EVO Aerodynamics Review
Evolved Member
Joined: Sep 2006
Posts: 761
Likes: 0
From: East Hampton Ct.
Love the look of the car! I saw it last year at the last Mid Ohio event as I was leaving. I caught a glimpse of it out of the corner of my eye and was like "what the hell is THAT crazy thing!" I spent about 10 minutes looking all over and around it, but no one was around to talk with. I really like some of the ideas you have going on there, especiall the DTM style side skirts. That's what they remind me of anyway 
And for some reason the rear diffuser reminds me of a jet fighter plane or maybe a Can Am car or something like that.
A couple questions - how did you come up with the rear diffuser design vs something more standard such as this:
Is your front splitter flat on the bottom or does it have diffuser tunnels along the lines of these:
Here are a couple ideas/observations on the splitter based solely on what I've read (as in - no real world practical testing I've done). The depth of the splitter under the overhang of the front bumper does not gain much downforce, at least compared to that which is gained by the part that sticks out past the front bumper when looking down from above. You may consider having the air dam come down vertically fromt the leading edge of the bumper rather than a few inches under the bumper. Also - any extra bit it can extend forward without scraping or breaking the rules will add some downforce, up to a point. Four to six inches is usually a good place to start.
If allowed by rules - running a 3-d undertray portion to the front splitter will help make much more downforce than just a flat panel. I would guess in the neighborhood of 50% more downforce - maybe more. You get the high pressure on top of the lip sticking out in front of the car, as well as the negative pressure suction under the car from the venturis. . .
Take this all as conjecture - my opinion and understanding and theory. . .
And for some reason the rear diffuser reminds me of a jet fighter plane or maybe a Can Am car or something like that. A couple questions - how did you come up with the rear diffuser design vs something more standard such as this:
Is your front splitter flat on the bottom or does it have diffuser tunnels along the lines of these:
Here are a couple ideas/observations on the splitter based solely on what I've read (as in - no real world practical testing I've done). The depth of the splitter under the overhang of the front bumper does not gain much downforce, at least compared to that which is gained by the part that sticks out past the front bumper when looking down from above. You may consider having the air dam come down vertically fromt the leading edge of the bumper rather than a few inches under the bumper. Also - any extra bit it can extend forward without scraping or breaking the rules will add some downforce, up to a point. Four to six inches is usually a good place to start.
If allowed by rules - running a 3-d undertray portion to the front splitter will help make much more downforce than just a flat panel. I would guess in the neighborhood of 50% more downforce - maybe more. You get the high pressure on top of the lip sticking out in front of the car, as well as the negative pressure suction under the car from the venturis. . .
Take this all as conjecture - my opinion and understanding and theory. . .
I met Charlie North when I was running the BMW driver schools at Lime Rock Park. I made him our chief tech and received a bunch of flack because "he didn't drive a BMW". I said when you can find me a better qualified engineer to make judgment calls on the safety of our students BMW cars, I'll fire him. Till then he was and still is one of the brightest most ingenious race car mechanics I have met. His company's name is Function First Motorsports. He is one of the original Mitsubishi fans with his collection of Dodge Colts, Starion's and VR4's. He started as a aircraft mechanic, raced mortorcycles at Daytona, then began a career working on sports cars and building race cars.
Sorry we missed you at Mid Ohio. Planning to go back for a regional and the championship event. The front splitter becomes a continues flat bottom to the rear diffusers. No separate tunnels underneath, all flat. The side skirts form the boundary. The front splitter and side skirts are around 2.5" above pavement. Stainless steel heat shields cover the area below the exhaust. Charlie understands were he wants to effect pressure. He asked me before we started "how wild looking could I make the back of your car"? We researched Chinese composite panels but the cost were unrealistic. The local Alumilite material was easily available, cheap, strong and light enough to work.
I met Charlie North when I was running the BMW driver schools at Lime Rock Park. I made him our chief tech and received a bunch of flack because "he didn't drive a BMW". I said when you can find me a better qualified engineer to make judgment calls on the safety of our students BMW cars, I'll fire him. Till then he was and still is one of the brightest most ingenious race car mechanics I have met. His company's name is Function First Motorsports. He is one of the original Mitsubishi fans with his collection of Dodge Colts, Starion's and VR4's. He started as a aircraft mechanic, raced mortorcycles at Daytona, then began a career working on sports cars and building race cars.
I met Charlie North when I was running the BMW driver schools at Lime Rock Park. I made him our chief tech and received a bunch of flack because "he didn't drive a BMW". I said when you can find me a better qualified engineer to make judgment calls on the safety of our students BMW cars, I'll fire him. Till then he was and still is one of the brightest most ingenious race car mechanics I have met. His company's name is Function First Motorsports. He is one of the original Mitsubishi fans with his collection of Dodge Colts, Starion's and VR4's. He started as a aircraft mechanic, raced mortorcycles at Daytona, then began a career working on sports cars and building race cars.
