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Old 03-23-2016, 04:34 AM   #1
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Default Autocross Class Unknown - An exercise in not caring

In attempting to keep with my catch phrase "The best things come out of Iowa," I have begun building my Miata without any regard for SCCA classing. If you don't already believe the best things come out of Iowa, then just take a look at Ron VerMulm's E mod Camaro.

Starting from the beginning.

It's December 2014, I had a big fat insurance check from somebody totaling my daily driver a month earlier. I find myself contemplating the purchase of a Miata almost two times a day. At that point, I did what any general car enthusiast does and I hit the forums for information and the local craigslist to see what I could dig up. After some research, I had decided that I wanted something with the Torsen and a 1.8, preferably on the NB platform.

After a couple weeks I found this "gem" on craigslist. It was a price I could easily afford, and it checked the box on every single one of my requirements.


Throughout the summer, I campaigned the car locally in E Street with a set of BFG Rivals and some Carbotech brake pads (1521 front and ax6 rear). I was always on the pointy end of the class, even with old and worn out suspension. I even won a local series quite handily (though, the classing is a bit...easy to cheat... more on that later). Things were great, I was getting used to driving the car, but I just kept on wanting more.

At the end of the season, I decided it was time to step up a class or five... into D Prepared. At the time, I saw this as the set of rules that would best allow me to achieve my goal of a modest power - super lightweight car. So, I put the car up on jack stands and started tearing it down, getting rid of everything that isn't necessary for race car things.



A few hours into the tear down process, I had some not so pleasant findings...



After finding all this rust (on both sides of the car), I decided it was a good idea to check the strength of said rails. This is the result.



As you can imagine, I was completely devastated. I spent weeks trying to come up with a plan to fix the rust. Should I try to cut it out and weld some new metal in? Oh wait, I have zero welding skills. Maybe I can afford to have somebody else fix it. But then on second thought, that's probably going cost more than the car is worth.

After discussing some possibilities with a friend that lives in Arkansas, I had come to the conclusion that it was most economical to just start over with a new (to me) chassis. Fortunately for me, he had a friend who had just tested the strength of a concrete barrier with the driver side fender of his NA6 and was looking to offload it for a very low price. After pouring over the literally dozens of pictures he took of nearly every square inch of the car, I decided to pull the trigger on it. We met half way in Warsaw, MO (which is kind of funny since he is German born). After viewing what is quite easily the cleanest Miata I have ever seen in my lifetime (aside from the light body damage), I handed my cash over, and it was time to start the 5 hour trek back to Iowa.

Here it is the day after I brought it home (with my TRM C1s on it).



At this point, I had done enough reading to know that I had just procured the lightest Miata and already owned the Miata that has a powertrain that would support my modest goals. It was like a match made in Miata heaven, but one thing was missing. Racecar parts. In order to remedy this, I called Emilio at 949 up and discussed my short and long term build goals. A couple weeks later, I placed my order, and all this showed up at my doorstep. Ignore the second swaybar, that belongs to a friend that added his order on top of mine to save on shipping.



So far, a pretty standard "I'm building an autocross car" thread.

This next part requires a little bit of background information about myself. I work as a technology specialist in a middle school. Part of my required duties is teaching 7th and 8th grade level engineering/technology classes. We spent a month working with Autodesk's Fusion 360 3D modeling software. In order for me to effectively teach that software, I first had to learn how to use it myself. What better way to do that than to design race car parts? I started with something fairly simple: a front splitter. After that was done, I decided to tackle rear wing design.

This opened up a whole can of worms for me. What air foil should I use? How wide should this thing be? How long should my cord length be? And lastly, the question that would determine the answers to the previous questions... Do I care about breaking any rules about aero? If you can see where this is going, the answer to that last question is positively a "NO".

After arriving at this conclusion, I started doing research. Most specifically on how to make lots of down force at relatively low speeds. After several failed ideas, and some brainstorming with an engineering buddy of mine, a light bulb came on. That lightbulb was Formula SAE. They know how to make downforce at low speeds.

After reading some dissertations written by some graduate students, I finally settled on an airfoil profile that I wanted to try for iteration #1. After choosing the profile, I did some math. Theoretically, with the cord lengths I chose, the wing should make ~70 pounds of downforce at 27 miles an hour. ~280 pounds at 54 MPH. ~1,120 pounds at 108 MPH. All at maximum angle of attack before it starts to stall.

The second best part about it is that it looks completely ridiculous when attached to the car.



After getting everything the way I wanted it, I sent the profile to a CNC foam cutting company. A few weeks later, I had some foam cores that will soon be fiberglassed.



Yes, it's massive... and it looks smaller than at that angle...than it does at this angle:



Next on the to do list was to install all my parts from 949 and the torsen out of my 99.





