Chris' 'TREX-07' - 1987 Series 4 RX-7 TII

Story and Photos: Ben Winstone

Most people would agree that when you set out to build a neat street car, no doubt problems will be encountered. Yet when you find out the number and type of problems Chris faced during the build of his 1987 Series 4 RX-7 Turbo, its a wonder he didn't go insane and end up in a padded cell wearing a straight-jacket.

Originally purchased in December 1999, the 'seven' was naturally aspirated running the six-port EFI motor and featured an immaculate body and low kilometres, yet Chris had a vision that a few things could be tweaked. However that vision didn't last long, within the first few weeks of ownership, the car developed a noticeable power loss at around 3800rpm.

Dropping it off at the local Mazda dealer, Chris was assured the problem would be rectified, and two weeks later he was cruising it out of the dealership, being told the problem was fixed. After giving it a bit of stick, the power loss was still there, unimpressed, he returned and seeked an explanation. The mechanic was of no help however, not really knowing what was causing this mysterious problem and demanded another week to fix the problem. It was eventually diagnosed that the secondary actuators on the engine had seized, not allowing it to open properly, flooding the engine and causing the lack of power. The mechanic overcame this by wiring the actuators open, giving good top-end power, yet compromising low-end. Chris was keen to get the car back on the road and thought he could live with this compromise.

For once, the problem seemed to be solved, and the car was happy to rev out to its 7500rpm redline, however it was too good to be true and within a few weeks, the car developed the pained stuttering once again. Beginning to get tired of Mazda's supposedly ability to fix the car, Chris gave them one last chance, and after a couple of weeks the problem had been diagnosed to a worn out catalytic converter. However the cost to replace the exhaust system was horrendously expensive and Chris politely told them where they could stick their quote (we'll let you use your imagination).

This left Chris with a dilemma, where to take the car now, he chose Maztech of Melbourne to replace the exhaust. The stock system was replaced with a mild steel 3" into a twin 2 1/2" exhaust with 3" cat and twin mufflers. A week later, he was driving out of Maztech when the car decided that it would spit the dummy once again, this time breaking diff mounts. Would the problems ever end?

Once this was attended to, the car ran problem free for once, in fact the car ran so well that Chris ended up losing his license for 18 months. It was during this time, that he experienced a ride in a friends RX-3 Sedan using a 13B with a T04E hanging off it. This convinced him of one thing: he had to go with a turbo setup, strangely the naturally aspirated setup just couldn't compare to the rush of the turbocharged motor.

Over the next three months, Chris considered purchasing other turbo RX-7's including Series 3 models with conversions and the Series 5 model, however nothing could compare to the condition that his car was currently in. So rather than sell it, the decision was made to transplant a turbo motor into his car. After ringing several rotary workshops who told him he would be better off buying a turbo model or it would cost too much, he stumbled across Dyson Rotary in Geelong who told him that a rebuilt J-Spec Series 4 13B turbo motor could be installed in the car within two weeks. Needless to say, Chris eagerly dropped the car off.

Two weeks later, the car was ready and had been fitted with a Turbo model bonnet as well (they feature a bonnet scoop to feed the top-mount intercooler). The cars performance had improved out of sight, and with only a few weeks remaining till he regained his license, the rush was on to get the car registered and roadworthy. After a few minor problems were uncovered during initial inspections, Chris took the car back down to Dyson Rotary where it was discovered that the engine was sitting on the cross member (due to a Cosmo sump being fitted to the engine) and that new brakes were required. By now the number of problems encountered may have caused some to just sell the car to get rid of it, but Chris was determined to finish the car.

Over a couple of weeks, the car had its faults corrected (which also included repositioning the fuel pump) Chris made it to Vic Roads where after a bit of convincing and smooth talking, the car was finally deemed roadworthy and registered. After 18 months and numerous problems, Chris was able to finally cruise the 'seven' in time for summer. During this time, the 17-inch AMG Matrix wheels were added which as you can see match the cars paint extremely well, a series 5 RX-7 rear spoiler, lowered King Springs and heavy-duty Pedders shocks were also put onto the car, to further improve its ride and looks.

Inside the car, the modifications include a MicroTech handset, a AutoMeter Ultra Lite 30psi boost gauge and a custom gear knob, the standard seats are good enough, so why replace them? A decent stereo system is also fitted including a Sony Tuner and 10-stacker, Kicker 4" splits, Polk 6x9" and 6" speakers in the front and an Audio Strata amp.

Fast forward to late last year and whilst driving to Portsea the night before New Year's Eve, a Grey Kangaroo decided it would jump out of the nearby bushes and kamikaze itself into the RX-7, with little time to react, a collision between the two was inevitable. After getting the car to a stop (and possibly changing his underwear), Chris exited the car to find that the bonnet, bonnet scoop, lights and supports were all damaged, along with the front bar which had been pushed in. Upon further inspection, the intercooler had also gouged the hydraulic clutch hose, spilling clutch fluid all over the engine bay.

A few days later, the car was trailered back to Melbourne, where Scoresby Panels were given the job of respraying and repairing the car. Chris decided the original Mazda 5A Blue wasn't inline with the rest of the car and after several agonising weeks, Honda Captiva Metallic Blue Pearl was chosen as the new colour. Along with the respray, the guards were lipped, the rusted sunroof replaced and other exterior parts colour coded.

Since then there have been no further problems with the car, and Chris also recently competed in the MCCR/Maztech Dyno Day. After an initial period of wanting to sell the car, Chris saw the light and on the cards are a larger T04/66 hybrid turbo and larger front-mounted intercooler, along with all the other hardware upgrades that accompany these parts.

This is one T-REX that still has a few predators to hunt down...


Model: 1987 Mazda Series 4 RX-7 TII

Engine: 13B Twin Rotor Turbocharged

Engine Modifications: J-Spec rebuild, turbo porting, mandrel-bent 3inch exhaust with twin stainless mufflers, custom dump pipe from turbo, Turbosmart boost controller(10/18psi), Microtech MT8 Ignition & Timing Computer, HKS Super Blow-off valve, Simota Air Pod filter, VL Turbo fuel pump

Driveline: Standard Mazda 5 speed, 4.1:1 LSD differential

Performance: 171kw @ rear wheels on 10psi

Wheels & Tyres: AMG Matrix 17 x 8 inch, 225/45 tyres