I wish we lived closer so i can see it. Btw, i didnt know you have a flat bottom. How do you work around it? Does it all come off when youre done racing so you can transport it? Or do you have an enclosed trailer? What do you do when you have to work on it? And how do you jack it up? I remember that you posted some pics of your new aero in one of your threads, but i dont remember reading anything about the details. If youre up for it, post up a thread with all those details. This way its easier for other people to find it. There is a lot of good info out there, but when people post stuff in different threads its almost impossible to find it because you have to scan through endless amounts of posts and threads. If you recall, we recently added an APR splitter to my Evo along with my friends GTC-200 wing. Ive been meaning to post a thread of my new aero. Its really a simple first step for me, and at the same time i can illustrate what i go through every time i race. It takes me a solid 45min to just install my splitter (that includes jacking up the car, removing front wheels, installing brake ducting hoses, splitter, air dam, reinstall wheels, and lower car).
Although, my splitter is mounted to the chassis. And its only on the car when im racing. Either way, i cant imagine how long it takes you to get your side skirts on, flat bottom, and everything else on and off. I would love to know your process...what stays on all the time, what you install when youre racing, what you have to remove depending on what you need to work on...so forth.
Ed hows come you gotta take your splitter off each time? If it's a loading/unloading issue i think it'd be more worthwhile to get 2x12's in such a manner that the splitter doesn't touch the ramps?
And there is no way i can get in and out of any driveway.
Gotcha. Right now i'm using the APR splitter but I installed Dzus fittings along the front so it takes about 3 minutes to drop it including the subframe bolts and front "adjusters" if you can tall them that. I'm thinking of doing Dzus for the trunk/spoiler setup too once I get to that.
Evolved Member
Joined: Sep 2006
Posts: 761
Likes: 0
From: East Hampton Ct.
Dave, your Evo definitely has one of the wildest looking aero. I wish we lived closer so i can see it. Btw, i didnt know you have a flat bottom. How do you work around it? Does it all come off when youre done racing so you can transport it? Or do you have an enclosed trailer? What do you do when you have to work on it? And how do you jack it up? I remember that you posted some pics of your new aero in one of your threads, but i dont remember reading anything about the details. If youre up for it, post up a thread with all those details. This way its easier for other people to find it. There is a lot of good info out there, but when people post stuff in different threads its almost impossible to find it because you have to scan through endless amounts of posts and threads.
If you recall, we recently added an APR splitter to my Evo along with my friends GTC-200 wing. Ive been meaning to post a thread of my new aero. Its really a simple first step for me, and at the same time i can illustrate what i go through every time i race. It takes me a solid 45min to just install my splitter (that includes jacking up the car, removing front wheels, installing brake ducting hoses, splitter, air dam, reinstall wheels, and lower car). Although, my splitter is mounted to the chassis. And its only on the car when im racing. Either way, i cant imagine how long it takes you to get your side skirts on, flat bottom, and everything else on and off. I would love to know your process...what stays on all the time, what you install when youre racing, what you have to remove depending on what you need to work on...so forth.
I wish we lived closer so i can see it. Btw, i didnt know you have a flat bottom. How do you work around it? Does it all come off when youre done racing so you can transport it? Or do you have an enclosed trailer? What do you do when you have to work on it? And how do you jack it up? I remember that you posted some pics of your new aero in one of your threads, but i dont remember reading anything about the details. If youre up for it, post up a thread with all those details. This way its easier for other people to find it. There is a lot of good info out there, but when people post stuff in different threads its almost impossible to find it because you have to scan through endless amounts of posts and threads. If you recall, we recently added an APR splitter to my Evo along with my friends GTC-200 wing. Ive been meaning to post a thread of my new aero. Its really a simple first step for me, and at the same time i can illustrate what i go through every time i race. It takes me a solid 45min to just install my splitter (that includes jacking up the car, removing front wheels, installing brake ducting hoses, splitter, air dam, reinstall wheels, and lower car).
Although, my splitter is mounted to the chassis. And its only on the car when im racing. Either way, i cant imagine how long it takes you to get your side skirts on, flat bottom, and everything else on and off. I would love to know your process...what stays on all the time, what you install when youre racing, what you have to remove depending on what you need to work on...so forth.The APR 200 wing needs the extensions to move it up into the air flow. After the 1st weekend using the extensions, the wings leading edge is showing wear from track dust coming over the roof. The extensions are around $100 and they'll make a big difference.
I made Lexan side vent windows to close in passed the A pillars. The Seibon doors I bought are really poor. Its going to take some work to build out the rear windows flush with the body. At Mid Ohio this summer a wild thunder storm collapsed our tent onto my Evo's roof! Dents all over the roof and pillar.... The quarter panels are banged out to make room for the 17x9.5 18mm RPF1's Yea it needs body work and a paint job bad. It looks like a hodge podge of parts now but it really fast! When I see a nice clean silver Evolution 8 an the highway I think what the hell did I do! Better to have one for green flag race condition were you can go REALLY fast!
Can't wait to get a proper wing.
Dave - Just to be clear, I wasn't trying to say your aero setup is wrong or needs improvement, simply different than what I have learned/been taught. Where did the inspiration for the design of the rear diffuser come from? It looks like the diffuser begins forward of the centerline of the rear tires?
