TRIPLE ROOSTER
When you’re dealing with gravel, the Speedline Corse in 15x7 inches is a very common wheel choice, here wrapped in Kumho rally rubber
When you’ve racked up four rally championship titles in your Group B RX-7, what’s the logical step forward? To slap an Al Marsh Rotorsport short-crank 20B peripheral-port (PP) into an RX-8, and get ready to roost your neighbourhood forest — Marcus van Klink proves why he’s the master of rotang-powered gravel-peelers.
FOUR CHAMPIONSHIPS DOWN, VAN KLINK WANTED A CHANGE. THE RESULT? A 20B RX-8 READY TO ROOST YOUR NEIGHBOURHOOD FOREST
Marcus van Klink has pedalled a ton of rally machines in the last 10 years — from Evo IIIs to Datsun 1200s. Any passionate rally fan will know that a few of them met their demise in high-speed unplanned off-road excursions, while others, like the Datsun, still reside in the van Klink workshop. But it’s his replica Group B RX-7 that you’re likely to know best, thanks to that high-pitched 10,000rpm 13B exhaust note echoing through the forest and its long list of rally wins that includes four national championships. It’s a regular on the gravel and a welcome sight at rallies all across New Zealand. But Marcus recently felt that it was time for a new challenge — time to wipe the slate clean and build something modern, something no one had seen before.
That’s not easy when you’re not going four-wheel-drive (4WD), and the only engine that interests you for the new project is a 20B peripheral port (PP). “I’ve tried the 4WD thing when I first started rallying and that ended in a few written-off Evos. I really enjoy the rear-wheel-drive stuff, and that’s what I’m known for,” he said. With that in mind, he started looking at chassis. The FD RX-7 was quickly ruled out due to its small size: “I had looked at an FD, but they are not much larger than the RX-7, and with the speeds we are doing you want some room around you.” The answer came in the form of the RX-8 chassis; but, with a bigger footprint, comes added weight — a total of 1378kg, to be precise.
When it came to building the car, Marcus knew just who to call, Palmside Automotive in Christchurch — he just hoped that the Ford Escort specialist would take less arm twisting than when it had built his RX-7. Again, the team was not sold on the project at first, but it wasn’t about to back down from the challenge.
Marcus has long used MCA suspension in his cars, and the RX-8 is no different, using a set of externalreservoir uprights. To get the longest possible stroke, the turrets have been raised 125mm up front, and have been replaced altogether in the rear
To gain extra travel, and volume in the MCA uprights, both the front and rear turrets were extended — in fact, the rears are actually Ford Escort items welded in place. Other changes to the chassis included modifying the back-seat area to accept the fuel tank and resetting the tunnel so that the engine position would remain factory despite the extra length from the third rotor. Brent from Palmside tells us that the chassis is very rigid from factory, due to the lack of a real B-pillar, so not much in the way of stiffening was required, as the roll cage is more than up to this task.
The other changes were made to the rear suspension. From factory, the RX-8 lacks any long forward-facing arms, so the power bar was lengthened and solid mounted, while all the other arms were replaced with adjustable Japspeed items. This should keep the tyre as square as possible — with too much negative camber gain, the inside of the tyre will wear too quickly, and you can’t just combat that with positive camber settings, as then you lose side bite. It’s a difficult balance to strike, but it’s something the team will continue to work on over the coming year.
With the kerb weight a concern, the call was made to Mazdatrix in the US — which produces a vast catalogue of lightweight carbon components for the RX-8. The boot, roof, bonnet, wing, and doors were ordered, while the other external additions were kept factory with Spirit R components. Along with the removal of any glass, this has brought the weight down to around 1300kg, even after adding in the extra rotor and all the tools and spares a rally car carries, which means it’s only 100kg heavier than the old car.
Marcus is well versed in the art of pedalling a 13B PP in the gravel stages of Rally New Zealand, but, this time, he wanted a little more under his foot, and got talking to Al Marsh Rotorsport about running a 20B — one with the kind of unmistakable sound that will leave any crowd weak at the knees when Marcus buzzes past. Though the RX-8 will probably make in excess of its current 275kW, all-out power was never a concern with the short-crank 20B; it was reliability Marcus had in mind: “Roughly 300hp [224kW] is the max you can put down in a rear-wheel-drive car on gravel. Anything more, and it’s just spinning the tyres. With this car, you can’t keep revving it like the 13B; you need to short-shift to keep it from just spinning. Even then tyre wear is going to be excessive.”
The engine is based on a short-crank 20B using S5 RX-7 naturally aspirated (NA) rotors, Mazda Factory Race (MFR) bearings, PP housings, and an MFR dry sump. Built and tuned at Al Marsh Rotorsport, it should provide that reliability Marcus has been looking for. And, as it’s backed by a Quaife 69G six-speed, plucking those gears has never been easier.
The remaining underpinnings are rather simple but there have been geometry compromises. A live axle would offer endless droop, while the independent rear suspension (IRS) limits this in a big way. RX-8 rally-specific parts are just not made, and, in fact, the rear adjustable arms are of a type traditionally found in a drift car. Despite small limitations like this, the car has shown great potential in gravel and tarmac trim. In fact, on debut at Targa New Zealand 2016, Marcus said that he never saw the service vehicle: “We were all working towards entering the RX-8 in the 2016 Targa, having finished just a couple of days before with next-to-no testing. We arrived ready to go, and, on our way to the first stage, we went past our new service vehicle, which just stopped while driving to the first service. Never saw the service vehicle again the whole event, as it was stranded in Taupo, unable to be fixed. Unbelievable to think [that] after all that hard work by everyone involved, our piston-powered van was the most mechanical drama we had.”
This season, expect the RX-8 to hit rallies all across New Zealand as the team takes on the rear-wheel-drive open-class champs, aiming for a top-10 overall finish each round. But Marcus makes no promises, as the car will take some dialling in with this chassis and engine combo. In the meantime, all lovers of the old RX-7 need not worry; it will be out and about to a select few classic events.
You will find no big bodykits here; the RX-8 runs Spirit R guards, side skirts, and headlights, while just about every other panel, including the roof, has been replaced with carbon-fibre items imported from the US