7 Tips for Making Smart Miata Mods

Staff
By Staff Writer
Jan 20, 2021 | Mazda | Posted in Suspension & Handling , Restoration & Renovation | From the Feb. 2016 issue | Never miss an article

 

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VENUE: The most competitive place to race a truly low-dollar, 1.6-liter Miata is the SCCA’s Street Touring S autocross class. At The 2015 Tire Rack SCCA Solo National Championships, 63 drivers entered that STS class. A Honda CRX driver took top honors, but Andrew Canak drove a 1991 Miata to second place. TIRES: The high-performance market for 14-inch tires has dried up, but fortunately the Miata easily accepts 15-inch wheels–and they’re legal for the Street Touring class. If you can’t find something good on the used market, places like [Good Win Racing](http://good-win-racing.com), Discount Tire, Tire Rack and König offer a great selection of lightweight, inexpensive wheels–some priced near the $100 mark. A 15x7-inch wheel is good, but a 15x7.5-inch wheel takes full advantage of the rules. The top cars at the 2015 Solo Nationals ran on Bridgestone Potenza RE-71R tires, and Tire Rack charges about $120 each for the popular 205/50R15 size. The BFGoodrich g-Force Rival S, the other contender at Nationals, sells for just a few dollars more. According to Tire Rack’s Chris Harvey, there’s no need to shave either one. The Toyo Proxes R1R, now available with a 200 treadwear rating, retails for a little less than $120 each in a 195/50R15–the hot size for Miatas in that particular tire. The Toyo was popular in the past, but a rule change legislated it out of the class. The new treadwear rating has now returned it to the street tire fold. Have less cash to spend? It may not have a win at the Solo Nationals, but the new Kumho Ecsta V720 retails for about $100 apiece. DIFFERENTIAL: To help those tires grip the road, you’ll want the optional viscous limited-slip differential. If your car doesn’t have one, [Treasure Coast Miata](https://treasurecoastmiata.com) can hook you up for about $300. (A more effective Torsen differential became available starting with the 1994 model year, but it’s not legal for the STS class. Treasure Coast Miata sells a Torsen conversion for about $850, and it includes the complete differential plus the axles and driveshaft needed to complete the swap.) SHOCKS: For autocross–or really any performance driving–you’re also going to want good shock absorbers. Good Win Racing offers the popular Koni dampers for less than $150 each. SPRINGS: Stiffer springs that lower ride height are also part of the equation. Off-the-shelf lowering springs start around $200. Adjustable coil-over kits allow more suspension tuning, but that comes at cost. Ground Control’s popular Miata coilover kit retails for about $1250, and that includes the Koni dampers. ANTI-ROLL BAR: We’d also go bigger on the front anti-roll bar. Racing Beat’s popular hollow front bar usually retails for a tick above $150. It’s available directly from its maker as well as retail outlets like Good Win Racing and Moss Motors. Just about everyone else in the Miata market offers suspension upgrades, too, including Flyin’ Miata, Moss Motors and Mazdaspeed Motorsports Development, the marque’s own competition arm. POWER MODS: If you have any budget left, then start looking at things that add power. Cold-air intakes, free-flowing exhausts and ECU upgrades are popular and legal in the STS class, and the usual suspects can help.

 

 

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Comments
RedGT
RedGT Reader
5/16/16 2:09 p.m.

If you've been autocrossing in sub-par cars and think you might be pretty good, this has got to be the most budget-friendly way (other than picking up a codrive) to get into a "full-prep" car and find out. Mine cost $7k including buying most of the parts new all at once (ouch) and starting with a really nice $3500 chassis (that was not at all necessary).

There is enough prior knowledge out there that you can do a little research, install all the parts, and right off the bat be able to fight for the local win and get into the trophies at Tours/Pros assuming you can, in fact, drive.

Mr_Clutch42
Mr_Clutch42 SuperDork
5/16/16 9:45 p.m.

I'm likely to move to a well prepped Miata after running lightly prepped cars in the past (including an E36).

c0rbin9
c0rbin9 New Reader
5/17/16 12:02 a.m.

Is there a year/trim to have for an STS Miata? Does it matter?

Thinking of dispensing with my neverending search for the mythical clean E30 and just picking up a cheap Miata instead.

NickD
NickD Dork
5/17/16 5:25 a.m.
c0rbin9 wrote: Is there a year/trim to have for an STS Miata? Does it matter? Thinking of dispensing with my neverending search for the mythical clean E30 and just picking up a cheap Miata instead.

I would say '94-'95. It's still the classic lighter NA chassis cars. But it adds a bigger more powerful engine, bigger brakes, extra chassis bracing and a stronger rear differential with Torsens available, all while staying OBDI.

RedGT
RedGT Reader
5/17/16 8:53 a.m.

I have a different opinion - specifically for STS competition, buy the nicest one you can find in either engine size.

