Front wheels scrabble for grip as the RunX RSi’s speed rises, the revs never dipping below 6 000, and a swift, instinctive nudge of the sequential gear-shift calling up the next ratio each time the graphic-display tacho kisses the eight-five mark. The car bucks a fraction as it crests a ridge, the revs rising as air separates the tyres from terra firma. It lands stable, and with no loss of momentum.
A tight little downhill right/left with a gateway on the exit looms. Go in deep – v-e-r-y deep – stand on the brakes, quickfire downshifts, point the nose inside the first apex, tug the handbrake.
The tail steps out and the car goes sideways. Use the power to pull you straight before getting the tail to flick out in the opposite direction. More power and blast between the posts and on towards the riverbed…
It all happens far, far quicker that you can say or read it, and to witness the reality never ceases to amaze: man’s faith in a machine, and the machine’s ability to cope. With just two litres, two-wheel drive and a not outlandish level of modification, a Class A8 (the top category) SA national cham-pionship rally car is capable of challenging a number of rules of physics – in the right hands, of course. And in its first season, a RunX RSi captured yet another manufacturer’s championship for Toyota, and provided the company’s seasoned, but still fiercely competitive, front man Serge Damseaux with his ninth driver’s crown. Clearly, then, the team is on top of its game.
In 2002, it tackled the National Rally Championship with a previous generation Toyota Corolla RSi. For 2003, it was a choice between the new Corolla or the RunX hatchback, and the decision went to the more youthful model. Either way, it meant starting from scratch, although some aspects of the previous Corolla could be fairly readily applied to the five-door. The challenge was to improve upon the old car’s competitive yet forgiving nature, a not so straightforward task…
The first obstacle is size. Yes, the RunX is obviously shorter – by 140 mm – and is 5 mm wider, but it is significantly taller: 85 mm is a lot when you are looking for a low centre of gravity. A 135 mm longer wheelbase is some consolation (“It’s just about right”, says Damseaux), but that tall body does present a handicap, and partly explains why co-driver Bob Paisley sits so low and slightly behind the driver. Also contributing to the need to concentrate as much mass as possible within the wheelbase is the motor, which is canted back and mounted low in the engine bay.
Weight is another critical factor, and the RunX does not fare too badly in this area. The regulations dictate that the car should weigh no less than 1 055 kg “dry” (ie, no fuel, no spare wheel or any other loose equipment), and the RSi tips the scales at 1 102 kg which, incidentally, is only about 30 kg less than an RSi road car in the same condition. Look around the stripped out cockpit, note the use of carbon fibre for such items as the door panels, the Corbeau carbon/kevlar seats, and you wonder why the difference is so small. Well, a rally car has to be strongly built, and without the use of expensive exotic materials, adding strength generally means adding weight. The roll cage contributes 30-35 kg, along with an on-board fire extinguisher system, and beefed-up running gear fitted to what is already a strengthened bodyshell. Getting down to that minimum weight will take far more than a mail order “get slim quick” programme…
As stated at the beginning, getting power – nearly 200 kW of it – transmitted to a loose surface through just a pair of steered wheels takes some engineering ingenuity. Traction can only take place where there is contact, so the holy grail of suspension designers is keeping the wheels on the ground as much as possible. On paper, the RunX’s MacPherson strut, lower A-arm front suspension appears to be run-of-the-mill, but there is a lot more to it. Regulations permit the mounting points to be moved within a radius of 20 mm from the standard production car’s, so the geometry cannot deviate too much, but camber, roll centre, anti-dive etc can be altered with the strut’s positioning.
The top of the strut is mounted in a spherical bearing in a machined mounting plate that permits camber adjustment. The strut tube is bolted to the machined billet aluminium upright, the bottom of which sits in a spherical bearing in the A-arm.
This consists of a fabricated and machined lateral arm rose-jointed to a crossmember, and a machined and fabricated pushrod bolted to the lateral arm (to form the “A”), with the rear of the pushrod located by a bracket to the floorpan. The lateral arm controls lateral movement relative to the car, and the pushrod the longitudinal movement. The hubs are from a Corolla WRC car.
