FDNewbie

iTrader: (10)

If he's talking about *THE* FD that did 215 on saltflats...that thing didn't stand a chance. If you watch the video...it started turning sideways...then the rest was history.

You can't tell tho what caused him to spin like that...if it was lift on the front end, a strong crosswind, a sudden bump or jerk in the driving...unless someone talked to the guy and asked him?!

Oh and I know I'm definetly no where near an *expert*, but someone tell me, don't saltflats offer very little traction, as opposed to say, concrete? That was one of my main concerns

theorie

iTrader: (31)

ditto

DamonB

That is true. There is not as much mechanical grip from the salt.

FDNewbie

iTrader: (10)

????????


And so he decided to hit 215 w/ shaky grip at best?? Doesn't that strike *ANYONE* as even remotely odd??

I was hoping I was missing something or my assumption was wrong, but if I was tryin to hit anythin over 140mph, im pullin out the slicks and makin sure i got perfect asphalt road, cuz in my mind, traction is VERY important...

rynberg

Uhh....because he was trying to set a speed record at the Bonneville Salt Flats? Ever heard of them?

FDNewbie

iTrader: (10)

I might have...name rings a bell

But Rynberg, the question I'm asking is, if you were there, and you were trying to set a record, would you do it on salt flats? I don't care much if the event is held there...to me it's a no brainer. I just wouldn't it do it there. I'd want perfect conditions, perfect weather, etc as perfect as it gets...

Enough can go wrong w/ normal conditions at such speeds...to try that under poor conditions (horrible traction) i think is a poor use of judgement at best

Kento

Then perhaps you might convince someone to pave a perfectly flat stretch of tarmac at least 5 miles long and preferably a half-mile wide, where people could legally make controlled and measured speed record attempts. That's the reason that people use the salt flats, because when it dries in the right conditions, you get a totally flat surface for a long distance.

And let's not dredge up the "this road near my house is flat, and I've done 195 mph in FD" statements, please. If you've ever been over 200 mph, you'll know how critical it is to have an absolutely smooth surface. Even the smallest rises and dips in the pavement over half a mile can literally become motocross jumps at that speed, and obviously, getting any part of your car airborne will be catastrophic.

Sgtblue

iTrader: (16)

For what it's worth, Police Packages, now almost solely FORD Crown Vics, are sold with factory calibrated and certified speedometers. While statutes may vary slightly from state to state, actually speedometer clocks, or "pacing" (terms also vary) are easier to obtain convictions with than radar in many cases. The reason is, pacing tends to give you the speed of the target over an extended distance where as a radar or laser reading is the target's speed at the instant the antenna or gun was activated. It follows then that if a Cop gets a pace reading w/his speedometer AND a radar reading, it only solidifies the case.

BTW, you guys are scaring me. I can understand doing 150mph plus on a track in a properly prepared/equipped car, but doing these speeds on a public road/highway? Ok, so you have Z rated tires and a car w/ some effective areo bits. Most of you still have no rollbars and stock belts w/ no helmet, together with any number of hazards on the road and beside it.
At the risk of telling "war stories", I've seen what rolling at 100+ can do to a car and it's occupants. It ain't perty guys. Please be careful.
Besides, I like going slow enough so other motorists can see the big-*** grin on my face from being able to own and drive an FD.

rynberg

Geez, man. Type in Bonneville Salt Flats in google or something.....

Howard Coleman

iTrader: (6)

