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octavious Dork
8/23/19 1:46 p.m.

Well I already have a DD, and I have a long term project car.  What I want is a reliable, fun, manual, RWD, convertible.   Here is what I’d like to do with it:

  1. Multiple day road trips along great roads (my BIL did BRP and Skyline via motorcycle, stuff like that)
  2. Track day with a club or group. (Nearest tracks to me are Road Atlanta and Atlanta Motorpsorts Park each about 3 hours from me)
    1. A safer track day environment. I’m not sure I want to wheel to wheel yet.
    2. For instance I know BMW and Porsche clubs go to Road Atlanta for HPDEs
  3. Autocross (It looks like my region has most of the Autocross in Bristol or in Nashville each 2 hours from me) 
  4. Occasional school drop off and drive to work
  5. Other car stuff

My budget for the car $6000.  I'm willing to travel, and have been to Atlanta for my last two DDs.

I've narrowed it down to 5 cars, all of which I have seen listed at or under my budget.  I've searched here and elsewhere, lots of good information about failures, DIY repairs, mods, etc.  But I'm mostly interested in driving differences on track and autocross between the cars.  I also see a lot of discussion on the  

Porsche Boxster with IMS addressed 

Mazda Miata NC early model (discussions here do not seem to like the NC as much as the NB for track work)

BMW Z3, 2.8 or 3.0, perferably 3.0 

BMW Z4, 3.0i

Miata NB with the Flyin Miata turbo (I've never had a modded car to this level, or a turbo'd car at all)


GameboyRMH GRM+ Memberand MegaDork
8/23/19 2:03 p.m.

I would rule out the NC just because it's the weakest option here. Of the remaining options, the turbo NB will be a lot cheaper to run than the others, so if running costs are a factor you should go for that one. Performance-wise the Boxster will be the quickest up-front and has the most potential, and will probably be more reliable than the BMWs.

Rodan Dork
8/23/19 2:30 p.m.

At that price point, you're bottom feeding NC Miatas, but in the ballpark for a really nice, low miles NB.  I would be suspect of any turbo Miata at that price point.

Don't rule out the NC... it's a really good chassis, and in many ways a better street car than an NB.  With springs/shocks/swaybars, good tires and alignment, an NC will go pretty well around a track.  It's already got good brakes, just a pad swap from track ready.  It will be more expensive to add power than an NB

$6k is about what it costs to do a turbo NA/NB Miata properly, with all the supporting parts (clutch, ecu, injectors, cooling, etc), not including the bottom end.  Sure, everyone on GRM can do it for $175 and a six pack, but do you really want to drive someone else's $200 turbo job?  Finding a complete turbo car that's really sorted and won't need lots of attention at that price is going to be difficult.  

German cars are German cars... 

I would buy the nicest stock NB you can find for $5k or so, make some minor suspension mods, get a nice set of tires, and enjoy the hell out of it.  If you want to turbo it, it can be done on a budget, but do it yourself so you know it's right.

octavious Dork
8/23/19 2:48 p.m.

"German cars are German cars..."  smiley  Don't I know it.  My current longterm is a old 911. 


Prices I saw for NBs clean but higher mileage were $2-3k and add the FM kit is that doable?  There is a turbo NB with the FM kit near me with 70k miles for $6K but I have not heard back from the seller yet.  Other used turbo'd Miatas look pretty sketch.  


I also found this from an old post of Keith's about buying a used turbo'd Miata.


"Now, buying a used turbo Miata. You can get some great deals doing this. You can also buy some real turds. Here's what I'd keep in mind.

  • it's being sold for a reason. It probably has some unresolved issues which are contributing to the sale. Be prepared to go over the car top to bottom.

  • it's fairly common for them to pass quickly through several owners when the original modifier sells it. Partly because the new owners find it's not what they wanted, partly because something weird goes on and they can't fix it. So they tend to get rougher and rougher in a hurry, and the knowledge of what's been done tends to decrease at the same time. Again, be prepared to go over it top to bottom. It's pretty common for us to get an email with a photo of an engine bay asking "so, just what do I have here?"

