BigIslandSevens

iTrader: (4)

Where is it documented? I just asked a question dude. Chill the **** out. Didn't mean to hurt your feelings about the stock body.(Sorry i have other real work to do beside sit around and memorize #'s from the internet) Damn, I asked for someone to show me where to look and all you did is bitch! Thanks for the help!

Anybody that has a link to where this is documented i would appreciate it. even you Rynberg if you can do it without being a dick!

And my example is the RB boneville car. They had to put little "chines" /fins if that is the correct name for them. on the next car they took out. ( Partially due to the flip that occured during the white FD test run.) Yes there were otherreasons for the flip. That is why i said partially in the first post , so easy does it rynberg

yzf-r1

iTrader: (1)

LOL

classic Jim Labreck

rynberg

That's the problem with the internet, it doesn't convey subtleties of inflection.... I didn't mean to sound like I was bitching at you. Sorry.

Here's the 93-95 numbers:

Aerodynamic Coefficients of (1993-)1995 Mazda RX-7

Baseline RX-7 RX-7 R2(R1)
Cd, drag coeff. 0.29 0.31
Clf, lift coeff FRONT 0.16 0.10
Clf, lift coeff REAR 0.08 0.08

The 99-wing is adjustable from

Rear wing angle
(degrees)
1
5
10
14.5
Clf
(front lift coefficient)
0.045
0.047
0.051
0.053
Clr
(rear lift coefficient)
0.000
-0.025
-0.058
-0.075

Thanks to Steve and Crispy for the info. You can see the massive improvements Mazda made with the 99 front end and wing.

BigIslandSevens

iTrader: (4)

Thanks Rynberg! I really didn't take it that hard.

And for sure that is the biggest problem with internet conversations, you can't hear the tone in which it is meant.

Thanks for the #'s, That will be helpfull when some of my "younger" customers start arguing the downforce created by the mad tight kits yo!

Thanks again and sorry for my snappy comments as well!!

jimlab

As Rynberg stated, yes they did. Buy yourself a copy of the Yamaguchi 3rd gen. book if you want to see and read about the clay and wind tunnel test models that were produced during the design of the FD.

Not necessarily, although it's not an unreasonable assumption. I've heard that it was a mechanical failure that induced the crash of the Racing Beat FD. At that speed, it doesn't take much to upset the balance of the car.

There isn't any that I know of. My belief is that the car is "safe" up to and including the stock power-limited top speed of about ~160 mph, but I've seen no data stating that Mazda tested at higher speeds than that. Past that point, you're taking your life into your own hands. I've done it once, and I'll probably never do it again.

BigIslandSevens

iTrader: (4)

Thanks Jim,
I saw the #'s for aero and thanks for the book title.

The statement about plenty of you going 160 was in reference toa couple of posts on here about "how fast have you had your FD" or something like that. Some have said 170 some less. And i have done 170 before in a car and a bike, and you are definetly taking your life ito your own hands. I personally love the rush of it. But won't try my FD until I get to a desert or something really long.

I agree that the car is relativly safe as is. And the RB crash as I said was partially due to aero, ( more the after effect of spinning). I also heard the suspension failure rumor i think it was. I believe that i read on their site somewhere that the car also needed the little fins addedd to it for the next year. ( One of the many lessons learned in a 215 mph crash i would think huh? )

RB did the high speed testing for mazda ) to my understanding from their site) When Mazda stopped importing the FD, They stopped getting help/support for their testing. Hence why they don't do much of it anymore. ( Again to my knowledge, as I am stranded out on this damn rock!)

yzf-r1

iTrader: (1)

I'll take the bike over a typical FD at 170 any day much more stable

and this is one place the Supra really shines....top speed king of the jap imports

st0k3d

wasnt that a wind tunnel they had the cwest car in in the video???? with the little sticky things on it?

BicuspiD

Looks like its in a wind tunnel in that pic..
But the significant lap times differences shouldnt be dismissed so easily, the drivers out there are very familiar with the tracks.

Now, taking a car with stock tires over ~140 I'm with you... but I'd bet the C-west car is more stable than stock.. Just my .02 I don't ever drive fast enough to need increased downforce. PLus bodykits don't create downforce when sideways

RX794

I know the Mazdaspeed Bodykits have been tested, they're used on Mazda's competition cars in Japan.

jimlab

It does, doesn't it.

That would make the C-West kit an exception to the rule, however.

The lap times weren't significantly different, which was the point. A couple seconds difference could be attributed to a number of factors.

BicuspiD

2.5ish seconds on a lap isnt significant? IMHO thats huge, especially on an average, and not one fluke run. I Granted heatsoak, tires, etc etc all play a part, but it can't be dismissed when consistently repeated

I think Mugen is one of the others that gets to use a windtunnel.

Agreed though - Exceptions to the rule. I best most bodykits create more drag and lower top speed, or at least unsettle the car

jajiddam

I don't understand why people are just hating on the wing. It's a 20B dammit. I has enough power to take it to such speeds where the wing would actually be functional. The person that put it on probably knew what he was doing. It would only look stupid if it was functional and was just weighing the car down... but not in this case.

t-von

iTrader: (8)

I agree. The stock lower lip of the front bumper doesn't sit low enough for speeds higher than 160. I too took my car to it's top speed limits early last year. The front end seemed to lift slightly at that speed making the car feel a little unstable. If you look in front of the car with the stock bumper, you can clearly see the bottom of the splash pan. Air will hit the splash pan causing the front end to slightly lift at higher speeds. The lower lip of the 99 spec bumper sits lower smoothing out the air flow under the car.

