Bob Hall is considered by some to have seeded the idea for the Mazda MX-5. In 1979, When Mazda managing director, Kenichi Yamamoto asked him what car they should build next, Bob replied "A low-priced, open-bodied sports car." He drew a sketch which marked the beginning of Mazda’s iconic Roadster. He was very active on the Miata.net forums from 1999 to about 2002, and I captured some nuggets that interested me here. 

On having a 2.0 engine in the NA/NB

When the 1.8 came up, I would have fought hard on the plan to retain the 1.6 and add a 2.0 to supplement (rather than replace) the 1.6. That would have had a 2.0 FE engine with larger brakes and 195/50 15 tires on suitable wheels and suspension to suit.

As for the query as to if it's time for a 2.0 litre engine, I say no. If anything it's well past time. We pitched a 2.0 litre back in mid-1990 as part of what became the NA8B, suggesting the 1.6 remain as it was launched as he entry level Miata, with a new 2.0 added to the range rather than a 1.8 replacing the lot. From very early on the Miata was referred to internally as 'LWS' for LightWeight Sports. With a basic understanding, if not a first-hand historical perspective upon which to draw on, this worked pretty well to help sell the concept and to reinforce in the development team's collective mind as to what the car's priorities were. However it brought with it a ton of baggage we Westerners weren't aware of from our not living in the Japanese car market. In Japan there used to be a huge tax jump on cars when the engine went over 2000cc (the rate effectively tripled if you went 1cc over), and as a result 2.0 litre cars were seen as the 'top end' of the mass market. When we proposed the 2.0 litre Miata in Hiroshima, the locals argued that we didn't know a thing about sports cars and that "a 2.0 litre car couldn't be a LWS". This despite the fact the car as proposed weight about 12kg more than a similarly-optioned 1.6 litre Miata and the engine was actually 1.1kg less than the 1.6. Any explanation or attempt to clarify ran straight up against a brick wall. Go figure.

On the Ideal Wheel and Tire Size 

If it were my car I'd be focusing on 195/50 15s. On an NA it's an optimal size as regards performance, weight (presupposing properly lightweight wheels and tires are selected), tire availability and price are concerned. NAs on 16s are edging past the point of diminishing returns because of the minimal performance benefits in relation to tire replacement costs and the fact the lower profile tires can leave wheels exposed to damage to a much greater degree when encountering potholes and the like.

On the Honda S2000 

The S2000 is a car I really, really wanted to like, but can't. The gearchange is great, the engine magnificent - on paper, and it's got Honda's S600 and S800 heritage under its belt. But I cannot stand the fact it's got more mechanical noise (and to me it is noise and not especially pleasant noise) than music out of the tailpipe. Despite the bragging rights of having an engine which revs to nine grand, the S2000 is no fun unless driven at WOT all the time.

On Why the Engine Was Cast Iron

Mazda had no aluminium-block engine in production when the Miata was under development, and the budget didn't allow for an all-new engine. It had to be done out of the parts box.As for Honda doing an aluminium engine and Mazda not, Honda is Honda, Mazda is Mazda. Car companies - even Japanese ones - have philosophies, personalities and biases. As well as different engineering budgets. Mazda kept the Wankel Rotary under continual development from the early 1960s, so that absorbed a certain amount of manpower and resources (physical as well as financial). Honda had no such 'sideline'. Additionally, Honda's available engineering facilities, staffing and program budgets have been and larger than Mazda's by a couple of orders of magnitude since the mid- to late-1970s.

Back in the days (late 1960s, early 1970s), Honda's technological base was coming directly from motorcycles where aluminium engines were more common than in passenger cars. Going even farther back to the early- to mid-1960s, Mazda used to use all-aluminum engines in the entire passenger car and light commercial range: the Carol 360, Carol 600, Familia 800, Familia 1000, Porter Cab and Bongo. The company encountered technical problems which equated to high warranty costs Mazda decided it didn't want to wear. Out went the alloy, in came nodular cast iron.

Weight savings on the bare block could be likely to have been in the 20 to 35kg range, though the basic configuration of the engine as well as the technology involved in manufacturing the block (e.g. sand- or high-pressure die-cast) would have had an impact on that figure.