hi speed freaks, i just discovered this thread and it is interesting. i have gotten alot of laughs over the last few years over the barndoor "aero-kits" for the fd. what a joke. mazda spent tons of money developing as small a frontal area (19.26 sq ft) and drag coefficient (.31 for the non r-1/2) because they wanted to make the car as fast as possible. there are 2 primary factors to solve for the energy needed to drive a car a certain speed. they are frontal area and drag coefficient. for example let's solve for the fd at 175 mph... rear wheel hp =s drag coefficient (.31) times frontal area (19.26 sq ft) times 175 mph CUBED/ (divided by 146,600). that'd be 218 rear wheel hp. to get to rear wheel hp Carol Smith (Tune to Win) uses 11% loss for driveline/transmission and 60 hp (remember we are going 175 mph) to drive the wheels. answer: 305 at the crank. pretty easy to go 175 w a few mods. but it gets harder from there because you have to CUBE THE SPEED. for instance 200 mph is 426 crank hp. a 14% increase in speed and a 40% increased in required power. notice that drag coefficient and frontal area have a linear effect. cut the drag or frontal area 10% and go 10% faster. in addition to top speed remember for you acceleration guys that any hp in excess of what is needed to drive the car thru the air at a given speed, say 85 mph, is what you have to accelerate with... so aero is an important factor in drag racing. btw, the r1 package, i believe, changes the drag from .31 to .34. if that's the case it will take another 41 crank hp to reach 200 mph. that's the cost of downforce.
howard coleman

Flybye

I want everyone to notice something about the FD that flipped at 215mph....



Ok, those easily look like 185 or 195 tires. Ok fine, the vette was designed to go past 200mph. Was that on a paved surface wiht REAL rubber underneath or wearing rubber tires rolling through a surface which probably has the same consistancy as a tiled floor with billions and billions of little ball bearings everywhere. I'm making this analogy because that is what I can only assume the salt flats are like. If I'm wrong, please correct me.

I'm not a high speed expert, nor am I a physicist. I'm only going by real world observations and a little bit of commonsense. So....a car at THAT speed......using tires that small....on a surface no where near having the traction quality of a paved surface.....is it of no surprise that a small gust of wind could possibly send it spiraling to its death? And yes, the rear end of the FD DID start coming out, causing a slide, and the rest you know.

What if the same test were done with a C5 which Jimbo KNOWS it was designed to go past 200mph. Same conditions, same bycicle tires, same small possible gust of wind. Could it possibly do the same to the C5 as it did to the FD?

jimlab

So? Do you know what the 300+ mph streamliners run on?



Here are the specs of the streamliner above...
Length: 24'
Width: 38"
Height: 41"
Frontal area: 7.4 sq. ft.
Coefficient of drag: 0.119
Power: Twin 450+ CID blown alcohol Donovan big blocks
Trans: Twin liberty 5-speed, air actuated (4 wheel drive)
Front track width: 26"
Rear track width: 15"
Tires: Mickey Thompson high speed (24.5" x 7" x 16")
Wheels: 4.5" x 16" steel
Top speed: 438.815 mph

Now, you were saying something about the width of the tires?

Yes. Where have you been? The Lingenfelter 427 TT C5 ran 226 mph on stock rubber with stock aerodynamics.

http://www.motortrend.com/features/p...112_0304_fast/

You're wrong, it's like slightly wet, compact sand. Ever seen the tires of a car that's driven on the salt flats?



Who said anything about a gust of wind? At that speed, all that has to happen is for your aerodynamics to break down and generate a little too much lift. It's pure speculation anyway, unless you were in the car, and even then you might not know what happened.

Probably not. Not at 215 mph, anyway.

Laz74

I don't understand why some of you are so hung up on the Racing Beat FD accident. The car was specifically prepped for a top speed run, and I'm sure Racing Beat did some homework before building a car designed to sustain 200+ mph speeds.

In addition, I may be incorrect, but from what I have heard in the past, a suspension problem caused the car to become unstable and lose control. As you can see in the video, the car only flips over after the rear end slides out. Since Mazda never tested the FD sideways in a wind tunnel, it didn't really stand a chance to stay on the ground when it was going sideways at 215 mph.

Also, skinny tires would be beneficial on a "slippery" surface like the salt flats, because it bites into the surface. Putting wide tires on the car would cause it to float on the surface, minimizing traction, much like skinnier tires give you more traction in snow than wider tires.

Flybye

Yeah but that's my point. The FDs rear end didn't lift first. It started coming sideways. Hey, if you can explain how lift will first make the rear swing out BEFORE lifting, then please do

RotorJoe

Then how does the R1/R2 have a lower drag coefficient then the stock base models?