For your side skirts - did you have to cut or clearance the front doors or fenderwells at all?
I can relate to the loading/unloading pain of having the splitter. I take it off and put it back on every time the car goes on or off the trailer. This is my 3rd revision, but I finally got the mounting setup very solid yet comes off in 2 minutes with just 4 bolts you can reach by sticking your hand up under the front of the splitter. . .
For your side skirts - did you have to cut or clearance the front doors or fenderwells at all?
I can relate to the loading/unloading pain of having the splitter. I take it off and put it back on every time the car goes on or off the trailer. This is my 3rd revision, but I finally got the mounting setup very solid yet comes off in 2 minutes with just 4 bolts you can reach by sticking your hand up under the front of the splitter. . .
If a design could be made where the splitter would fold up or slide back for front ground clearance it would solve much of this install -> remove -> install again BS! I know I would buy one, if I can't do that I'll have to make one myself someday. 
The original DHP prototype design (never mounted on an EVO) was exactly what you are looking for. It was hinged at the back and held by cables attached to the frame in the front. It hung a couple inches below the front bumper and had a vertical air dam kinda like the latest design.
When you loaded it on a trailer or drove into a steep parking lot the front would hinge upward, then fall back down to the proper ride height as set by the support cables. . .
EVOlutionary
When you loaded it on a trailer or drove into a steep parking lot the front would hinge upward, then fall back down to the proper ride height as set by the support cables. . .
EVOlutionary
Dave, your Evo definitely has one of the wildest looking aero. I wish we lived closer so i can see it. Btw, i didnt know you have a flat bottom. How do you work around it? Does it all come off when youre done racing so you can transport it? Or do you have an enclosed trailer? What do you do when you have to work on it? And how do you jack it up? I remember that you posted some pics of your new aero in one of your threads, but i dont remember reading anything about the details. If youre up for it, post up a thread with all those details. This way its easier for other people to find it. There is a lot of good info out there, but when people post stuff in different threads its almost impossible to find it because you have to scan through endless amounts of posts and threads.
If you recall, we recently added an APR splitter to my Evo along with my friends GTC-200 wing. Ive been meaning to post a thread of my new aero. Its really a simple first step for me, and at the same time i can illustrate what i go through every time i race. It takes me a solid 45min to just install my splitter (that includes jacking up the car, removing front wheels, installing brake ducting hoses, splitter, air dam, reinstall wheels, and lower car). Although, my splitter is mounted to the chassis. And its only on the car when im racing. Either way, i cant imagine how long it takes you to get your side skirts on, flat bottom, and everything else on and off. I would love to know your process...what stays on all the time, what you install when youre racing, what you have to remove depending on what you need to work on...so forth.
I wish we lived closer so i can see it. Btw, i didnt know you have a flat bottom. How do you work around it? Does it all come off when youre done racing so you can transport it? Or do you have an enclosed trailer? What do you do when you have to work on it? And how do you jack it up? I remember that you posted some pics of your new aero in one of your threads, but i dont remember reading anything about the details. If youre up for it, post up a thread with all those details. This way its easier for other people to find it. There is a lot of good info out there, but when people post stuff in different threads its almost impossible to find it because you have to scan through endless amounts of posts and threads. If you recall, we recently added an APR splitter to my Evo along with my friends GTC-200 wing. Ive been meaning to post a thread of my new aero. Its really a simple first step for me, and at the same time i can illustrate what i go through every time i race. It takes me a solid 45min to just install my splitter (that includes jacking up the car, removing front wheels, installing brake ducting hoses, splitter, air dam, reinstall wheels, and lower car).
Although, my splitter is mounted to the chassis. And its only on the car when im racing. Either way, i cant imagine how long it takes you to get your side skirts on, flat bottom, and everything else on and off. I would love to know your process...what stays on all the time, what you install when youre racing, what you have to remove depending on what you need to work on...so forth.
Evolving Member
Joined: Oct 2008
Posts: 102
Likes: 0
From: Bloomington, MN
How important do you think it is that the tunnels be exactly where DHP put them? Do you think they would have the same affect if they were in a slightly different spot? The reason I wonder, is I was considering making my own splitter and replicating the channels. Either with Alumalite (may be hard to form) or aluminum.
Also, do you think the center section extending further than the tunnels have an affect and what would it be?
Just trying to get the best ideas for making mine.
Also, do you think the center section extending further than the tunnels have an affect and what would it be?
Just trying to get the best ideas for making mine.
How important do you think it is that the tunnels be exactly where DHP put them? Do you think they would have the same affect if they were in a slightly different spot? The reason I wonder, is I was considering making my own splitter and replicating the channels. Either with Alumalite (may be hard to form) or aluminum.
Also, do you think the center section extending further than the tunnels have an affect and what would it be?
Just trying to get the best ideas for making mine.
Also, do you think the center section extending further than the tunnels have an affect and what would it be?
Just trying to get the best ideas for making mine.
As for the center section, my understanding is quite simple. You extend the center section a little more to help prevent and minimize air that can flow into your engine bay from underneath the car. Beyond that, it also acts as a shield by blocking some of the debris that can kick up and damage your oil pan and other parts.