Ground effects project

[brandon3212]

So recently a guy showed up in my local car group that works with carbon fiber for a living and has started making car parts on the side. I have wanted a front splitter for the longest time but didn't want to fork out the cash for OTS options that IMO doesn't look that good and also doesn't do anything. I had ran across the pictures of COBB's Speed 3 race car with an epic front splitter that looked amazing and is functional (within reason). I contacted COBB and asked if they had any drawings or info on this splitter but was told that the car had since been sold and the splitter removed. They didn't have any drawings or additional pics either.




After talking to some people that know more than me about Aerodynamics pointed out that this is a good starting point but there is still efficiency to be had. I can add winglets and canards later to possibly improve the design if I can determine the best place for them. I made a mock up with corrugated plastic board to get an idea of what it looked like and for measurements.

Splitter is 3" long and the air dam is 3" tall




I'm not yet sure if I'm going to continue the carbon fiber all the way under the engine bay or not, it will depend on how much extra its going to cost, it might end up being an aluminum tray.

I'm meeting with my carbon fiber guy this week so I'll post and update when everything is 100% decided.

[radbrad]

Very interesting. Are you looking into making a smooth under tray for the full length of the car and a diffuser for the rear?

[brandon3212]

Originally Posted by radbrad Very interesting. Are you looking into making a smooth under tray for the full length of the car and a diffuser for the rear?

The car is fairly smooth underneath as t is, I will have to see where it can be improved.

I have some plans for the rear diffuser, that will come later.

[radbrad]

I mean like a legit under-tray. ImageUploadedByTapatalk1437349001.716325.jpg

[brandon3212]

Like I said, I'll have to see where it can be enclosed. I'm still taking this 1 step at a time currently.

[anavrinIV]

Just an FYI but a real functional splitter needs to connect to the chassis, not just the bumper. The purpose of a splitter is to divide the air such that the air passing underneath is faster moving (lower pressure) along a smooth surface while the air above stagnates and creates a high pressure region resulting in downforce. If you attache only to the bumper you'll just bend the plastic and create nothing more than a visual splitter.

But I'm sure you know that already.

[Thepedigree13]

Is this a dedicated track car?

Just curious, if so then good luck I hope it helps with your times/speed.

If not, it looks ugly and I wouldn't do it to my speed3.

[brandon3212]

Originally Posted by anavrinIV Just an FYI but a real functional splitter needs to connect to the chassis, not just the bumper. The purpose of a splitter is to divide the air such that the air passing underneath is faster moving (lower pressure) along a smooth surface while the air above stagnates and creates a high pressure region resulting in downforce. If you attache only to the bumper you'll just bend the plastic and create nothing more than a visual splitter. But I'm sure you know that already.

Yes, your absolutely right

This probably wont attach the the bumper in any way, it's mounting to the crash bar and most likely other solid points as well.

Originally Posted by Thepedigree13 Is this a dedicated track car? Just curious, if so then good luck I hope it helps with your times/speed. If not, it looks ugly and I wouldn't do it to my speed3.

The car is tracked at least once every 2 weeks at my local road course. It will be interesting to see if this has enough effect to change the handling characteristics at all. It is still driven daily.

I understand that the look isn't for everyone as it's not subtle AT ALL, I personally love the "race car" look though.

[Thepedigree13]

Good shit. Subbed to see the progress and end result.

Pretty cool having the hook up on carbon fiber.

[brandon3212]

Originally Posted by Thepedigree13 Good shit. Subbed to see the progress and end result. Pretty cool having the hook up on carbon fiber.

My carbon guy is awesome, this would not be possible to do paying normal shop prices. He quoted me around $500 for the whole thing, while that sounds expensive the lip from DG motorsports is $450, doesn't do anything and is way smaller.

[brandon3212]

I've been reading up on rear diffusers and believe I have come up with a reasonable design. In order for the diffuser to be effective it needs to slope upwards towards the top of the bumper. Unfortunately there is no room for a upward slope with the current bumper design without modification. I decided that I will just cut the lower section of the bumper cover out to make room for the desired curve.

While this looks sexy as hell it probably isn't very effective from what I have read.


From what I understand, this is how the air is supposed to exit the rear of the car.