To go out and have fun, any 90-97 without a Torsen works (Torsen goes to STR)

To get super serious, avoid 96-97 because of issues maintaining OBD2 functionality with megasquirt and other tuners, like you said. But I'm 3 years into this and I can't justify the cost of a megasquirt yet. Last weekend I was solidly within "just drive better you idiot" distance (0.017 and 0.24 sec) of the reigning prosolo champ, and I have no tuning system installed except a chipped ECU to raise the rev limit.

90-93 - VLSD, less power, less weight.

94-95 - Open diff, more power, more weight.

Suspension stuff you do to them is essentially identical between the two.

90-93 are the only Miatas that have actually won nationals in STS. But then...one blue Miata driven by andrew canak is the only miata that has actually won nationals in STS.

A friend has just built a '94 to the limit of the rules and I look forward to trying it against my equally built '90 but right now the guy is in just-had-a-baby limbo and not racing for a bit.

KyAllroad
KyAllroad UltraDork
5/17/16 9:01 a.m.

A friend has a '91 STS car built very close to the limit of the rules. It's exceptionally quick and usually our fastest road tire car locally. My '97 suffered badly on a tight course due to the lack of a torsen diff.

My vote for the best STS car would be to get a 1.6 car with the VLSD diff. Weight and traction will trump raw power in autocross.

Bear in mind, built to the limit of the rules the car will have no radio, no AC, race seats, MS tuning, 750/550 springs, and Konis race shocks. It will not be a pleasant DD car anymore.

NickD
NickD Dork
5/17/16 9:08 a.m.

Huh, I guess I have the hot ticket for STS and didn't realize it, with my 1990 1.6L with VLSD. In fact, I was told several times (on here even) that the '90-'93 was rubbish for autocross and I oughta sell in and get either a 1.8L NA or an NB. Granted, mine is a B-Pack, so it has all the heavy stuff you wouldn't want for an STS car. And now I'm running it in C/SP to already better results.

RedGT
RedGT Reader
5/17/16 11:41 a.m.

Yeah, you do. It's also a hot ticket for CSP when fully built. I don't know where all the 'Buy a 1.8' rhetoric comes from in this case. On the street? Sure buy a 1.8 or an NB. Plan to leave it bone stock? Ok, buy a 1.8 or NB. Have a cranky spouse that wants it to feel like a 'real car' from this millennium? Definitely buy an NB.

But if you plan to start throwing coilovers and bolt-ons on it and go seriously autocrossing? Then a 1.6 NA is perfectly adequate and in specific cases arguably better.

Canak's is a '91. At nats last year the next highest placing Miatas were 90, 90, 92, 91, 92, 92, 90, etc. The first 1.8 car was 38th place. Now, I am not saying 1.8's are bad. There are plenty of them running around doing very well in STS too, they just didn't happen to make it to nationals. What I am saying that 1.6's can totally get it done.

I am actually anxious to try with the 1.8 as mentioned because the newest tires have great longitudinal grip and the required open diff will be less of a handicap. But "it miiiiight be better" does not correlate with "abandon 1.6 and buy 1.8 right now!" that I often see and that you encountered. I don't get it.

cmcgregor
cmcgregor HalfDork
5/17/16 11:43 a.m.

In reply to NickD:

What do you have on your car that puts it in CSP? Just curious.

STS is a lot of fun, but is really the only "home" where a 1.6 car is the one to have (arguably). Getting a 1.8 opens up ES, but STR is pretty tough for an NA. General consensus seems to be that a 1.8 car is a "better" street car, but in reality it's just slightly less slow than a 1.6.

NickD
NickD Dork
5/17/16 11:50 a.m.
RedGT wrote: I am actually anxious to try with the 1.8 as mentioned because the newest tires have great longitudinal grip and the required open diff will be less of a handicap. But "it miiiiight be better" does not correlate with "abandon 1.6 and buy 1.8 right now!" that I often see and that you encountered. I don't get it.

I do have a 2000 BP-4W that I yanked from a junkyard that will be getting overhauled, built up and put in the car this winter, just because I would like a little more power. Although I autocross my car, it does see primary use on the street so ~160 crank horsepower would be nice

cmcgregor wrote: In reply to NickD: What do you have on your car that puts it in CSP? Just curious. STS is a lot of fun, but is really the only "home" where a 1.6 car is the one to have (arguably). Getting a 1.8 opens up ES, but STR is pretty tough for an NA. General consensus seems to be that a 1.8 car is a "better" street car, but in reality it's just slightly less slow than a 1.6.

I have the 15x8" Jongbloed wheels, a FM/Cannon rear subframe brace and a high-flow catalytic converter, all illegal for STS. I'm not actually building my car with any class in mind, I just build it into my image of a fun street Miata and let it fall in whatever class it falls in. The advantage to being in C/SP in my region is the only other car in C/SP is a '92 Miata, so it's a close dogfight.

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