All suspension parts installed! Let's not forget to put the giant MAZDA stickers on the sides.



Next on the agenda was to get wheels and tires. Now, before I divulge any more, I'm going to note that I know this is not the optimal setup for the tire/wheel size.

I ordered a set of Konig Dial-In 15x9s (which will become my street wheel after this year) and Hoosier R25Bs in 23x9.5R15. This is another point where I decided that I was going to run what I want and not care about what class I'm going to get thrown into.

Here, have some more pics:




Last edited by ChasB; 03-27-2016 at 07:28 PM.
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Old 03-23-2016, 08:54 AM   #2
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Assuming that you are also going to do some sort of forced induction since you are on this forum. Not sure why you want to build an autocross car with no concern for classing. You are probably going to end up in XP or some mod class if you get too wild with it. That aero already looks like it takes you out of SSM, but you may be able to trim it to class size. There are some of the fastest SSM cars in the nation on this forum if you're interested.
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Old 03-23-2016, 09:32 AM   #3
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If you haven't found these already, check out Oregon State's thesis archive. Their aero thesis' are top notch.
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Old 03-23-2016, 10:59 AM   #4
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Originally Posted by 90civichhb View Post
Assuming that you are also going to do some sort of forced induction since you are on this forum. Not sure why you want to build an autocross car with no concern for classing. You are probably going to end up in XP or some mod class if you get too wild with it. That aero already looks like it takes you out of SSM, but you may be able to trim it to class size. There are some of the fastest SSM cars in the nation on this forum if you're interested.
Yes, forced in induction is planned, eventually. The reason I'm not concerned about classing is pretty simple. I'm not a good enough driver to compete at the pointy end of the national level, and I have no plans to ever take it to nationals. Having read the rule book over and over, XP has the exact same aero rules as SSM. Also, the tires, being non DOT put me straight into a prepared class. Maybe some day if I change my mind, I'll make a smaller wing. I've read through a couple of the SSM threads, and I'll definitely be taking a page from their book.

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Originally Posted by acedeuce802 View Post
If you haven't found these already, check out Oregon State's thesis archive. Their aero thesis' are top notch.
I have not found those yet! Looks like I have more reading material for today (since it's raining and the NB is still occupying the garage).

Quick update on what happened yesterday.

Got my alumalite from the local sign shop. It will be used to build my front splitter.



I also pulled the driver side headlight assembly out. It doesn't look too bad.

Attached Thumbnails
Autocross Class Unknown - An exercise in not caring-20160322_120050%25201_zpsws9xabbq.jpg   Autocross Class Unknown - An exercise in not caring-20160322_175326_zpsavxoch9y.jpg  

Last edited by ChasB; 03-27-2016 at 07:42 PM. Reason: pics
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Old 03-23-2016, 11:07 AM   #5
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"The best things come out of Iowa,"

If you ever make it over to the Eastern Iowa SCCA autocrosses, I'll make sure to say hi!
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Old 03-23-2016, 12:05 PM   #6
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https://ir.library.oregonstate.edu/x...dle/1957/48034
Aerodynamic undertray design for formula SAE

I feel like there's more, but I couldn't find them. Check the Honors Archive.
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Old 03-23-2016, 05:07 PM   #7
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Originally Posted by ChasB View Post
Yes, forced in induction is planned, eventually. The reason I'm not concerned about classing is pretty simple. I'm not a good enough driver to compete at the pointy end of the national level, and I have no plans to ever take it to nationals. Having read the rule book over and over, XP has the exact same aero rules as SSM. Also, the tires, being non DOT put me straight into a prepared class. Maybe some day if I change my mind, I'll make a smaller wing. I've read through a couple of the SSM threads, and I'll definitely be taking a page from their book.



I have not found those yet! Looks like I have more reading material for today (since it's raining and the NB is still occupying the garage).

Quick update on what happened yesterday.

Got my alumalite from the local sign shop. It will be used to build my front splitter.



I also pulled the driver side headlight assembly out. It doesn't look too bad.

That aero is not legal in xp or any prepared class. I don't know the mod rule set for aero.
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Old 03-23-2016, 06:58 PM   #8
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If you ever make it over to the Eastern Iowa SCCA autocrosses, I'll make sure to say hi!
For sure. Usually the farthest East I make it is Osky, but there may be an exception to that.

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Originally Posted by acedeuce802 View Post
https://ir.library.oregonstate.edu/x...dle/1957/48034
Aerodynamic undertray design for formula SAE

I feel like there's more, but I couldn't find them. Check the Honors Archive.
Thanks! Looks like there's some good stuff in there.

