can anyone decode this for me?

 

http://www.iluvmyrx7.com/2ndgen/pics...es/image33.htm
i cant get it to post a real pic it is just doing a white box with x in it. here is the link.

 

what do you mean decode it? like tell you what it means?
It means the FC has one of the best aerodynamic flow of ANY mid 80's cars

they are awesome. and umm.. that's about all i know

the hood is a low pressure area, and the rear hatch area acts like a natural wing/spoiler

-Mar (KUS)

 

It's actually a pressure profile.
It shows which way air will flow if a hole was drilled at that spot.

 

this thing pops up all the time.. man.. that pic is so old.. is it from the design team?

-Markus

 

Ya I would like someone to explain what the arrows pointing up are? Basically, tell me what parts of the cars there is lift and what has downforce from the chart. Also if anyone has any other cars they got charts on we can compare and contrast simularities in body style. Also this chart dosent have a spoiler on the car, does it do much if anything at all on our cars?

 

My edits are too slow for you guys.

It's actually a pressure profile.
It shows which way air will flow if a hole was drilled at that spot.

 

So does that mean that the air captured my the front air dam travels in then up along the inside of the hood then back under the car?

 

What it means - - if you hit 215 MPH - here is what happens:

High Speed Run - 5MB vid

 

lol i've seen that vid.. pretty scary

with mods and no fuel cut / (not stock Ecu) what can the FD hit? as far as top speed wise

-Markus

 

i cant download videos here? is this the rb fd on the saltflats?

 

LOL, that's my crummy scan from way back - I can tell from the lousy cropping job, hehehe. I got it from a Rotary Rocket magazine article profiling the new 86 RX-7. I believe it is a Mazda file picture, but I'm not positive. I would really like to know what airspeed that picture represents.

Vector Quantities 101: The arrows are pressure points. Arrows pointing toward the car are positive pressure, while arrows pointing away from the car are negative pressure. The length of the arrow shaft shows how much pressure.

My favorite part: Note how the shape of a car forms a natural "spoiler" effect acting on the rear deck.

 

I am guessing the up arrows mean low pressure while the down arrows mean high pressure, relative to atmospheric.

Yep look at the natural spoiler effect of the bare FC fuselage . . oops I mean body. But look at all that negative pressure (lift) coming off the hood. I think that would cause understeer at high speeds . . well at least that is better than oversteer at 100 knots . . oops I mean MPH. I wonder if a flatter hood would make less lift up front.

 

ok so i have a post about pop up hoods so with this chart its basicly saying that air would not escape from the engine bay yet enter it (like a coul induction hood)
https://www.rx7club.com/forum/showth...hreadid=184028

 

also so basicly this chart proves the turboII hood is pretty much useless fresh air headlight covers or pretty useless and removing your ftp lenses is also pretty useless then huh. so a coul hood a front mount intercooler and cold air ducts in the nose below or on the stripping would be the best choice for an rx-7

 

Up to about Mach 0.4, the pressures are going to be pretty much the same, relative to each other (which is what the picture represents, relative differences in pressure). Aside from some slight changes due to movement of the laminar/turbulent transition point, that is, which won't be much even up to 215 mph (flipper speed).

And as the post after yours clarifies, the pressures are increments above or below ambient pressure, not really *positive* or *negative* pressure. I know you already know this stuff; this is just to clarify.

 

Not so! The TII hood has a scoop that alters the shape of the NA hood quite a bit, and in such a way that air is redirected to the IC when it would have just blown on by had the scoop not been there. So the TII hood is definitely not without function. The rest of your comments about headlights and ftp openings -- that's probably right.

 

Drill a hole at that spot? My TII hood scoop is a big hole. According to this pressure chart, air should be exiting the scoop, not sucking air into the intercooler.

On the other hand, maybe I'll get out the Makita (or better yet a sharp punch and a hammer) and put holes all over the car. Dude, I'll have freaking Indy Car downforce!

 

I also like that natural rocket propulsion effect back by the tail lights. Man, you drill enough holes in the back of your FC, then add some little wings on the doors, you could fly! Hell, then all you need is one of those Frank Germano Tesla Tubine things and, well, ****, you could probably turn yer FC into a freaking TIME MACHINE!

 

Hehehe, yeah, there is a natural downforce on the empennage as if there were a horizontal stabilizer with a negative angle of incidence.

Yes, there is lift on the nose, but at least there is a lot of force on the chin. The Bonneville salt flats 10AE RX-7 had a simple air dam added to the front to keep the nose down, and that worked just fine up to 191 mph.

BTW, 100 kts = about 115 mph.

Changing the rake of the hood will also change the aerodynamics. My guess would be that a "pop up" hood would create a lot of drag as the air separates from the trailing edge of the hood. Whether or not the air from the engine bay escapes would depend on whether or not the airflow through the engine bay overcomes the pressure at the cowl.

Do you have two friends? Have one of them drive along next to you on the freeway, while the other one sits in the passenger seat of the other car and takes a picture of your hood with infrared film. That should determine where the heat is going. Just be safe when you do it.
http://rx7.voodoobox.net/infofaq/hotmazda/hot_mazda.htm

Pretty much. However, if there is a hole facing the airstream, air will enter (some exceptons, but I won't go into that). It may not be high-pressure air, but it is air no less. Also, an engine will create its own vacuum to pull in air at the intake. You would need an incredibly strong aerodynamic vacuum to starve-out an engine with good compression.

I have personally tested the TII hood up to 80 mph, and I can assure you that air still goes into the scoop at this speed. One of these days I will also measure the pressure.

 

One aerodynamic improvement that seems so obvious to me and I have never seen executed on a 2nd gen is

side strakes for the hood...

If one just made vertical strakes up to the base of the windshield following the fender/hood gap is it would act like a spillway on a wing and keep air from "rolling" off the body and concentrating the high pressure area on the body at the base of the windshield.

Some nice simple CF strakes... Maybe I will be the 1st

 

Could use guys explain why there in pressure comming off the front of the nose, I would think that would be hard since there would be air hitting firectly in the spot.

 

The Turbo II hood scoops would definately change all the aerodynamic charistics of the hood. The downdoce that happens right before the windshield would be moved farthe down the hood with the scoop.

 

If you notice, those are all basically vectors that are all perpindicular to the body at various points. They point in for poitive pressure on the body, basically, the force that the air produces on that point has been made into a vector showing its weight perpindicular. In the areas such as the tail where they are point out this is slight negative pressure where the air will not really be pushing but pulling slightly. doeas this make any sense to you guys? The arror are large at the beginnning because the force the air is large, then they grow smaller because the air start to move along the body rather than impacting it. then just below the wind shield its not impacting at all, in fact it almost has to dip down, but it doesnt so it pulls slightly.

CJG

 

my head hurts