are bricks but lets say compared to a vette that has 450 RWHP and goes 201 MPH.

If I was to use a mustang platform how much RWHP woudl i actually need? 600? I mean honestly i knwo there are cars superior in certain aspects to the msutang. But its not a mustang.

Does weight play much a factor into top speed?

Actaully i plan to slightly lower my gears jsut a tad to maybe 3.08's but allow hte engine to rev around 7,000 or shouls i stick with my 2.73's or around there?

[Conman]

Originally posted by JohnnyG

Oh yeah, one last thing... Balls!

-John

hahaha
you need balls that clank

it could be done with a lot of work but I don't think the 60's stangs are even remotly a good place to start from.

as far as weight goes, it affects acceleration, NOT top speed.
it will a little bit but the difference between a 2500 lb car and a 3500 lb car would be negligable.

you would seriously need to work on aerodynamics and make sure EVERYTHING is balanced perfectly so that it doesn't vibrate you right off the road.

as far as frontal area goes, Stand in front of the car and look at it perfectly straight on. now ignore the 3-d and pretend it is just a 2-d image. The area of the car that you see is the frontal area. Notice that the roof line of ferrari's and corvettes is much lower to the ground and the car isn't much wider so the area is smaller.
one more thing is the smoother the contour from front to back, the less turbulence is created.

now for a little personal experience, I once did about 170 mph on a suzuki GSX-R 1100. The thing only had about 135 rwhp. Now the frontal area is tiny compared to a car and it had aftermarket fairings that were much improved over the stock ones. The sport bike is also very well balanced so there was hardly any vibrations but the wind force was INTENSE. I was scared and I felt way more safer on that bike at high speeds than a car at high speeds. I've never riden in a super car though so they are probably even better.

[vetteeatr]

Im sure im about ot get an *** chewing for this but what abotu lets say a fiero for starters. Eventually get a kit car body modeled after one of these aerodynamically superior cars?

These are some tiny cars and you can put V-8's in them and actaulyl suppsoedly use a porsche transaxle that can take some punishment.

What about that plan???

Im assumign the frontal area would be alto less for a fiero and with a kit body on it it woudl be near identical to the supercars drag right?

[PKRWUD]

Just buy a plane and put the wings on upside down.



Take care,
ÅChris

[HotRoddin]

Originally posted by jeff chambers
Now since drag is a function of velocity squared, the amount of horsepower required to go from 120mph top speed to 200mph is about 2.78. Comparing that Vette's factory 350hp to a Mustang's stock 205hp, there a factor of 1.70. Multiply that 1.70 by the area advantage of 1.42 and the drag coefficient advantage of 1.34 and you've got a combined factor of 3.26

God i hate Engineers !! they make me feel so stupid I dropped my slide rule about half way through that and just went into brain freeze lol

Originally posted by PKRWUD
Just buy a plane and put the wings on upside down.

ÅChris

LMAO Now thats good ... simple and to the point ! Forget the engineering calculations and just get ya a vehicle with 10 tons of down force and a couple of massive turbofan jet engines with afterburners and a jato rocket pack strapped to the side to get ya goin then just grab your huge brass balls tightly and push the freekin button lolol

[chico]

Using this web site analyzer....my cobra pulls 515 rwhp at 7000 rpm,s. To achieve 200 mph with my gears I would have to pull 7250 rpm,s....assuming I wasn,t airborne at that point P.S my gears re 4.10 ,s

[Dark_5.0]

I know a guy that lives in Dallas that has a LS-1 camaro he was on the quest that you are on.

He dynoed close to 500RWHP and with 2.73 gears he only achieved 190 something MPH.

At those high speeds the drag coeficient plays a huge role in limiting the top speed of your car.

Later.

[NYC1]

I have no real input on how to do it, but out of curiousity, what type of place might this speed test take place?

Did you say a streetable car, or just a car?

Some pro mods can go over 200mph

[jim_howard_pdx]

To go 214 mph in the Pantara, we had to eliminate the air flowing below the car, so as the car moves through the air, vacume is formed beneath the chassis to glue the car to the ground. We built complete pan rails to make the air flow smoothly under the vehicle.

Study funny cars, Nascar and other fast moving objects.

Interestingly, it is the airflow from the windshield on that really effects vehicle handling. The smoother the air falls away from the windshield and the trunk the faster your times.

We converted a US Countach to European specs once for a 15 year old that wanted it built like it was in Europe.

We calculated the horsepower at 414 hp after the conversion.
That is all it took to get that missle to 209 mph. My buddies turbo porsche had 465 hp and quartered in 10.60. In a half mile he was at clipping along at 178 mph. His top speed was 188 mph (mostly due to the 4 speed transaxle.)

Hope you got some cold hard cash, because the cost goes up exponentially to the mph.

[0h n0 5.0]

Originally posted by NYC1
I have no real input on how to do it, but out of curiousity, what type of place might this speed test take place?

i'm guessin he means like a land speed record, dry lake rocket cars
sanctioning boody NHRA, USAC....

North American Land Speed Record

Classifications

The car classes are divided into four general categories: Special Construction, Vintage, Modified and Production. There are general rules for each category and they are related to safety of construction, drivers’ attire, drivers’ qualifications, basic configuration of the vehicle and so on.