On The 5 Speed vs 6 Speed 

Well, I prefer the feel of the five-speed to the six-cog box in an NB Series Miata. Considering the fact the overall ratios aren't dramatically different (as regards cruising speed and rpm at same), I don't consider the six-speed all that great. The six speed is as reliable - if not a little more so with internals made by Toyota - as the original five-cogger. I don't think the shift linkage is as delightful as the five-speed and a couple of other wags seem to agree. Basically the quality of gear-changes from the six-speed a smidgen balkier and not quite as direct feeling as the basic Mazda five-speed. Mind you, this is a little like saying Elle MacPherson isn't as good looking as Tyra Banks. I wouldn't throw either out of the passenger seat in the highly unlikely event I am ever offered the opportunity.

On Why There Was No Steering Adjustment

At the time the NA Series Miata was being developed (it was Mazda's first car with an airbag), the research data Mazda had did not support the idea that an airbag would provide proper protection for all occupants if the wheel's position and angle were varied, so Mazda engineering guidelines did not allow the combination of airbags and a tilt column till more research had been done. Which was after the Miata design had been locked in. By the time data supporting the fact that an airbag on a tilt column could protect the driver was collected, the Miata had been tooled and certified. Modifying the instrument panel structure and the car's black metal (the stuff out of sight) was uneconomic once the car had been tooled,in production and was selling well. The current NB Series car is based on the architecture of the original NA Series car. Development budget of the NB didn't include a surfeit of funds to allow a new steering column to be tooled and to completely redesign the behind black metal the dash to accommodate a new adjustable column (remember that Mazda was in gawdawful financial shape when the NB was being done), so it carried over the old non-adjustable one.

On The Chassis Power Limits 

Normally aspirated. The Miatas all about balance, and the formula was set up to highlight that. When the power goes up, the balance goes right down the gurgler. Depending upon the generation, when power starts to get near 115kW/155hp the chassis tune starts to go off key, and quickly. The NB8B/M2 2001 and later models have had changes to the chassis to accommodate the increased power of the variable valve timing engine, but the margin built into the chassis above that unit's output is not exactly generous.

On The Best Engine Swap for the Car

The reason for my fixation (it's not a fetish, at least as far as my definition of the word is concerned) is because the best Miata I've ever driven had an SR20DE living under the hood, lightly massaged with a set of Autech headers and cams, a MoTeC M48 engine management system and custom-built cat-back exhaust system. What a knock out! I've been keeping an eye out for a 1989-92 Miata in good shape, but with a tired engine. And I know how well the SR20DE works under the hood of 240SXes, since that's the way we've been getting our 200SXes down here since 1994. Hell, we even get the new S15 Silvia. Now if they weren't all turbocharged...

On The Miata V6 Prototypes and Lack of Commercialization 

Just for drill, what do you think the V6 Miata's chances would be if Porsche decided to adjust the Boxster's price down by three to five percent? Porsche has plenty of cushion in the margins to do that and swat a potential competitor like a fly if it so desired. There's a direct correlation to price and volume; as the former goes up, the latter goes down. The fact the Miata is sitting below things like the Z3 and S2000 (as well as Boxster) is its trump card. History has shown that when you control the entry-level spot of any market segment, you control the whole segment. If Mazda walks away from this position of power, somebody else will step in and the Miata will become just an also ran. Development lead times ensure this wouldn't happen overnight, but it could happen quickly enough that there would be no need for an ND Miata.

As you said, enthusiasts are excited about the prospects of a V6 (or more powerful) Miata. But don't lose sight of the fact the Miata is a car for enthusiasts which also must have mass appeal. If it gets focused too much towards the enthusiast marketplace it will go the way of the RX-7 in the 'States. And subsidizing the desires of a few for more power (as well as the additional chassis, tires and brakes to go with the added power) will disenfranchise the mass market which has adopted the Miata and makes it a viable business proposition. And in time that means no Miata.

So while I think the V6 is a great project, I'm not convinced it would be a great Miata. Especially if adopting it caused the car to drift from the mother lode it currently owns. Mazda's sold more than 609,218 Miatas (the count through July) and not because the vast majority of those people thought it was underpowered.