FDNewbie

iTrader: (10)

LOL..you know what gets me Rynberg? Sometimes it's as if you more experienced members practically expect us novices to know what the game's all about... a game you've been in for *years* longer than I have, mind you.

Maybe I've had my head buried underground. Maybe I've been asleep too long. Either way, I'm obviously new to it. So give a lil. Patience my man. Can't learn it all in one day, now can I??

Kento...id like to think that there are a cpl multi-mile long stretches somewhere in this greatly vast country of ours...how long are airplane runways on that note?

And before you jump on "perfectly flat," saltflats are the opposite extreme... they're no where NEAR a perfect surface as Laz74 pointed out w/ his snow analogy *shudder*

I think Flybye and I are on the same page w/ the traction part... whether or not thin tires will give you better traction under those conditions, I'm saying you shouldn't be dealing w/ those conditions TO BEGIN W/ lol. Snow/saltflats vs. tarmac??

I guess my biggest conflict is trying to understand what diff. aerodynamics will make when all the drag, lift, and downforce you're trying to work w/ is ultimatley to be applied to a surface w/ which your traction is compromised to begin w/???

Point being, I'm dyin to find the top speed of my FD, but you won't find me tryin that on any saltflats...ill take my chances w/ asphalt anyday thank you very much

jimlab

I think it's been pointed out that it was likely mechanical failure that caused the accident. My point was that all it takes is exceeding the ability of the car's aerodynamics to create downforce and the car becomes (literally) a wing...

Flybye

They don't.
The base have a cd of .29. The R1/2 has a .31

jimlab

It doesn't. The Cd of the R1/R2 is 0.31 and the Cd of the base model is 0.29...

Edit: ****, you beat me to it.

FDNewbie

iTrader: (10)

LOL..that's hilarious. Terrifying, yet hilarious.

But that's exactly my point of conflict... what's the point of downforce to begin w/ when you're working w/ a very compromised surface (saltflats), as compared to asphalt? Your traction practically sux...

Granted, more downforce will give you better traction *for your circumstances*, yet it'll be far less than the traction you can get on a decent surface...you know?

jimlab

There are reasons why people go to Muroc and Bonneville to run top speed... nothing (and no one) to run into, miles of straight, flat surface, and controlled conditions. If the salt's no good, they won't let you run. If the wind is bad, they won't let you run. There is medical help waiting should you need it. Do I need to go on?

Kento

Negative, narrow tires are used because 1.) they offer less frontal area for less drag, and 2.) it's a lot easier to control tire carcass heat with a smaller cross section tire. If they actually "bit" into the surface like you describe, they would create way too much rolling resistance.

FDNewbie

iTrader: (10)

Jimlab...I'm sure of that. No doubts there. But again, my point is, given a choice between saltflats and asphalt, I'll take asphalt anyday.

Now if we simply don't have such paved areas that would work for these top speed runs, that doesn't mean I'll settle for what I think is nearly suicidal...I just won't find out

Kento

Oh, I'm sure there are, but are they perfectly flat across their complete length? Would you want to find out if they're flat enough at top speed in your car?

The longer runways at major airports are about 1.5-2 miles if I'm not mistaken; I'm sure you could just call them to shut down so that you could do some speed runs...

Oh really? Have you ever driven/ridden anything on the salt flats? I have, and while the surface isn't billiard-table smooth, it's a lot smoother than any speed runs I've done on pavement, hands down. I've done speed runs on countless motorcycles on pavement that looks billiard-table smooth, until you get up to 190+ mph (and yes, the roads were legally shut down for this). And remember that motorcycles lack the aerodynamic downforce of cars.

Well, you basically said it in the middle of your statement: if your aerodynamics are right, you don't have to worry about the traction quotient with regards to stability. That's part of the allure of the salt flats for these people-- balancing the downforce/traction so that they can extract the most speed from their aerodynamics and horsepower.

ronarndt

Anyway- To get back to the original question. 170+ with stock body with R-1 wing. Also, 4.3 rear and non-stock motor.

Now if you guys want to really test your pucker power, try going flat out on a in-shape 17 hh thoroughbred race horse. No air bag, no seat belt, bad brakes, nominal steering.
Ron A.