I need this for and idea I have. Now, don't hate on a brotha for his ideas. You guys will like this one. I (French voice)garontee(/French voice) it. Please post that pic.
Thanks in advance.
Charles

 

all you had to do was search for wind tunnel my friend..... you should know how to search by now.....

here ya go... i searched for "wind tunnel"

enjoy

 

 

I consider myself fairly smart about engineering & physics type stuff, but that picture doesn't make any damn sense to me. I'm assuming those are force vectors, distributed load or something.

 

yeah, someone please explain that sucker.. it seems to me that the car has an INCREDIBLY high lift characteristic

 

Yeah, the aerodynamics of our car do suck.
To simplify the explanation of the airflow diagram above try this:
The first area (from the bumper to 2/3 back on the hood)
is a "bow wave" and yes the air there is lower pressure
than ambient.
The area from the windshield to the back window is definitely creating lift. Bernoullis law explains that displaced air is accelerating over a larger distance than
if it could go straight back to the area behind the car.
This causes the air molecules to be farther apart, hence low pressure or "lift".
Incidentally you will observe that a spoiler in the traditional area is of little value compared to one on the roof that extended above the low pressure. Watch out or the RICERS will really screw up the car.
That diagram telles me if I want to vent hot air from underhood I will need the hole in the hood fairly far forward to work.

 

The CD of the RX7 is better than most cars out there now. It is in the .30's. The convertible being the worst with a drag coefficient of .38 with the top down.
Compare that with a new Mustang GT at .36(old were even higher). For a 1986-91 car, the RX7 was awesome.

Interesting flow profile. Would love to see an actually video of the RX7(without/with a T2 hood) in a wind tunnel with air/smoke/tape and everything.

Bummer its an FD:
http://www.autospeed.com/A_1080/page1.html

 

Ah, yes. It all makes sense now.
Well not all of it...
I've gone and confused myself further. So, the headlight cover vent is in the highest vacuum area on the car at high speeds. In that concern is a headlight cover vent pointless? Counter productive? Also, the position of the TII hood scoop is near a vacuum, but I guess the air flow would be different with that hood?

I do see how cowl induction would be advantageous in this case...

 

2nd gens had a drag coefficient of .31, and the sport model with stock sport aero parts has a .29 cD, same as the FD, only other car i know of with a .29 is the eclipses, everything else is .30 and up, except like racers and ****, but thats different

 

Yes, it does seem like the headlight door intake would be of litle value

 

Corvettes also have a cod of .29

 

This subject has been frustrating me to no end because i kept thinking there has to be some reason why you would put a headlight intake on in the first place. So, i did a quick search on the internet and found a website that put into words what i was thinking.

http://www.gmecca.com/byorc/dtipsaerodynamics.html

They make it seem that the intake isn't pointless or counter productive because over the headlight covers it is a spot of massive amounts of slow moving air resides. The trick is that this air is looking for some way to spread itself out again to an equilibrium, that's why you have those massive arrows indicating high pressure over the hood.

Now, when you add this NACA duct as they call it, you are giving the bottom layer of air molecules (the ones closest to your paint job) another way to reach equilibrium and they will accelerate and flow through the duct.

Check out the site for yourselves if you still don't believe me, the page also goes over scoops, spoilers and wings.

Phu5ion

 

Only slightly related to this topic, but a while ago when I saw that drawing I took it and colored it in, etc. What do you guys think of the finished product?

 

**** that coloring is tight. Is that Soul's car? hehe.

Rishie

 

I am having trouble seeing how the leading edge of the car can be a low presure zone. It of all places should be a high downward presure area. Thanks for the pic.
Charles

 

people need to understand that a high CD isnt necesarily a bad thing, a good thing is when its a low CD but with many lbs of downforce. for example, the lexus ls430 has a cd of .26, do u think its more stable at 180 mph than an fd?

 

Looks like the air intake is near the area of highest positive pressure. Has any one done any flow tests/dyni test to prove that an after market air filter/stock box removal/cone acutally does deliver 5, 10, 20 more HP?

 

just thought i would do this for kicks.. re make the old mazda one.... maybe someone could clean this up better and we can use this

 

I like it!

 

bcty, remember to put the ends of the arrows in so people know high and low pressure zones

All cars (excepting VW busses and such) will have a similar variation of that chart. Why did Mitubishi add a big lipped vent on the forward section of the Evos hood? Because that low pressure area is going to follow the vertical frontal area of any car, I imagine.

Don't despair, there is a lot of airflow over the hood to draw from regardless of wheter it is high or low pressure relative to other areas of the car- but, I am still drawing air in the high pressure frontal area and venting out the low pressure hood front for my TII projects horizontal mount IC...

 

uh.. I think the old one looks a lot better

 

No they don't. The general shape of the pressure profile will be the same for practically every car. You always get high pressure at the very front and at the cowl; you always get low pressure over most of the bonnet and over the windscreen and roof. The exact shape of the car (plus any aerodynamic add-ons) will determine how high or low theses pressures get, but the general shape will always be the same. the FC has a respectable Cd for its age, especially considering the technology used today to get figures that aren’t much lower.

 

So is it possible to make a 'hatch' spoiler that will be functional without being 'ricey'. And if so, why hasn't it been done? Hmmmmm.... anyone have any ideas?