I want a different look on the rear and like the looks of a few things jdm IX, deffusers ect, but I also want something that serves a purpose. I have seen a ton of deffusers and even some people make them using the stock bumper and look pretty good. So what works and what doesnt?

 

Aerodynamics is such a huge topic to discuss here. Making real improvements on Mitsubishi's design will require tons of reading books, research, searching, looking at examples, and etc. A good start would be to review some of the wind tunnel work Mitsu did here http://www.mitsubishi-motors.com/cor...004/16E_03.pdf

That said, there are a few basic proven things you can do to improve aero performance. First, you can reduce the low pressure behind the rear window and on the trunk. Adding the OEM vortex generator will make gains there.

Second, you can reduce the high pressure build up in the rear bumper cover. Covering the area between the rear cradle and rear valnce with a smooth, flat material will help keep air out of there.

Third, you can increase the effectiveness of the rear wing by adding the OEM wickerbill, aka "Gurney Flap". Making real gains beyond these will required real education, research and testing.

Best of luck!
Ethan

 

How about one of these??

 

Vishnu makes a nice rear diffuser.

 

I'm working on a FUNCTIONAL rear diffuser that would fit the USDM 8/9 rear bumper. The design will include a large center diffuser pan flanked by symetrical banks of three vertical winglets which will in turn be flanked by two more diffuser pans that will cover the axle-back and smooth out a large section of the underbody in the rear of the car. The design will also eliminate the dreaded parachute effect that our bumpers create.
-Alex

 

do a search for diffuser and you'll find several custom examples, including my own

 

At the very least you can rest assured knowing everything OEM has seen a wind tunnel. It only takes a slight flaw in an euro part to go from good to bad, and you can't know until you know...you know? However, obvious things like covering the gap for air to collect under the rear bumper probably can't hurt...

 

OH...MY...****ING...GOD...

I don't know why they stopped there...I'm sure they could have fashioned an adapter to mount an inverted Cessna airframe to the trunk...then maybe wire in a custom JDM S-AYC controller to some servos to control the rudder...that would be sweet...

 

I understand that it takes real education, research and testing and thats why Im not willing to just go make a deffuser as many have done. I want something that proven to work and not just slapped on there cause it "should" work. The car already has a apr wing and I like the looks of a lot of different things, but this is the exact setup I would like to do.
voltex on a jdm IX rear, just not sure if it will be better then stock. Also what is a wickerbill, aka "Gurney Flap"

 

a gurney flap is a lip on the trailing edge of the rear wing. it increases down-force by increasing the deflection angle. this also creates some drag.

edit: the drag is "miniscule" according to wikipedia

 

the most important part is to seal up that bumper....

 

Just FYI, the pic of the white EVO in the garage has the Voltex rear under wing. It actually acts as a wing element as it has air flow both over and under it. Diffusers usually just have airflow on 1 side.

EVOlutionary

 

Thanks for the sarcasm! That actually is my daily driver car. We were test fitting the wing that is now on my race car. I realize not everyone is willing to go big to get the downforce they desire. Some will be satisfied with lackluster performance so they don't have to make their car look like a "race car".

EVOlutionary

 

This is what I'm considering:


I agree with what others have said. Eliminating the hole created underneath the rear bumper will probably get you 98% of the way there.

 

but just sealing up the rear wont get me the look i would like, and thats at least 15% of it for me