The special construction is the pinnacle of the wheel driven straightaway racer’s art. It contains three groups. The Unlimited Streamliners, open wheeled Lakesters, running blown and unblown, gas or fuel engines and Unlimiteds. These are all-out straightaway vehicles with non-stock engine blocks allowed, innovation is unlimited. Modified production bodies are forbidden.

The Streamliner class is for the all-out land speed, wheel driven record car. Cars in this class must have four wheels, but they need not be arranged in a rectangular configuration. The design of the body is restricted only to the extent that at least two wheels must be covered.

The Lakester cars are constructed in such a way that there is no streamlining, fairing or covering of the wheels and tires. Tread width is optional so long as no part of the body or axle fairing is wider than the narrowest inner vertical plane of the tires.

Unlimited class is a special category for the Thrust Powered vehicles. They may be propelled with jet, rocket or any other means dreamed up by humans. There is no limitation regarding wheeled power. There are restrictions against using winged surfaces for controlling the vehicle. Winglets can be installed but must be fixed in one position and not controlled by the driver from the cockpit. Cars in this class also require a minimum of four wheels.

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Bonneville Salt Flats, Utah. The salt flats are located 10 miles East of Wendover, Utah. At one time the course covered over 100,000 acres and the salt depth was over 36 inches. Today the salt flats is closer to 26,000 acres and the salt is three to four inches deep and in some places the mud shows through the salt. The old "International Course" was 13 miles long. Currently we have only seven miles left to race on. The "SAVE THE SALT" campaign has been successful in that Riley Company has been ordered to start a resalting program designed to put .4" of salt back on the race course each year. Eventually we expect to get some distance back and we may once again see the very fast cars breaking records.

Black Rock Desert, Nevada. Located 100 miles North of Reno, Nevada. The nearest town is Gerlach, population about 75 on a Saturday night. The lakebed is a dried alkaline. When dry enough to run on, about September to November, it looks parched, cracked and dusty. When the wind blows, and it really blows hard at times, the visibility drops to near zero. The course can be as long as 19 miles. There is considerable rubble on the surface so defodding is necessary. The Bureau of Land Management requires a bond and cash fund set up for their use while a race team is utilizing the lakebed. The surface acoustics of the dirt appears to have aided the supersonic run by the Thrust SSC by absorbing the sound shock wave rather than reflecting it back to the bottom of the vehicle.


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[drudis]

A 1993 Cobra will require 480rwhp to do 180mph. It takes over 700rwhp to doo 200mph in the same car. You do the math on how much air resistance plays into effect.

Many guys I have run with can do 160mph "fairly" easily, its WHERE you gonna find that stretch of track to do it in! (not on the street).
I personally have done 157mph on 1/2 a lap of Michigan International Speedway (see Mustangworks video clips) several years ago.

With the new motor combo, I should be able to hit 180mph. Working on the aerodynamics (this winter) to keep it on the ground...

[vetteeatr]

So Basicalyl i can have the same 200 top speed with half as many horses if i get a streamlined body?

Jim were those numbers rwhp ro engine?

Thanks

[PKRWUD]

Originally posted by 0h n0 5.0
i'm guessin he means like a land speed record, dry lake rocket cars

My name is on the side of the worlds fastest Motorcycle. We set the record in 1990. I'm sure it's been broken since then, but it was the worlds fastest.

Take care,
ÅChris

[82 GT]

Vetteeatr , no disrespect, but I don't think the average person off the streets has the balls to drive 200mph.
Seriously though, do you think a person straight from the bleachers could climb into John Force's funny car and go 300+ or even a NASCAR stock car and go 200?
If you ever build this car, do forget to dump some serious cash into the brakes as well.
Maybe you could fabricate some kind of ejection seat so you can bail out if the speed gets to be too much
If this is to be a street car, then just where in GOD's world are you going to go that fast........on the way to Wal-Mart??

[vetteeatr]

well i was actually thinking on the salt flats.

I dont think you guys realize a streetable car that goes fast is not that much diffrent im thinking on realibility. Aero dynamics and suspension im sure but as far as motors and transmission blowing ot pieces there are many cars driving everyday wiht more horsepower then i need.

I mean yes it may have 550-650 HP but that is done with alot of motors in our mustangs even and beign kept streetable by forced indcution stock cam and all.(Althoguhi nreality iw oudl probalyl have to cahgne a few htings on cam to make everything beinhg right with gears and RPM's

I was readin gover at turbo mustangs and they are putting out over 600 RWHP on teh stock cam and is fulyl stretable.

THis is on a 302 nonetheless

Also if i decided to go wiht the fiero paltform i woudl be usign a bigger motor and it woudl be that much easier. Which i probayl will end up doing as I dont exspecialyl want a freaking 1000 HP car just so i can do 200 MPH a few times in life.

Im not sayin gim some average beer gutted 42 year old race fan trying ot be jeff gordon. Before i even attempted **** i woudl have one hell fo alot fo safety things and consult prefessionals jsut to see if im gona fly off.

As for 200 MPH on the street probalyl never will happen maybe on a race track who knows but its not as unrealistic as you guys may think i mean considering maybe 30K in a project and be able to basically hang with the 1/4 million dollar supercars is not all that bad.

Is it really that unrealistic?