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Originally Posted by guttedmiata View Post
That aero is not legal in xp or any prepared class. I don't know the mod rule set for aero.
Nope, it's not. If I were concerned about it being legal, I would make it smaller. I guess I should have worded that post "the tires put me in at least a prepared class."


Another update from today. It stopped raining long enough for me to get out and do some body work.

This is what I had to start with. Some metal blocking the headlight assembly from going down.


So I did a little finessing with my 4 pound deadblow and a 4 ton capacity come along hooked up to a tree. This is the end result. It's not pretty, but it doesn't really need to be either.



Next up was fitting the semi-straight fender that I obtained.


Lastly, I threw the hood on for a test fit.



Then it started raining again. At least the day wasn't a total waste. It's supposed to sleet tomorrow, so I doubt I'll be able to get a whole lot done. I do hope to have the hood and headlight assembly all buttoned up by then.
Attached Thumbnails
Autocross Class Unknown - An exercise in not caring-20160322_175326_zpsavxoch9y.jpg   Autocross Class Unknown - An exercise in not caring-20160323_145637_zpsfoh6u0c2.jpg   Autocross Class Unknown - An exercise in not caring-20160323_145938_zps1gh7kxjk.jpg   Autocross Class Unknown - An exercise in not caring-20160323_154629_zpsptt6d92o.jpg  

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Old 03-24-2016, 05:49 PM   #9
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Looks like A Mod aero to me. Can't go above the windshield by more than 6" and can't be wider than the car. The mirrors on the doors don't count, more would door handles, rub strips, or any of that.

EMod aero is no wings. Just a spoiler.
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Old 03-24-2016, 05:54 PM   #10
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Also..... go buy a welder. Go get a decent 110V gas MIG setup and a bunch of drop angle iron. Go to town building picture frames and such. Do destructive testing on anything you think you did well.

You'll find having the ability to weld is pretty awesome when it comes to making a car lighter.
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Old 03-24-2016, 07:28 PM   #11
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Looks like A Mod aero to me. Can't go above the windshield by more than 6" and can't be wider than the car. The mirrors on the doors don't count, more would door handles, rub strips, or any of that.

EMod aero is no wings. Just a spoiler.
Except that he doesn't have the required rollbar for AM, so he's not legal for any SCCA class.
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Old 03-26-2016, 01:51 AM   #12
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Looks like A Mod aero to me. Can't go above the windshield by more than 6" and can't be wider than the car. The mirrors on the doors don't count, more would door handles, rub strips, or any of that.

EMod aero is no wings. Just a spoiler.
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Originally Posted by boileralum View Post
Except that he doesn't have the required rollbar for AM, so he's not legal for any SCCA class.
You are both correct. I will be running in XP locally, and since I don't plan on taking the car to nats, it doesn't really matter. Knowing some of the other cars that run in XP in this area, I don't really stand a chance at winning the class (purely based on power). If I start winning and they bump me to AM (because catchall), so be it. This year is really just a development year anyhow. If I decide to conform to a ruleset, I'll do it in the future.



Update from today:


Got some temporary bodywork on until I can find some suitable red replacements.



The only reason my driver side headlight is cocked is because the bracket got tweaked when the PO decided to test the strength of a concrete barrier.

And got my HF tire trailer mostly put together, and started mounting my hitch today (but didn't take pics).

Ride height finally adjusted to 4.25" in the front and 4.5" in the rear. I have yet to check with the Hoosiers, but it should be close.



To do list:

Get seat mounted
Alignment
Final tire clearance
Paint fenders / bumper to match
Mount trailer hitch
Finish up sway bar end links
Brake pads/rotors/calipers/fluid
Clutch master/slave
Radiator
Other stuff I'm forgetting at the moment.
Attached Thumbnails
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Last edited by ChasB; 03-27-2016 at 07:51 PM.
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Old 03-26-2016, 08:40 PM   #13
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To help others earn tire and brake contingencies because I'm there anyway.
This is precisely the reason I'll be running in XP with the local SCCA group. I don't stand a chance in winning, but I have friends that can win contingency money... and their cars *are* competitive in the class. Really, XP is sort of the catch-all for non formula cars that don't really fit into any other category/class in our region. We even have a guy that runs an electric powered miata in XP (max torque at 0RPM, yes please!).

I have lots of things to get done before even starting on that wing, though. It might be mid season before I get it on the car.
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Old 03-26-2016, 08:43 PM   #14
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In for pics and details of the electric Miata.
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Old 03-27-2016, 02:29 PM   #15
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Some of your pics seem to not be working.

I like the idea of just building the car you want though. Too often people build a car that will fit a class, but it's not really the car they want. If you're just planning to run on the local level it is far less important because you're just out there with your buds having fun.
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Old 03-27-2016, 02:37 PM   #16
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Some of your pics seem to not be working.

