Thursday, July 02, 2009

The More I Learn

The more I learn about Mia, my Mazdaspeed Miata,* the more I regret buying her, rather than a third-generation (NC) MX-5. Of course, I long ago personified her and assigned her a gender, so I guess we're stuck with each other for a while.

* Not just Mia. All the MSMs.
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3 comments:

  1. Unknown9:07 AM

    What are the regrettable bits about Mia?

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  2. Michael10:37 AM

    Well, that question requires a long answer, but here's the short-ish version.

    Most of these issues, I think, go back to the way the Mazdaspeed Miata was developed. The first-generation (NA) MX-5 Miata was designed in the late 1980s to be an inexpensive sports car that recalled the British roadsters of the '60s and '70s but was reliable and whose top didn't leak. The NA was first sold in '89 as a 1990 model with a 1.6-l engine. Over the first 7 years, the displacement was increased to 1.8 l, and some additional chassis bracing was added for improved stiffness---open-toped cars are notoriously floppy---and to meet new side-impact regulations

    The second-gen (NB) Miata debuted for MY 1999---there was no 1998 Miata---was far from all-new. The bodywork and interior were different, but the chassis was essentially that of the NA, with recontoured rear fenders and a few other changes. Oh, and some more braces were bolted on.

    The NB was facelifted in MY 2001, and the engine was given variable valve timing and a higher compression ratio.

    The MSM came out in 2004, and it is essentially just a 2001 Miata with the lower-compression engine from the 1999 and a fairly crappy turbo kit. The MSM also has a number of higher-performance or heavy-duty components.

    So, the MSM is basically 70% the same as a the 1980s-designed 1990 Miata; it has a bored-out version of the same engine, some new bodywork, a new interior, some bolt-on braces, and the aformentioned boost kit. So, the car is something of a kludge: an old design with a number of band-aids stuck to it.

    Here are some ramifications of this evolution:

    The chassis is still quite flexible. It was floppy when it held a 120-hp engine, and, although it's been braced, it's still floppy with 178 hp on tap.

    The car is heavy. OK, a curb weight of 2530 lb is much lighter than any (non-kit) sports car other than a Lotus, but it's still pretty beefy for such a small car. The engine block is iron, all the bodywork except the hood is steel, and all the braces add a lot of weight.

    The turbocharger is a cheap, non-ball-bearing model which doesn't spin that freely or produce much power. Additionally, very little boost is produced below 3500 rpm, when it all appears out nowhere, which makes the car difficult to drive smoothly. The main problem with the turbo kit is the ECU, however. It has a lot of little flaws in its programming, which lead to somewhat inconsistent operation of the engine and poor adjustment to any modifications made to the car. The ECU can't be reprogrammed, so the only real way around this problem is to replace the ECU with something like a Hydra Nemesis, but aftermarket ECU's aren't allowed to return OBD II codes, so I could never pass emissions inspections with one in the car.

    Another ECU problem: The second radiator fan will not come on unless the air conditioning is on, no matter how hot the engine gets. So, if you are autocrossing or tracking the car on a hot day, you have to watch the engine temp carefully and run the heater. There's a way to circumvent this design flaw, but I shouldn't have to do that. (By the way, the temp gauge is not a real gauge, sadly: it only has 3 positions: Cold, about right, and hot.)

    The heating vents into the footwells can't be closed all the way, so your feet are always being warmed slightly. This isn't a huge deal, but it is quite an irritation.

    (End of Part 1)

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  3. Michael10:37 AM

    (Part 2)

    By contrast, the third-gen (NC) Miata is qan all-new design. It has a modern chasssis, a modern suspension design, and a modern ECU The engine is am aluminum-blocked, high-compression, 2.0-l unit with variable valve timing, and it puts out 166 hp. That's not quite as much power as the MSM's mill, but it's much easier to use, and it doesn't have all the complication and headaches of a turbo system.

    In addition to the engine block, aluminum was also used in the suspension arms and trunk lid to save weight. When comparably equipped, a 2006-2008 NC is about 30 pounds lighter than my car (and about 20 pounds heavier than a non-turbo 2005 Miata). That doesn't seem that much lighter, but consider that the NC is longer and wider, has a larger interior, has 2 more airbags, has a semifunctional rollbar and is much, much stiffer.

    The major downside to the NC is the unforgivably high and soft suspension setup. This problem can be completely solved for with new anti-roll bars, dampers, and springs, for around 1000 $.

    So, there you go. I should have gotten an NC.

    But, like I said, I'll be keeping Mia for a while.

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