  • if it has an aftermarket ECU, expect to have to learn how to tune it and sort it out. This is especially true of the cars described above. If you want full production car manners, you may have to change out the ECU as some of the older cheap stuff had a better reputation than was possibly deserved for anything but dyno runs. Also, ECUs age. The Link ECU from FM was a good unit with custom-written firmware, but the hardware is failing on them after 15-20 years.

  • if the car has some sort of jacked up fuel setup like a FPR with a stock fuel pump or a resistor on the coolant temp line, you'll want to deal with that.

  • if possible, get a car with an FM kit. I'm not just bragging on our brand here, it's because you can still get parts for it. Ebay specials, non-FM kits, small manufacturers - if you need something, you may not be able to get it. We support all of our turbo kits and have backwards compatible parts for them. The manifold/turbo/downpipe are all part of a system, so if you have problems with one you may have to change two or three if parts aren't available.

  • if possible, get records. Helps a lot when you're trying to solve a problem or get parts.

  • take a good look at supporting mods such as suspension or cooling. Good parts? Well installed? Or are the Mishimoto fans (run away from those) ziptied to the radiator? It's a good judge of how the car's been built and maintained."

Rodan Dork
8/23/19 3:10 p.m.

All of that is really good advice.

If you can find a clean NB for $2k, jump on it!  I paid about that for mine, but it was an auto and needs paint.  Fortunately, I had all the parts to swap in a 5 speed... paint, that's another story, LOL.  Nice, needs nothing NB drivers are $4k and up here (AZ)...  a little more for an NB2, which is what you really want.

FM has the most 'complete' turbo kits, but MK Turbo and Kraken are other good options for DIY turbos on a budget.  

z31maniac MegaDork
8/23/19 3:22 p.m.
Rodan said:

$6k is about what it costs to do a turbo NA/NB Miata properly, with all the supporting parts (clutch, ecu, injectors, cooling, etc), not including the bottom end. 

I think it's going to end up being more than that.

FM's base kit is ~$4200. And you haven't added a clutch, upgraded radiator or oil cooler, or the suspension/brakes/wheels/tires to handle the extra 70-85 whp. 

And we haven't even got to the safety equipment you'll need to track a Miata if you start out with something that is bone stock.


If you go with their custom spec kit, and all the options (which is what I would do), you're at almost $6300 without addressing everything I mentioned.

Fitz New Reader
8/23/19 4:04 p.m.

Of note I think BMWCCA doesn't allow convertibles at all at any of their HPDEs, PCA I think requires arm restraints last time I looked into doing a day with them.

I've got an NC and I think it's great for a dual purpose driver/track car. Putting a DE Compliant roll bar in one is not trivial though. It's much more of a car than a miata compared to a NA/NB. They've also never been in a nationally competitive position for AutoX which hurts the cachet. 

AutoX wise the NC is in the same classes as the s2k and ND at just about every turn so it's always going to be behind them, in STR trim they're very fun and easy to drive, in CS trim they're not super fun.

Track day wise again pretty easy to drive with springs/shocks. I've got the FM Transformer roll bar and have absolutely no top-end speed with the trunk off. Basically everyone has to lift to you let you by on a straight. When I took the car to Watkins Glen I left the top of the esses at 105 and was at 107 by the bus stop. It can also be pretty boring on higher speed courses (See Watkins Glen) but is a riot at others, AMP was pretty great, I'm guessing Road Atlanta is going to be somewhere in between.

Mine has been dead nuts reliable, only things I've had to change on mine that wasn't a wear item/preventative was an o2 sensor. Wheel bearings are cheap and the fronts are easy to change. I've done some silly stuff with it like going from MD to FL for a track day, did the SCCA Targa event in it. 

Comparisons to the other cars listed: I've ridden in a stock NB at a track day, it makes the NC feel powerful but still seemed really fun. My only experience with a turbo one was a guy that I was paddocked next to who had problems overheating, his was a hacked together ebay kit though. No firsthand experience with the others, I think I've only seen 1 z4 at a track day and it was a coupe.

BoxheadTim GRM+ Memberand MegaDork
8/23/19 4:08 p.m.

How tall are you? That's likely the important question when considering a Miata NA/NB. I'm 5'11" and I don't fit them overly well once I ended up sticking a rollbar in. The latter is a must for HPDE unless you're using the "hardtop loophole" with SCCA, assuming that still exists.