I took a picture of the back of the car and threw it into MS paint for some sketching. This is by no means perfect, but at least I can get a bit of a slope from the rear control arms to the edge of the bumper. Sorry for the light colour, it's kind if hard to see

[razerer]

you might be able to salvage a diffuser from another car.. that way you might not have to do a complete fab. easiest stuff that seem to work for mazdas are wrx stuff and evos. but evo stuff maybe wider and needs quite a bit of cutting, which at that point might as well fab the whole thing. Regardless cool plan.. Subbed!!

[anavrinIV]

I've had the same thought for a diffuser in the past, it would definitely require cutting up the rear bumper cover. It would also be best to close over the exhaust tunnel and rear suspension bits as much as possible to get a more contiguous path for air to flow smoothly

[Easter Bunny]

Removing the muffler would crate tons of room for a diffuser. Keep in mind for all of this to work you will need rocker extensions to seal off the underside of the car.

[Nliiitend1]

@naoandlater;

Do you still have that diffuser laying around?? Or do you have plans for it?

[naoandlater]

Originally Posted by Nliiitend1 @naoandlater; Do you still have that diffuser laying around?? Or do you have plans for it?

I do have the rear diffuser. Plan is to sell it locally, since it's so big.





But, my original plan was to install the diffuser without adding additional trays on the bottom. Here is the pic of the rear diffuser on a mz3.

[monkey.bones.007]

Originally Posted by naoandlater I do have the rear diffuser. Plan is to sell it locally, since it's so big. But, my original plan was to install the diffuser without adding additional trays on the bottom. Here is the pic of the rear diffuser on a mz3.

Locally eh, I'm in Illinois for 2 more weeks.... Just saying.

tapatalk, it sucks

[brandon3212]

Originally Posted by razerer you might be able to salvage a diffuser from another car.. that way you might not have to do a complete fab. easiest stuff that seem to work for mazdas are wrx stuff and evos. but evo stuff maybe wider and needs quite a bit of cutting, which at that point might as well fab the whole thing. Regardless cool plan.. Subbed!!

I had thought about this, but buying anything half decent is big $ and would probably have to come out of the state's. This should cost me under $200 to build, even if I have to get the strakes laser cut.

Originally Posted by Easter Bunny Removing the muffler would crate tons of room for a diffuser. Keep in mind for all of this to work you will need rocker extensions to seal off the underside of the car.

My resonator is pretty tiny, I hope to make this work with the exhaust where it is. I have one of the original resonators from CPE, it sits right up in the exhaust tunnel.

I have some plans to seal up the bottom of the car, I was actually thinking about some flexible skirts to hug the road. Kind of like they used to do in formula 1.

Originally Posted by naoandlater I do have the rear diffuser. Plan is to sell it locally, since it's so big. But, my original plan was to install the diffuser without adding additional trays on the bottom. Here is the pic of the rear diffuser on a mz3.

That not really what I'm after, thanks though.0

[brandon3212]

This is what I'll probably do to seal the bottom of the car. I could probably use that garden edging crap all the kids are making front lips out of, it should be durable and flexible. The car still needs to be capable of driving around town, so anything 100% rigid is out of the question since it would get smashed.



This picture isn't that relevant, but it kind of gives you an idea of how the skirts direct the air toward the rear diffuser.


I would like to mount it inboard and angle it toward the center of the car so its kind of out of sight, I do want to keep the build tasteful if I can.

[brandon3212]

I dropped the front splitter template off with my carbon guy. I was told approx 2-1/2 weeks before it's finished.

Apparently the motor in his Genesis decided to tank, so hopefully this doesn't affect the timeline.

[Lewis7789]

I found this universal diffuser for a pretty good price on eBay. Might be an option.

Universal Rear Diffuser Kit Under Body Spoiler Increased Down Force Reduce Drag | eBay

[Easter Bunny]

Other than it having a profile that would not provide any downforce.......

[Lewis7789]

It's my understanding that a rear diffuser doesn't add any additional downforce anyway. It just straightens the air flow from under the car. But I'm no aerodynamics engineer.

[Easter Bunny]

Your understanding is not correct. Fashioned correctly a diffuser can be more effective than a wing.

[brandon3212]

I'm still going to build my own. I don't trust Ebay junk even if it did work. The strakes on that are tiny anyway, mine will be huge and scrape everywhere.

Foam core for the front splitter has been completed, carbon is supposed to be getting laid sometime this week. My carbon guy is very slow, but at least I didn't give him any money yet haha

When I actually have some half ass pictures I'll post up some progress. I'm still moving forward with all aspects of this project, this isn't dead.

