New to Autocross Classes and MX5 Modding

Miata Parts, Intakes, Superchargers, Headers, Exhausts, Shocks, Springs, Sway Bars, Brake Kits, Autocross and track mods.
eluviis
Posts: 65
Joined: Sat Mar 24, 2012 8:16 pm
Location: San Diego

New to Autocross Classes and MX5 Modding

Post by eluviis »

Hello guys,

I just bought my 2011 MX5 Touring PRHT 2 months ago. I've been working hard on a mod list with future plans for the car. I have it all on a spreadsheet, but I haven't bought anything yet as I'm making sure I don't make ANY mistakes. I'll start buying when I have every part down to the "T".

I'm interested in Autocrossing the car in SCCA solo so I'm busy trying to read up and make sure that the mods I choose fit the car in the proper class/category. I just downloaded the SCCA solo rules and I 'm trying to make sense of it all.

Could you guys give me some advice as to what I can do to the car, and what I cannot? You can maybe tell me what class I will fit best in (based on the street mods I want) and then I can try and aim my mods to fit best in that class. Of course, I know I can run showroom stock or something like that, but I want to do suspension mods no matter what, so I guess a completely stock class is not going to suffice. Maybe the next class up?

Here's what I have in mind.

Car: 2011 MX5 Touring PRHT
Location: San Diego, CA

1. The car is a DD for now, so I must mod it accordingly - I'm not too worried about carb though.

2. I would like to do:
a. Suspension: Shocks or coilovers, sways, FTSB brace (maybe one for the back too.) - Not focused on chassis bracing unless my class requires it.
b. Muffler: Catback (or I could do header and midpipe too if it fits in the class I'll end up in.)
c. Intake: AEM/Mazdaspeed or KN.

3. If need it for the class I'm aiming at, I can consider a set of RPF-1's with the proper rubber.

4. I will not be supercharging as it doesn't fit my budget right now.

Now, based on those mods I want to do. What class do you guys recommend I aim for? And... based on the recommended class, am I missing something?

Like I said, I'm considering doing midpipe and header too, but I'm afraid it might put me in a class that will require me to do a bunch of other mods to be competitive. I could consider a tune a long with the full exhaust if that's the extent of it.

Thanks for any advice you can give me.
My car: The 1995 RallyWays Miata
morrisg
Posts: 128
Joined: Mon Nov 15, 2010 12:02 am

Re: New to Autocross Classes and MX5 Modding

Post by morrisg »

Based on your list of what you want to do, #2 mainly, it looks like you are heading for STR class. You'll need to do all of #2 and #3, plus a fender lip roll if you choose the largest wheels and tires allowed in the class (17x9 and 255/40x17). Read the Street Touring rules carefully and check with your local autox club to find someone knowledgeable about the class who you can discuss things with. One word of warning: if you intend to prep this car for a run at a championship then I would advise moving to a soft top which is about 80 lbs lighter. Plan on spending about $10k to fully prep the car. If that number sounds too high, then you should consider starting in a class that doesn't allow as many modifications.

If you're new to autox, you might want to run the new Road Tire class just to try things out and make sure you really enjoy the sport before spending all that money to prep the car. By all means, Have Fun whatever you choose to do with the car.
eluviis
Posts: 65
Joined: Sat Mar 24, 2012 8:16 pm
Location: San Diego

Re: New to Autocross Classes and MX5 Modding

Post by eluviis »

Thanks for the advice. I was speaking to RPMchris earlier today about this subject and he did answer a number of questions.

$10k does sound like a big number, but the main issue I see is that most of those mods I listed are things that I want to do to the car for normal street driving anyway. This would put me in STR whether I like it not. To be honest, I'd much rather start in a completely stock class with street tires - But I've been itching for a new exhaust and new suspension since the minute I bought the car.
My car: The 1995 RallyWays Miata
nc4me
Posts: 114
Joined: Sat Jan 19, 2008 6:40 pm

Re: New to Autocross Classes and MX5 Modding

Post by nc4me »

To be competitive in STR you would have to make your car not daily driver friendly. Just do the mods you want and realize you won't be winning in STR, but you'll have an enormous amount of fun daily driving. That's what I did and I wouldn't change a thing. 8)
2008 Galaxy Grey Miata Sport 5 speed: TDR2 Turbo Kit, Goodwin Racing Q exhaust, H&R front and rear sway bars, Tein Flex coilovers, Stock LSD added, and 17X9 Enkei RPF1's with 245/40/17 Dunlop Direzza Sport Z1 Star Specs
eluviis
Posts: 65
Joined: Sat Mar 24, 2012 8:16 pm
Location: San Diego

Re: New to Autocross Classes and MX5 Modding

Post by eluviis »

I see that you almost have to decide if you want a DD or a race car. - To be competitive. Haha. Unless you're willing to leave the car completely stock.

