Originally posted by Kento Also, I wonder if the FD driver that Jim speaks of sensed that his car was unstable just before it flipped... 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 |
Originally posted by CCarlisi 150mph. I stopped accelerating due to the self-preservation instinct not a lack of power. |
Originally posted by FDNewbie someone tell me, don't saltflats offer very little traction, as opposed to say, concrete? |
Originally posted by DamonB That is true. There is not as much mechanical grip from the salt. :wtf1: 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... |
Originally posted by FDNewbie ???????? :wtf1: 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... |
Originally posted by rynberg Uhh....because he was trying to set a speed record at the Bonneville Salt Flats? Ever heard of them? 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 |
Originally posted by FDNewbie ???????? :wtf1: 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... 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. |
Originally posted by doncojones I could be wrong here but I do not believe that law enforcement vehicle speedometer readings are admissable as evidence in a court of law--only speed gun readings are. 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-ass grin on my face from being able to own and drive an FD. ;) |
Originally posted by FDNewbie 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... |
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 |
I want everyone to notice something about the FD that flipped at 215mph....
https://www.rx7club.com/attachment.p...postid=2591603 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? |
Originally posted by Flybye Ok, those easily look like 185 or 195 tires. https://www.rx7club.com/attachment.p...postid=2591751 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? :) Ok fine, the vette was designed to go past 200mph. Was that on a paved surface with REAL rubber underneath http://www.motortrend.com/features/p...112_0304_fast/ 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. http://www.roadsters.com/russ.jpg is it of no surprise that a small gust of wind could possibly send it spiraling to its death? 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? |
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. |
Originally posted by jimlab .....Who said anything about a gust of wind? Originally posted by FDNewbie .....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?!..... Originally posted by jimlab ..... At that speed, all that has to happen is for your aerodynamics to break down and generate a little too much lift. ..... |
Originally posted by Quickfini An FD is faster without the stock rear wing. The rear wing adds more drag than actual downforce. |
Originally posted by rynberg Geez, man. Type in Bonneville Salt Flats in google or something..... 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 |
Originally posted by 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 :) |
Originally posted by x605p747R1 Then how does the R1/R2 have a lower drag coefficient then the stock base models? The base have a cd of .29. The R1/2 has a .31 |
Originally posted by x605p747R1 Then how does the R1/R2 have a lower drag coefficient then the stock base models? Edit: Shit, you beat me to it. :) |
Originally posted by 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... :) 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? |
Originally posted by FDNewbie 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 |
Originally posted by Laz74 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. |
Originally posted by 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? :) 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 :) |
Originally posted by FDNewbie 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? 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... :) 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/??? |
top speed
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. |
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