OPEN-HEART SURGERY

MX-5 EN­GINE-CON­VER­SION GUIDE

NZ Performance Car - - Contents - WORDS: JADEN MARTIN PHO­TOS: SUP­PLIED

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.

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