Kinda sucks because I already race on a racing sailboat and our boat happens to rate in a class where it's not very competitive. We race for fun, but it would be nice to be competitive at something.

I'd leave the car stock just to be competitive, but it doesn't change the fact that it's PRHT, therefore heavier. ..and that I really want better suspension and a better sounding exhaust!

Isn't there another, less-modded class between STR and showroom stock. Nothing at all?

Oh well.
My car: The 1995 RallyWays Miata
nc4me
Posts: 114
Joined: Sat Jan 19, 2008 6:40 pm

Re: New to Autocross Classes and MX5 Modding

Post by nc4me »

There are now two stock classes. One that allows race tires(the traditional class) and one that only allows street tires with a rating of 140 or higher(the new class). Then it jumps to STR. So you're either stock on street or race tires or in STR. STR is the in between. It's between stock and SP if I remember correctly.

I'm lucky. I have a local autocross club that is way better then SCCA and their rules are different when it comes to modifications. It lets me set up my car the way you describe you want yours setup(see my mods in sig) and it's competitive. If moving to the Tampa, St. Petersburg or Clearwater area is an option for you, you're welcome to join us! :D
2008 Galaxy Grey Miata Sport 5 speed: TDR2 Turbo Kit, Goodwin Racing Q exhaust, H&R front and rear sway bars, Tein Flex coilovers, Stock LSD added, and 17X9 Enkei RPF1's with 245/40/17 Dunlop Direzza Sport Z1 Star Specs
eluviis
Posts: 65
Joined: Sat Mar 24, 2012 8:16 pm
Location: San Diego

Re: New to Autocross Classes and MX5 Modding

Post by eluviis »

Ha! Funny you say that. I'm looking at your signature and it almost looks like you set up MY car. O.o I'd maybe do different coilovers (thinking H&R), but other than that, pretty much spot on!
My car: The 1995 RallyWays Miata
nc4me
Posts: 114
Joined: Sat Jan 19, 2008 6:40 pm

Re: New to Autocross Classes and MX5 Modding

Post by nc4me »

Careful about the H&R coilovers. If my memory is correct, they are not adjustable for stiffness, only for height. So if you get them and the ride is harsher then you expected you're stuck(you can't soften them). Although I did notice you're in San Diego and I'm pretty sure there are a couple of members here or on miata.net that have them. Maybe one of them can give you a ride in their car before you buy.
2008 Galaxy Grey Miata Sport 5 speed: TDR2 Turbo Kit, Goodwin Racing Q exhaust, H&R front and rear sway bars, Tein Flex coilovers, Stock LSD added, and 17X9 Enkei RPF1's with 245/40/17 Dunlop Direzza Sport Z1 Star Specs
eluviis
Posts: 65
Joined: Sat Mar 24, 2012 8:16 pm
Location: San Diego

Re: New to Autocross Classes and MX5 Modding

Post by eluviis »

Sounds like a good idea. The bottom line is that if I go with the H&R coilovers, the ride height's gonna be 13". Apparently, anything above that is not optimum for them. I kind of find 13" a bit on the low side. I was originally thinking going with something along the lines of 13.25 - 13.5" (My car is at 14.5" stock all around).
My car: The 1995 RallyWays Miata
nc4me
Posts: 114
Joined: Sat Jan 19, 2008 6:40 pm

Re: New to Autocross Classes and MX5 Modding

Post by nc4me »

Sounds like the tein flex would be perfect.
2008 Galaxy Grey Miata Sport 5 speed: TDR2 Turbo Kit, Goodwin Racing Q exhaust, H&R front and rear sway bars, Tein Flex coilovers, Stock LSD added, and 17X9 Enkei RPF1's with 245/40/17 Dunlop Direzza Sport Z1 Star Specs
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