It is no less imaginative at the back. The regs allow for the standard torsion beam axle to be dispensed with, providing original mounting points are utilised, but the RSi features a unique fabricated axle made from chrome-molybdenum tube. A thick, non-rotating centre tube is fixed to the underfloor in the standard position, with the trailing arms rotating around the tube on needle roller bearings. In effect, the layout is an independent torsion beam axle similar to that of an early BMW 5 Series, except the Five had the luxury of a centrally mounted bush that the RSi cannot use because it is not a standard mounting.
To obtain maximum benefit from these revised layouts, Proflex competition dampers from Holland are used, which provide extremely low friction/stiction and are adjustable for high and low speed bump damping as well as rebound. Shim stacks are used to create the basic damping forces, then adjusters on the damper body are tweaked to fine-tune the settings to suit the road conditions.
An anti-roll bar is fitted at the back, but not at the front. The front suspension has to be supple enough to allow the wheels to independently follow and, importantly, remain in contact with, the surface’s contours while transmitting motive power. Tyres – 205/65 Dunlop SP Sport 85-R F51s mounted on 15×7-inch alloys – are super grippy, but the fronts lose their effectiveness after 20 kilometres or so of special stage…
Not surprising, really, if you consider that the accelerator pedal is to the metal most of the time. The engine is a square (ie, identical bore and stroke) Toyota 3S-GE 2,0-litre 16-valve twin cam with a four-trumpet inlet manifold and eight injectors operated via a throttle slide controlled by a Motec fully programmable electronic injection system. With a 12,5:1 compression ratio and running 102 octane racing fuel, it pumps out a whopping 195 kW at 8 200 r/min (97,5 kW/litre!), and produces 240 N.m of torque at 6 800. A fabricated radiator with a Land Cruiser aluminium core looks after engine coolant, and a water-to-oil heat exchanger prevents the Castrol lubricant from boiling.
The bellhousing and flywheel are manufactured in-house, and a Sachs twin-plate sintered clutch is used. Transmission is a Hewland PTC six-speed sequential ‘box with changeable ratios driving through an eight-plate limited slip differential, Hewland driveshafts and CV joints.
And the performance lives up to expectations – with a surprise or two. The tyres do not break traction easily, and first gear is l-o-n-g, so getting off the mark on tar is a delicate balancing act. Nevertheless, the RSi got to 100 km/h in 6,14 seconds, and reached the kilometre marker in a remarkable 25,79 seconds in top gear at a nigh-on top speed of 202 km/h, indicative of the close, but low, gearing necessary for rallying. At 8 800 r/min, the limiter kicked in with the computer showing 205 km/h. Fuel consumption? Rather not ask, but anything between 1,3 and two kilometres from each of the 50 litres in the foam-filled tank…
In its natural habitat – on gravel roads – there is little discernible difference in the RSi’s acceleration. In fact, it feels quicker because the bombardment of stones on the underside adds to the already raucous mecha-nical din (105 dB at 120 km/h!) that adds to the sensation of speed. It is a full-on aural assault. And it is here, on a rally stage, with the scenery whipping by in a blur, that you finally get to wonder at those laws of physics.
With less suspension travel than the old Corolla, over rough stuff the RunX is livelier at the back but without upsetting the overall balance too much. A five-point Willans harness lashes your body to the firm seat, yet the ride is relatively supple: there are road cars that jar your kidneys more than this. You can hear wheelspin taking place over patches of softer ground, but the RSi tracks where you point it with reassuring poise. The hydraulic steering is a WRC system with just two turns from lock to lock, and the power assistance takes much of the strain away from the relentless feedback from the road wheels as they fight for dominance over the surface.
And when it comes to stopping, giant Alcon discs – ventilated at front with four-piston calipers, solid at back with two-pot calipers – scrub off speed dramatically and with amazing efficiency, yet without ABS. There are twin master cylinders, and the front/rear balance can be adjusted: effectiveness is then a matter of right-foot sensitivity.