Kevin T. Wyum

I'd strongly question the C West wind tunnel issue. My reasons are two fold. a) a beauty shot parked at a wind tunnel doesn't mean any testing was conducted, there's a big step from parking a car and taking a picture and actually doing real testing, hell it would even be neat to turn the tunnel on and get some neat shots with a smoke trail, but it doesn't mean real testing or development was conducted, as someone else mentioned, Mazda spent what, hundreds of hours in the wind tunnel? b) let's assume they actually had conducted real testing, if they had made that significant investment in wind tunnel time, any positive results from those tests would be plastered all over every snippet of advertising the company puts out.

What should a rational person conclude from this? Perhaps there's some cultural difference that I'm not sensitive to that explains away advertising the positive benefits of a product to sell it. With that caveat aside I'd say they either just did a photoshoot at a windtunnel to lend credibility to the product, just like manufacturers show pictures of OEM cars at a race track, or they did some real testing to get numbers, hoping they'd get good figures to brag about to sell more product, but instead they got back crappy numbers that they're keeping tight lipped about because the kits actually hurt performance.

Okay well there's another little twist, maybe they do adverstise great results in markets none of us are privy to see. Well just some thoughts. : ) And no personally I have no opinion on these kits. I don't even know what the kit looks like.

Kevin T. Wyum

jimlab

You have far too little common sense and far too much faith in the average human being's intelligence, my son...

I think you meant non-functional, but it quite clearly looks bad even if it is functional. You lack good taste as well.

jimlab

Who's dismissing it? I'm saying that it can't be SOLELY attributed to the change in body kit because there are too many other factors involved which could have affected the results.

Obviously they didn't manage the swap immediately, so in the hour(s) between running the car without and running with the kit, temperature and barometric pressure could have changed, track conditions could have changed, the engine was allowed to cool down, etc. Hell, they could have upped the boost for all we know.

As Kevin said, they WANT you to believe that their body kit is solely responsible for the change in lap times to sell you one. Maybe it is, maybe it isn't, but that's what sells the kit, and you've already bought it hook, line, and sinker. Being skeptical is not "hating". It's being realistic about the lengths a company that wants to sell you something will go to in order to close the sale.

rynberg

Amen to Kevin's and Jim's points. I have a feeling that if you took 1/3 of the forum members and stranded them in the desert, you could still sell them sand......

BTW, as someone who has actually been on the track, I SERIOUSLY doubt that the addition of a C-west body kit is solely responsible for a 2.5 second lap time reduction. As Kevin brought up, if the C-west kit actually did anything, we would be seeing Coefficient of Lift and Drag numbers -- but we don't.

InsaneGideon

Maybe I missed something in the meantime...

As "indifferent" (I'm trying to be polite here) as I am about bodykit aesthetics:

Look again at this page chopstix posted a link to earlier:
http://www.c-west.co.jp/labs/fudo_rx7.html

I can't read the Kanji, but there are bar graphs of "DF", "SF", "LF", "LFf", and "LFr" comparing the stock body (looks like pre-'99) aero performance numbers to their full kit.

Then again, they may have just pulled those numbers out of their asses.

jimlab

LFf represents lift in the front (which you'll note is basically unchanged by the C-West nose) and (as one would expect), the big-*** wing provides downforce in the rear (LFr) over what appears to be a wingless configuration. Big surprise.

Interestingly, though, converting m/s to mph, I get...
30 m/s / 0.27778 = 108 kph = ~67 mph
40 m/s / 0.27778 = 144 kph = ~90 mph

Why would you pay for time in a wind tunnel and not test the car at speeds at which the downforce would actually be useful? What happens at 120 mph? 150 mph? 180?? If you did test the car at those speeds, why would you not publish the data?

Well, it looks like the C-West kit is safe for use at speeds up to and including 90 mph...

You never know.

FDNewbie

iTrader: (10)

Yep...very true. I'm one of them lol.

I used to have a stock body R2, and I pushed her to I believe around 150 a few times, and she wasn't that solid, believe it or not. Solid, yes. But did I feel like it wasn't no big thing? Definetly not.

I'm not claiming the C-west kit is the end-all difference here, but simply stated, after my C-west front & rear bumper, c-west front canards, Mazdaspeed skirts, RE diffuser pro, custom undertray, wider tires, and a large GT CF wing, she felt ROCK SOLID at 165. All this was on the stock suspension too...the car wasn't lowered. I felt no jerkiness or instability whatsoever. Sure, the spoiler (among other possible body parts) increased drag to the point where it took quite a while to go from 160-165mph, but I'll trade off drag for downforce anyday.

This isn't the first time I've heard that C-West parts do have some aerodynamic testing behind them. As many (eg. Jimlab) have pointed out, however, if there is rock solid data, we don't have it, for anything above 90mph at that. But MY personal experience has not left me w/ any instability or sudden aerodynamic issues during my speed runs...

Jimlab, I'm not doubting you or the C-west website...but I don't understand how lift could possibly be the same for the stock and the C-west front bumpers. The C-west front bumper sits MUCH lower than the stock front bumper, and a bit lower than the stocker + lip. Also, I'd think that the larger air dams in the C-west bumper would allow more air to flow through the bumper, reducing air resistance, vs. the stock bumper...am I correct in these assertions?

BicuspiD

Touchè

I will contact C-West in Japan and see if they have numbers for anything higher, for grins.