BMan

I remember reading that the Porsche 928 was exclusivly designed in a wind tunnel and had the lowest CD ever. Then they turned it around and made it backwards because no body would buy it.

KnifeEdge_2K1

you cant really calculate it on paper, most of the time it's done experimentally since in real life applications there are just too many variables to take into account

this aint ur high school physics class man lol

yes drag coefficient is not the only factor which affects drag itself as you've stated the reference point usually the front cross section is used and also speed but since the speed value wont differ from car to car this is only useful in applications concerning a single object the cross section and Cd is what matters most

KnifeEdge_2K1

are you serious ? .36 to .35 is a 3 percent drop
by lowering the Cd of a car by just a few hundredths you can increase topspeed without changing horsepower by nearly 20mph

1QWKEVO

iTrader: (3)

yah drag plays a big role in the highspeed game, but with normal daily driving doesn't matter much... only real world area it would benifit anyone is gas mileage..... either way i'd still like to know what mine is since I can find out what any other vehicles is... Oddly the evo's isn't publicly noted, maybe cause its not as low as mitsu would have liked? who knows

KnifeEdge_2K1

meh, guess we just have to accept it
a few aero mods should smoothen out the flow a bit but the front mount intercooler will always increase teh Cd

first thing i'd do is get rid of the factory bumper, the one on the Sparco/A'Pexi evo looks really nice and it is less obstructive (is that even a word) then the stock one, a rear diffuser as many of you have said already would help and side skirts would too

but this is really only neccesary in a road/track evo, if you plan on actually doing some rough driving aka your pretend rallies, then the difference is minimal since you'll need the extra ground clearence and top speed will rarely be reached in that type of race/competition

1QWKEVO

iTrader: (3)

I wonder wy mitsu took the road of trying to generate more downforce with canards and lips and this and that on the evo instead of reducing lift which would not only increase downforce but also increase top speed and highspeed acceleration... I guess its becasue its easier to push down then pull down huh.. oh well no big deal

Outlaw

Would the Cwest/Veilside aero kit help with this?

KnifeEdge_2K1

what the hell are you talking about reducing lift is the same as increasing downforce, it's net lift/downforce that matters

Ludikraut

iTrader: (17)

Here's my best guess: mitsu probably did this to keep the multiple personalities of the Evo alive - read: on-road, off-road. If they had released a lowered, road-racing version, it would have probably cost them some sales and contradicted the whole WRC inspired theme of the car. I'm sure quite a few folks (myself included) appreciate the fact that the car can hustle across gravel just as well as tarmac and we would have been put off by a "street only" version.

BTW - thanks for the press kit. I've been looking for something from mitsu confirming the effects of the redesigned front bumper. It looked like a lot of thought had been put into it. Hehe, nice to see that my guess was correct.

Also, to contribute to the topic at hand ... I have absolutely no problems believing that the regular Evo 8 has a cd of .36. I mean, just LOOK at it. It sits relatively high off the ground, has a fairly blunt nose, a large wing, and a rear bumper that doubles as a parachute We're talking sedan here, not 2-door sports coupes like the 350Z or Vette. ...and in the end it really doesn't matter, since our little flying bricks still pound the competition ... on-road AND off-road.

l8r)

nabit

best post in whole thread...back to drinkin now fo me..

mayhem

iTrader: (9)

To be more specific it's the Force of Drag that is related to the drag coefficient. But either way, right on!
Little formula for you guys:
(Force of Drag in Lbs) = (Cd * FA * V^2)/400
Cd = coefficient
FA = frontal area (ft^2)
V = velocity (mph)

ccs

Sorry for waiting so long to comment on earlier posts about vortex generators...have been swamped at work....but just wanted to clarify.... vortex generators are effective both with and without the wing.

In simple terms...vortex generators move the point of flow separation toward the back of the car. (Flow separation is generally identified by a region of reverse flow)

Moving the point of flow separation generates higher surface pressures, which results in lower drag. (There are several types of drag, but for now we'll lump them all together). Therefore, with the vortex generators and without the wing, the EVO's Cd decreases.

With the wing there is an added benefit. The displaced flow separation point and the higher surface pressures developed by the vortex generators results in a higher flow velocity at the wing, and thus a lower lift.

Quick

the STEEP rear window

It's the one thing on the Evo VIII that bothers me.
makes it a brick!
I'm suprised it has only been mentioned once in this thread
I guess nobody really payed attention to it or really compared it to other sedans out there..



Looking at the side view, the height from the base of the chassis to where the vortex generator would be, is much greater than
the height from the base to the front of the roof (where it meets the windshield).

It's obvious that the Evo VIII's max height is at this point.

Why would mitsubishi make the rear window steep?
my guess is that all the room for the rear diff, undersized fuel tank , etc.
probably offset the headroom thats required in the passenger compartment, and they maximized trunk space as much as possible by terminating the rear window earlier.

lots of drag

ccs

Found some information from Mitsu about EVO vortex generators, drag, etc. A bit technical and a few rough translations, but generally good. PM me if you need help with the technical stuff.

http://www.mitsubishi-motors.com/cor...004/16E_03.pdf

juyanith

iTrader: (7)

Thank You! That information made wading through the previous mess on this thread completely worthwhile. I'm not an aerodynamic engineer of any sort but I found this quote from the conclusion most helpful:

Application of the VGs of the optimum shape determined
through the abovementioned analyses to the
Mitsubishi LANCER EVOLUTION showed a 0.006
reduction in both the drag coefficient and lift coefficient.

I may actually buy one of those little "vortex generators" now (assuming the marketed VGs are the "delta-winged shaped" ones and not "bump shaped"). Thanks again.