MX-5 ENGINE-CONVERSION GUIDE
Atruly underrated chassis, the humble ‘hairdresser’s car’ is undoubtedly a driver’s car and has been credited as being the spiritual successor to the great British roadster examples of the ’50s and ’60s. The Mazda MX-5 is a car that many still sleep on, often dismissed for its small stature and capacity. Despite those unaware of the chassis’ potential, it has managed to amass a rather hefty cult following on our shores. These pocket rockets are regularly used as streeters and circuit cars, drifters and gravel warriors, which should really be no surprise to anyone who has actually looked into them. Weighing in at only a bag of feathers and making use of a go-kart-like wheelbase, they offer solid bang-for-buck driving and, with a few extra ponies pumped into them, can be a proper handful.
While the factory-offered 1600cc and 1800cc can be tickled up with the likes of turbos, superchargers, or even a wild naturally aspirated (NA) set-up, one of the more popular options nowadays is to rip the factory offering out in favour of a bigger-power option. To help you make the right choice, we’ve pooled all the information you need to consider about the chassis itself and the challenges you might face and got the inside word from those who have completed a few of the more popular swaps.
By far the most popular generation of MX-5, the ‘NA’ chassis is recognizable for its pop-up headlights and widesmiling front bumper. In total, 400,000 units were sold during its production run, which offered up both a 1.6-litre and 1.8-litre power plant, so there are plenty of them around in various trim levels. Despite the body being an allsteel affair with the use of an aluminium bonnet, the car’s small stature, measuring in at just 3970mm long and 1675mm wide, means that it tips the scales at just 980kg wet! It also has the benefit of a 0.38 drag coefficient, which puts it on par with the Toyota Supra, and makes it better than all generations of Nissan Skyline.
Factory-fitted independent double wishbone and disc brakes at all corners, along with sway bars front and rear, make for solid handling out of the gate and allow easy upgrading for the more serious of uses.
Solely a front-engined, rear-wheel drive platform, the original B6ZE(RS) 1598cc was ported over from the Familia range, and offered dual-overhead cams, electronic fuel injection with vane-type air flowmeter, and an electronic ignition system with a camshaft angle sensor instead of a distributor. It promised 86kW of fury at the motor, weighed 127kg full trim, and ran power through a five-speed manual box that was derived from those used on the Mazda 929/Luce. Designers were given strict instructions to “make it shift in as small a gear pattern as possible and with minimal effort”, to ensure it felt like a serious sports car contender.
From 1994 onward, the NA offered a more powerful 1839cc BP-ZE engine option that saw the introduction of factory-fitted LSD down back. The chassis was also braced to pass new side-impact standards — this can be identified by a track bar between the seat belt towers inside the car and between the front and rear subframes. Various trim options offered differences in suspension, such as Bilstein shocks, stiffer sway bars, and front and rear underbody spoilers, while a Torsen LSD was also offered. This new 1.8-litre ramped power figures up to 96kW and, despite increasing the base weight to 990kg — with the motor weighing in at 145kg — the extra power offset the increase and then some.