I like the idea of just building the car you want though. Too often people build a car that will fit a class, but it's not really the car they want. If you're just planning to run on the local level it is far less important because you're just out there with your buds having fun.
Yes. Build the car you want. It's crazy to think someone would build anything else, but I've seen in.
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Old 03-27-2016, 02:40 PM   #17
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Originally Posted by ThePass View Post
Some of your pics seem to not be working.

I like the idea of just building the car you want though. Too often people build a car that will fit a class, but it's not really the car they want. If you're just planning to run on the local level it is far less important because you're just out there with your buds having fun.
What a stupid idea. Don't be so disrespectful. You might hurt someone's feeling by not following the rules.
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Old 03-27-2016, 03:56 PM   #18
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Yes. Build the car you want. It's crazy to think someone would build anything else, but I've seen in.
Yeah we get quite a few calls each week from guys new to the sport not yet familiar with all the rules who assume Stock class is where they should go just based on ease of entry. The conversation usually plays out that they realize that a car built for stock class is a car that nobody wants to have, which they would never choose to build if rules weren't the determining factor. I always try to point them to STR which may have a higher cost to build in the end but allows the full range of basic wheel/tire, suspension and I/H/E options that most enthusiasts would naturally choose.
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Old 03-27-2016, 07:24 PM   #19
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Originally Posted by ThePass View Post
Some of your pics seem to not be working.

I like the idea of just building the car you want though. Too often people build a car that will fit a class, but it's not really the car they want. If you're just planning to run on the local level it is far less important because you're just out there with your buds having fun.
Thanks! I'll fix that in a bit... Evidently Google Photo doesn't like being linked externally.

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Originally Posted by ThePass View Post
Yeah we get quite a few calls each week from guys new to the sport not yet familiar with all the rules who assume Stock class is where they should go just based on ease of entry. The conversation usually plays out that they realize that a car built for stock class is a car that nobody wants to have, which they would never choose to build if rules weren't the determining factor. I always try to point them to STR which may have a higher cost to build in the end but allows the full range of basic wheel/tire, suspension and I/H/E options that most enthusiasts would naturally choose.
I agree, STS/STR is a pretty good option for people that want to do "the basics" with their Miata. It's just the crazies like me that have additional needs.

On a semi-related note, I have some question's about how you cut your front fenders on the car that's in your sig. I'll PM you about that, though.


Quote:
Originally Posted by patsmx5 View Post
Yes. Build the car you want. It's crazy to think someone would build anything else, but I've seen in.
That's why I'm doing it!


Update from today:


Got the hitch mounted... What a pain. I found out that my driver side "frame rail" is tweaked a little bit. The hitch still fits, but it definitely made me re-think my goal of making it quickly detach for racing. Oh well, it's extra weight, but at least it's in a better spot than up front and way high.

Here are the passenger side nuts on a schtick


And the driver side


And here it is all buttoned up on the ground.


Yes, I do have a sticker that says slowcarfast in a Mazda-esque font.
Attached Thumbnails
Autocross Class Unknown - An exercise in not caring-20160327_162222_zpshbkgjou5.jpg   Autocross Class Unknown - An exercise in not caring-20160327_162214_zpsbuntpkaq.jpg   Autocross Class Unknown - An exercise in not caring-20160327_162907_zpsveuwlg5p.jpg  
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Old 05-15-2016, 10:26 PM   #20
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Today was the first event I ran on the slicks, and all I can say is holy crap. I placed 10th overall in raw time in a field of 55. I haven't really done anything to the car since my last post other than get it aligned.



In other developments, I think I've decided to go ecotec with this car. Not because it makes the most power, or is way lighter than the BP, but because it fits my power goals, is easy to source if (when?) a rod decides it wants to meet the outside world, and is fairly inexpensive. Quick note that the Lotus Elan that placed 6th is one of the factory built race cars from the 60s. I don't feel so bad about being a half second slower than him considering his car weighs close to 800 pounds less than mine (including driver) and he probably makes 50 - 60 more powers and torques than I do.

On an even more positive note, I placed higher than the infamous jeep (which placed 24th). Though, I'm pretty sure it wasn't running quite right.
Attached Thumbnails
Autocross Class Unknown - An exercise in not caring-80-screenshot_2016_05_15_at_7_37_09_pm_24757cdf5004912e32f2a44211f212f6552f5e05.png   Autocross Class Unknown - An exercise in not caring-80-165034d1443040348_internal_engine_mods_small_aero_jeep_2_fac15f68aae978c2ec0d5e411581e3a3d179.jpg  
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