how the hell are you people even talkin' about aerodynamics? holy crap this is bad science.

the reason for the sti wing being more effective (maybe) is notice how SOLID the flow is across the wing. this means that the wing is more efficient. how did they do this? something about the slope of their roof and the rear wind screen coupled with the height of the spoiler and maybe that rood spoiler MIGHT have something to do with it too.

notice how frayed the evo wing flow is... that's not a good thing. this means directly under hte wing you're getting trash flow... that's terrible for efficiency.

the bernouli equation does not account for all the pressure differences across the wing. most of the pressure differential is indeed caused by velocity differences but what causes the differences in velocity is the question. it is a combination of increased distance, accelerations due to direction change and also overall pressure changes due to normal forces which cause a high pressure zone at the leading edge. all this can be summed up as "turning flow" so wings create force by turning flow.

the reason the scoob has better downfoce capabilities probably lies in the fact that it has lots of downforce adders... mitsu gave us some fins on the *** and some razors on the back and called it a day. if you look under a an sti you'll see that there's a pretty nice diffuser in the back, there's some pretty nice stuff in the front too.

 

Does anyone know whether the JDM or JDM replica rear bumpers improve the rear lift? I have an MR with the 0 lift kit (LOL) and can tell you the car has a lot of air flowing underneath it (and lift) at speeds over 110 mph. I would love to add a front splitter and a rear diffuser et al in the rear. Thoughts?

 

This is very interesting..

 

I thought aerodynamics was what this was all about? The Bernoulli principle was just a basis for discussion....not a formula to account for all variables. It still comes down to the fact that the wings are airfoils and create low pressure on the curved side. This allows the higher pressure on top of the wing (in the case of our cars) to push down into the area of lower pressure. This probably isnt enough to overcome the lack of a rear diffuser as you so stated.

What is your definition of "turning flow" I see it as being just another way of describing the Bernoulli principle. You have to take this into account. Afterall, we are discussing the wing here.

There is some good reading on this site on boundary layers.
http://www.av8n.com/how/htm/spins.ht...boundary-layer
And even better explanation of airflow over wings
http://www.av8n.com/how/htm/airfoils.html

I think you are very right triny in saying the evo needs a rear diffuser and that the airflow over the suby wing is intact, more so than the evo's. This is why the Evo in the wind tunnel tests are so terrible.

Another thing that may help would be an adjustable wing. Something that you could change the angle of attack on. It would be interesting to put a rear diffuser on the car, coupled with the VG's and redo that wind tunnel test. I've seen a few places that rent access to wind tunnels for around $300 an hour.

 

great thread.

 

very cool, doesnt look like the roof wing on the STI does anything

 

interesting

 

isnt there a video that shows the evo moving and than they put some colored gas to see how the wind goes thru the vehicle or something like that?

 

Actually it does exactly what it was designed to do. It helps direct the airflow coming off the roof directly at the leading edge of the rear wing for optimum effectiveness of the airflow and wing profile in creating downforce.

 

Ree,



Great post.. by the way, this is one of the topics less covered on this forum. I truly find an irony to see those graphics and those findings.

Let me explain, Mitsubishi launched the 3000 GT VR4 back in 1990, and as many of you know this car came equipped with a Sytem Active Aero. Mitsubishi engineers gave this car a special edge as far is the ultimate performance handling.

This clearly indicates that back then(16-18 years ago if you include reserach and development) Mitsubishi Engineers mastered the wind tunnel technique by aplying the theory and testing to the real world(Mitsubishi 3000 GT VR4)

Not only that but Mitsubishi also lay the smack down by putting other gadgets like AWS(All Wheel steering), ECS (Electronic Control Suspension), Electronic exhaust control(Sport /touring). Mitsubishi showed the world that they could be the "top dog" when they wanted it.

With that said, I found absolutely absurd that a modern team of 21st century engineers actually delivered a product (Evo) with such unlawful and embarrasing CD numbers and down force numbers.

Sorry guys, I am not buying that. Either this car was significantly compromised for short acceleration and improved cooling(multiple openings throughout the entire front of the car) or perhaps the Mitsubishi engineers actually marketed this car disregarding fuel compsumtion and aerodynamic. Pick one.

There got to be a reasonable explaination, I mean, this car has hollow cams, aluminium fenders and hood,aluminium control arms, magnesium valve covers, Brembo brakes, recaro seats, momo, forged rims,teflon cables,aluminium roof,ACD,YAWC, ... you name it. Do you guys think Mitsubishi couldn't accomplish a better aerodynamic standards? Cmon guys!!

Carlos

 

Completely agree. It doesn't make sense that the Evo is not that aerodynamic just becuase Mitsu was lazy. Obviously they were not.

 

Ummmm...only if the greater path for the air to travel was above the wing. If the cross section of the wing has the greater path of travel on the BOTTOM, then the lift is inverted...i.e. downforce.

Missed it by only that much.

 

Yeah but the Evo 7 came with a variable(manually) pitch rear spoiler. The issues still persist:


1) too many openings(hood, front grill and front bumper)
2) and boxy cuts lines all over the body (fenders, hood)

It is a mistery..

Carlos

 

Rally heritage....nuff said.

If you want aerodynamics, buy a Ferrari...or an airplane.

 

It's also called marketing and business sense.

Within Mitu's business model they still have to uphold profit and protect against loss. While R&D is utilized for the important things for the Evo, extreme aerodynamics was not one of them. I can think of several reasons why not:

1. To remain somewhat competitive in rally, aero is not as big of a consideration b/c a lot gets changed by the privateer teams.

2. The consumers won't pay for a ton of real aerodynamic work put into a 30K japanese sedan. As it stands, MOST people don't "get" this car, let alone sinking more money into a car that only an enthusiast could appreciate and love.