[Lewis7789]

Originally Posted by Easter Bunny Your understanding is not correct. Fashioned correctly a diffuser can be more effective than a wing.

Then I stand corrected. It was my understanding for this application, without a fully flat underbody, the read diffuser would simply help reduce drag and not create downforce. But I guess the byproduct of reducing drag is downforce. But a rear diffuser on a proper flat bottom race car certainly makes sense.

I only started researching aerodynamics for my similar application on my MS6 yesterday so I'm learning as I go.

[Crarrs]

There is so much wrong in the post above that I'm just going to hope your research pans out with some actual facts. While drag and downforce are certainly related, one is not totally dependent on the other like you're stating.

[akurma]

did anything ever come of this ?

[brandon3212]

Things got delayed since my carbon fiber guy was taking forever to do anything so I decided to build the front splitter out of wood for now. I'm hopefully starting this weekend.

[brandon3212]

Carbon fiber isn't happening, but aluminum is. Front splitter is all measured up, just need to draw it in CAD and send the stuff to the laser cutter.

Rear diffuser plywood mockup


Both tow hooks need to go and the exhaust needs to be changed from the rear subframe back




After I cut out a whole bunch of wood to check fitment I discovered the strakes are way too tall (not surprised).




The diffuser is up as high as it can go and is touching the spare tire well.


Thinking of making a nice dual tip exhaust that will route above the diffuser and exit out the side of the back bumper. This is just a simply drawing of a plate that pipes could exit through and not melt the bumper.

[brandon3212]

Front end aero is 70% complete give or take. Still needs an air dam and a pile of bracing.

Exhause is done

Rear diffuser material is on order

Side extensions and bottom pan need to be designed still.






Splitter braces are attached to brackets welded into the crashbar. Canards have aluminum backing plates behind the bumper.





IMO it looks sick as fuck all mounted up and snow covered




Much more work to be done...

[Vansquish]

Yep, definitely got dem dere ankle slicers.

[brandon3212]

I like how they cap off the sides of the splitter in this kit. I think I'll copy it.

http://www.tf-works.com/rocket-bunny...-diffuser-kit/

[jtday]

Originally Posted by brandon3212 I like how they cap off the sides of the splitter in this kit. I think I'll copy it. Rocket Bunny 180SX & S13 Rear diffuser kit - TF Works - Real Racing Parts

I like what you've done thus far. Interested to see if track times yield any solid determinations!

The rocket bunny kit was always the eagle-amongst-pigeons kit in my 240 days..

[MSP611]

this is a cool idea and if it functions well then im all for it... im not a huge fan looks wise of ur front canards but thts just my opinion. I wish people made carbon shit like this for us... What happened to ur carbon fiber guy, he just bail out?

[brandon3212]

Originally Posted by MSP611 this is a cool idea and if it functions well then im all for it... im not a huge fan looks wise of ur front canards but thts just my opinion. I wish people made carbon shit like this for us... What happened to ur carbon fiber guy, he just bail out?

You really need to be into the whole "time attack" look to like it.

Carbon guy was flaky, nice guy but was all talk and took FOREVER to get anything done. I'm glad it's aluminum anyway, just in 1 week alone this splitter has taken a massive beating and bent both mounts where the supports attach.

I'm going to weld some 1/4" plates around the mounting holes.

I'll gladly post up my CAD files so others can use and modify my designs. It wouldn't be hard at all for someone to clean up the canards and make them smaller.

[MSP611]

ahhh well thts shitty... and id have to start from scratch since i do own an ms6 not a 3 just thought this was a cool thread...

[brandon3212]

Some drawings of 2 different styles of side plates/strakes and rough drawing of a multi part bottom pan. If I make it out of multiple parts it will be much nicer to form to the bottom of the car. I can overlap and move panels around as needed. The skinny part is just going to be a trim piece or something incase I need to clean up the area around the bumper above the diffuser pan.

I'm just going to have a big variety pack of parts cut. The laser cutter is across the street and most of my parts are free through work.





EDIT: Oh, if anyone has some ideas for side skirt extensions that might fit in with everything else post up. I really want to do something but currently have no clue what.

[Code Monkey]

Use conveyor belt material for side skirts -- flexible enough and strong enough to go up and down as you hit curbing.

[brandon3212]

Air dam is done, should be getting it welded up next week sometime


Beginning of the bottom pan of the diffuser. Will be getting trimmed up to better match the curves of the bumper




Still trying to figure out what to do with the massive black hole that is the rear subframe and control arms