$6k for a a well built turbo sounds cheap, $6k for a badly duct taped together one is a lot of headache for the money.

Driven5 UltraDork
8/23/19 4:15 p.m.

I'm in a very simliar situation, and have decided on NC as my 3 season daily and motorsport toy.  Here are a some of the considerations I have taken into account:

1) Some clubs (BMWCCA) do not allow any type of open top cars at their track days. However, I require it to be a convertible, so that's a moot point.

2) The NC, Z3 (with factory bars), Z4, and Boxster from your list are all allowed by many/most clubs to run on track with only factory rollover protection.

3) The combined melon cracking proximity and broomstick clearance should both be superior with a Blackbird Fabworx RZ rollbar in an NC than any rollbar in an NB..

4) Depending on child size and age, NC Miata is the only option with both a manual airbag disable switch and lower 'latch' anchors from the factory. Still no upper tether, but the best of the bunch nonetheless.

5) Fear factor: If I pop a motor on a Boxster, and they do suffer from some sticky tire oil starvation issues, it's beyond totaled. If I pop a BMW motor, it's not quite totaled, but almost.  If I pop an NB motor, it's a few hundred bucks for a replacement...As long as it's internally stock. If I pop a motor on the NC, it's a couple grand and a weekend or two away from a nice 2.5L upgrade.

6) Since I'm out to have fun and not to win, I'd rather run less grip than more power to get the same liveliness at lower speeds. More power (and more prestigous brands) means more expensive consumables, as does things like staggered wheel/tire packages. Cheaper consumables means more track time.

As far as the driving experience, a Z4 is going to feel more GT than 'sports'...And while a Boxster may be a better driving experience than a (NB or NC) Miata with basic suspension upgrades, it's not enough so to overcome the other (IMHO) drawbacks.

bmw88rider GRM+ Memberand SuperDork
8/23/19 4:19 p.m.

So, I've had a few of the cars on that list and I would buy the NC for that purpose. 


3 reasons why: 

1. The German stuff is not well supported for track work. Great avenue cruisers, Track beasts were not in their DNA. 

2. 4-6K Z cars just have never proven reliable in my experience. 

3. the NC has a much better base to build off of if you want to. 


My cheap turbo NA (Sub $4K) is now a $10K car. Granted, I went a little nuts but that's more just because there are just a lot of that needed attention. 


Irregardless, Budget a roll bar as part of the project. That will be 800-$1K on up. 



octavious Dork
8/24/19 5:24 p.m.

My boss has a NC he said I could borrow next week when I am back from work travel. 


There is a 2.8 Z3 I will check out next weekend. 


And a new one, albeit older, Porsche 944? Those seem to fit as well.

BlueInGreen - Jon
BlueInGreen - Jon SuperDork
8/24/19 6:36 p.m.

In reply to octavious :

Shoot... it’s been a looong time since I saw a 944 convertible. Didn’t they only make a convertible version of the S2 and aren’t those worth $$$?

docwyte UltraDork
8/25/19 8:56 a.m.

Yes, BMW disallows convertibles at their track events, period.  PCA allows them with arm restraints, as long as the factory rollover protection is adequate AND you pass the 2" broomstick rule. 

It's much easier to find a 968 convertible compared to a 944 convertible but I wouldn't buy either.  I think the best convertible in the class for track work is an S2000 but you'd have to increase your budget to get one.

I stumbled into an NA8 FM turbo miata here for cheap, look up my build thread here on it.  I ended up selling it to another GRMer for a sweet deal once I figured out I wasn't fitting into it without cutting a hole in the floor so I could pass the 2" broomstick rule and track it.  He's put a pretty good amount of work into it, some are things that were upgrades that were nice to do vs needed to be done but it still had some needs...

I guess what I'm saying is make sure you have room in your budget to bring the car up to snuff, especially if you plan on tracking it.

amg_rx7 SuperDork
8/25/19 4:32 p.m.

NC or Boxster

Maybe a mustang if there’s a roll bar available 

I wouldn’t want to take a NB on a multi day road trip. Too cramped 

The Boxster reliability still worries me though. Wouldn’t touch a BMW for the same reason

ShinnyGroove Reader
8/25/19 9:52 p.m.

