Spec MX5 vs Spec Miata

Typically, two of the costs an ambitious driver must contend with when moving up into a faster vehicle is greater complexity and a more finicky vehicle overall. Not always true, but true enough to keep drivers in the class they’re comfortable with. However, those happy with the Spec Miata design ethos can find that in its marginally pricier successor, the Spec MX-5. Mazda’s four pillars for Spec MX-5 specify affordability, reliability, tech-ability and fun to drive.

That said, the two cars have their own distinct characteristics. With Dave and Wyatt Couch giving us insight into their builds of their first-generation Spec Miata and their recently built Spec MX-5, we will learn how these two platforms compare from builder’s perspective.

Cabins and Build Constraints

Dave and Wyatt’s hurried installation of cage, suspension, and engine in their Spec MX-5 has been well documented in Speed News. All of this took only a few months, from mid-January to April, which might have been protracted if not for assistance from Mazda and Penske Racing.

The first order of business with building their NC was getting the cabin in racing order. With the assistance of MiataCage.com and a talented welder friend, they had their spec cage in place quickly. It required some assistance over a hectic weekend, but the assembly and preparation didn’t cause much cursing or throwing of wrenches.

One reason why the Spec MX-5’s cage installation went as well as it did was because of the increased space within the cabin. True, the NC-generation Miata is regarded as a little chunkier than its siblings, but its size makes a new cage simpler to put in place.

The Spec MX-5’s ergonomics are slightly better, which makes life easier for the more generously proportioned driver. Now, Wyatt is lean and fit like an ambitious driver ought to be, but he’s quite tall. Long arms have been an issue in his older car. He’s banged his elbows many times on his Spec Miata’s NASCAR bars, but the Spec MX-5’s cage is designed in part to avoid that. It has door bars that flare out, so it’s a little roomier at the sides.

More importantly for the lanky Wyatt, the additional cabin room makes it easier to lean the seat back. “My head’s almost touching in the Spec Miata, but the new car gives me a few inches between my helmet and the roof,” Wyatt reported. Better yet, the MX-5’s flat floor needed no cutting to position the seat correctly, unlike the older car.

One downside to the extra space, ironically, is that there is a little extra work required to separate the driver from the fuel cell in the newer car. The Mazda-supplied tin kit/parcel shelf must be added to keep the driver safely separated from the energy source, whereas the Spec Miata requires nothing of the sort. At least that extra time and weight is offset somewhat by the ability to scrap the NC’s OEM heater core—something not possible in the Spec Miata rulebook.

Engine and Electronics

Despite the Spec MX-5’s engine bay being a little larger, its 2.0-liter MZR motor looks a little more cramped in there. Wiring is more abundant in the Spec MX-5’s bigger bay, which has to house a forward-slanted radiator as well as a power steering system. Still, despite the clutter, it somehow seems neater and is easier to work around. “If you start removing sensors or playing with wires in the NC’s bay, it’s all pretty dependable. If you do that with the NA’s brittle harness, something inevitably cracks off,” Dave chuckled.

More room and newer parts outweigh the added complexity of the MZR, making an engine installation fairly simple. Interestingly, the tuning process is even simpler than a Spec Miata — although that depends on what you mean.

To get the most from the old car’s BP engine, “I’d adjust the cams, try different air-fuel meters, and fiddle with the fuel pressure regulator. With the FPR, I get a sense of what’s working by going off exhaust temperatures,” Dave added. It’s that simple, satisfying, analog tuning that can make a major difference. It only takes a few horsepower to eke out a car length on a straight when a good BP motor makes 120, after all.

The Spec MX-5’s MZR engine doesn’t accommodate tuners. The Mazda-supplied ECU is strictly controlled and designed to show signs of tampering to keep engine performance completely equal across the board. “Basically, everything runs off the ECU. We hooked it up and it ran—no issues at all,” Dave sighed. It’s taken some fun out of it for him, but he can rest easier knowing that other cars shouldn’t have a straight-line advantage over theirs.

However, there are some ways to engage the technically minded racers who’ve just picked up a Spec MX-5. Dave decided to run an optional AiM MXL data system, which provides them enough operating information to feel they’re playing a major part in monitoring the MZR. Like the engine, data systems are simple to install with this platform — all he had to do was hardwire it into the OBDII plug!

Suspension

Arguably, it’s the difference in rear suspension design that represents the greatest difference between the two cars. In the case of the MX-5, the suspension is a bit more complicated.

There are 10 links present in the Spec MX-5’s rear, as well as the mandated RX-8 spindles and axles. Those latter two took a trip to the junkyard to source, and though not a major hiccup, they do add to the time required. However, the biggest time sink at the moment is working around the additional arms and getting the car aligned as they’d like it.

“Trying to get the first alignment done took us about four hours,” Wyatt noted. Some of that was due to setting the cross weights — something they’ll not have to repeat for a while assuming nothing catastrophic happens. In the future, aligning the new car may take less than 45 minutes, or about as long as it takes them to get the Spec Miata’s wheels pointing in the right directions.

The reason being is the Spec Miata’s rear suspension, although simpler, features only one pivot/connection point on the lower rear arm. This means a bit of see-sawing since adjusting toe affects camber, and a counter-adjustment is always in order until the two settings are mostly correct.

In the case of the Spec MX-5, having two connection points on the lower arm allows for camber and toe adjustments independent of each other.

There’s also a lot of room to get underneath the car when a lift isn’t available—like the many times a change is needed at the track. A higher rear bumper makes the suspension easier to access—something Dave appreciates after years having to make last-minute adjustments under a very low, very hot Spec Miata.

When the intended specs are attained with the Spec Miata, the suspension arms are at the end of their range of adjustment. When the Spec MX-5 hits its marks, there’s usually a little room left in its range of adjustment. This wiggle room comes in in handy in the event of an accident that bends parts.

So it’s a tossup. There’s more to the newer car, but its modernity shouldn’t be confused with needless complexity. In fact, some refinement and newer tech can make life easier for the tuner, even if it might distance them somewhat from the vehicle. At the end of the day, both vehicles are about turning laps affordably and reliably, with as little headache as possible, and while these two take slightly different paths to achieving that aim, they ultimately end up in the same location.

Interested in checking out Spec MX-5 for yourself? You’ll find all the information you need on the series homepage.