Well, since an eight can be wedged in, a bent six shouldn't be a problem. Three prime candidates would be Mazda's 3.0 liter single cam from the old MPV (the single cam - the twin cam's a smidgen too wide to go in without some tricky cutting), the Nissan 3.0 liter VQ as fitted to the Japanese domestic Cedric and Gloria, which is already set-up for rear-drive and the Suzuki 2.5 V6 as used in the Grand Vitara/Sidekick (although it would probably require conversion to a dry sump). The 1.8/2.0/2.5 K-series V6 is completely unsuited for use in the Miata since it was engineered solely for and produced in front-drive configurations. As for outfits doing V6 into Miata conversions, I don't know of a single company doing it commercially. People into such excess seem predisposed to eights.

On The Mazda Miata 1.9 MPS Concept 

A hopped-up 'MPS' Miata appeared at the Frankfurt Motor Show last month, with a 200 hp 1.9 litre four (normally aspirated) underhood. Mazda is going to make a short un of the cars, said to be 200 to 500, for the Japanese market. The small production run reflects the fact that the car is expensive to produce (insiders have hinted at a price starting in the 3,000,000 to 3,500,000 Yen range). But with the NC Miata (which will forsake the B-series engine family used in all Miatas - including the MPS - up to this point in time) only a couple of years down the road, setting up the MPS for volume production is not a sensible place to make the sort of major tooling investment needed to reduce the piece costs of things like the unique nose, fenders and engine components through higher production volume. In 1999 it might have made sense, but not at this late point in time.

On A Rotary Miata 

The car wasn't conceived as a rotary. Despite the fact the rotary is simple, lightweight and has few moving parts, the production of the engine is extremely labor-intensive, with final assembly almost totally done by hand. The rise in living standards - and wages - that has taken place in Japan since the 1970s means the Wankel is VERY expensive to produce, and not in keeping with the price targets which had been set for the Miata. At the time the car was conceived, the RX-7 was going like gangbusters and the idea of the Miata was to build a car that was different to the RX-7, not just a low-price substitute. So it was conceived as a simple four-cylinder car. With a GREAT exhaust note. The Miata's missing a rotary for the same reason Corvettes don't have sixes - it's what the team developing the car - and the company supporting the team - wanted. As for the difficulty of a rotary conversion, as a conversion done by an individual, it shouldn't be too tough. As a change that Mazda could make on the production line it'd require a wheelbase stretch to allow the engine to allow sufficient clearance between the engine and steering rack. Manufacturers have to make allowances for variance in build that somebody swapping an engine wouldn't have to concern themselves with. This is a prime example of one. It's fascinating for me to see all the interest in the rotary after it's been dropped from the US market. Too bad it wasn't able to garner as much support when it was still offered.

Mazda offered up an excellent rotary-engine sports car for enthusiasts, who didn't vote with their pocketbooks in sufficient numbers to keep the RX-7 alive. A rotary Miata wouldn't have fared much better than the RX-7 did. More out-of-the-box performance would have upped insurance costs (as was the case with the RX-7) as well as increasing the initial price. If you think a $20,000 Miata is expensive now, It's be prohibitive in 1990-92. Which is what you'd like would have cost. 

On The Miata Hardtop

The hardtop provides no more roll-over protection than the soft top does when erected. Early hardtops had no foam pad on the inside, and are in fact somewhat louder than the erected soft top. This is due to structural resonance bouncing off the roof inner surface rather than being partially absorbed by the soft top. The foam liner was added as a running change to help reduce this problem. Like the soft top, the hardtop is an unstressed component. If the hardtop were carrying structural loads, the rear window would pop out of its mountings as the body-structure flexed by any degree.

The top is able to dampen (slightly) some of the lateral movement of the windscreen header, but the primary reason behind this is that with the top up the visual contrast between header and sky is diminished. With the convertible top raised, the multi-component aspects of the top induce rattles which the single-piece hardtop doesn't have, thereby creating the impression that the hardtop has stiffened the car vis-a-vis the erected convertible top or with the top down.

The car's torsional rigidity was measured in all three planes (as a body-in-white as well as a completed car) with the top down, top up and the hardtop on and there were no appreciable differences in the figures.I don't question that it may feel stiffer, but this is much more an example of the placebo effect than one actually reducing the bending moment of the car, I'm afraid.

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With gratitude to Miata.net