I built a turbo NA that I run at the track.  It’s plenty fast and loads of fun, but it seems like it’s always one tweak away from being where I want it.  Lately it’s been heat issues- had to upgrade the radiator, and next I’m putting hood vents in.  Having built one, I feel like I could tell a good turbo build from a bad one.  Without that experience, I would be really hesitant to buy someone else’s work.  There are a lot more ways to do it wrong than right.


There are a couple guys I see at track days who have NC’s that they bought when Skip Barber went under.  I’m really impressed, those cars are stupid fast and just about bulleproof.

KyAllroad (Jeremy)
KyAllroad (Jeremy) UltimaDork
8/25/19 10:40 p.m.

I built or owned a CSPish NA.  Then a monster NA.  Then an Ecotec NB.  Then an stock NC and an STR prepped NC.   Throw in my time in a relatives 3.0 Z-3 I feel I have a good feel for the genre of small two seat convertibles.  The NC really responds to some suspension work and a few mods to open up the engine breathing.

Three weeks ago I won the SCCA TT regionals in T4 at NCM and today I secured an STR class championship over a couple of prepped S2Ks and an ND.  The NC is a helluva car.

LanEvo Dork
8/26/19 6:56 a.m.

When did the BMW CCA ban convertibles? They used to allow them as long as you had rollover protection (broomstick test) and arm restraints. 

¯\_(ツ)_/¯ PowerDork
8/26/19 7:00 a.m.

Any particular reason MR2 Spyder didn't make the list?  You should be able to land a nice one within budget, or for a more exciting option one with a blown engine and a 2zz to swap into it.

BlueInGreen - Jon
BlueInGreen - Jon SuperDork
8/26/19 7:17 a.m.
pinchvalve GRM+ Memberand MegaDork
8/26/19 8:07 a.m.

I would second the MR-S. Amazing chassis, lightweight, and Toyota reliability. You can swap in entire engines or go the turbo-kit route. Plus, its not another Miata. 

That said, the reason there are so many Miatas is that they are good. If it were me, I'd buy the most rust-free Miata I could find for as cheap as I could so I had $ left to throw the FM catalog at it. 

Floating Doc
Floating Doc GRM+ Memberand SuperDork
8/26/19 8:29 a.m.

In reply to KyAllroad (Jeremy) :

Did I miss reading the details about this NC? Is there a thread on it?

octavious Dork
8/26/19 4:27 p.m.
¯\_(ツ)_/¯ said:

Any particular reason MR2 Spyder didn't make the list?  You should be able to land a nice one within budget, or for a more exciting option one with a blown engine and a 2zz to swap into it.


No logical reason, I just don’t like them. 

octavious Dork
8/26/19 4:30 p.m.
BlueInGreen - Jon said:

Could this be the answer to your question?



octavious Dork
8/27/19 10:23 a.m.

So after the advice here I've been looking at NCs.  


I've seen several with worn upper seat bolsters on the driver's side.  My concern with that is if a) if it is really just worn or the side air bag deployed, b) and replacing the seat.   Is it common for that area to get work and the seat split?  I assume it is from how people slide into and get out of the car.   

I did find some fairly niced priced cars with high mileage.  Several people in Atlanta selling ones because they just had kids.  

What do I need to look for besides regular used car stuff on these? 

What kind of power upgrades are available for these?  I saw FM Supercharger setup.  I also saw the GRM article on the 2.5 swap. But how common are either of those.  Also, can the 2.0 be tuned at all?  I've never had a car that you can tune so I know nothing about it. 

KyAllroad (Jeremy)
KyAllroad (Jeremy) UltimaDork
8/27/19 11:01 a.m.

In reply to Floating Doc :

No thread for it.  I bought it early this spring from a friend.  It's a 2006 Grand Touring with intake/header/exhaust/tune and MCS remote reservoir coilovers.  The car was originally put together by a fellow name Mike "Junior" Johnson.  I upgraded the brakes when I got it to Hawk HPS 5.0 pads and some fancy rotors that came with it.  I'm looking for seats right now as factory leather  NC seats aren't great.

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