When you’re deal­ing with gravel, the Speed­line Corse in 15x7 inches is a very com­mon wheel choice, here wrapped in Kumho rally rub­ber

NZ Performance Car - - News -

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.


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


The en­gine in an RX-8 is well set back from fac­tory, and that was some­thing the team didn’t want to mess with when adding another ro­tor. This meant cut­ting into the tun­nel to al­low the fit­ment of the longer 20B block

SUP­PORT STRUTS: Ex­ter­nal-reser­voir MCA coilovers BRAKES: AP Rac­ing four-pot calipers, AP Rac­ing ro­tors, hy­draulic hand­brake, OBP floor-mount pedal box EX­TRA: Chro­moly roll cage, Jap­speed ad­justable arms, ex­tended power bar, mod­i­fied tur­rets

IN­TE­RIOR SEATS: Re­caro STEER­ING WHEEL: OMP, wire­less con­troller IN­STRU­MEN­TA­TION: MoTeC EX­TRA: Lexan win­dow slid­ers, cus­tom car­bon in­te­rior mould­ings, flocked dash, heated wind­screen

EX­TE­RIOR PAINT: Gloss black by Bruce Rax­wor­thy Panel and Paint ENHANCEMENTS: Maz­da­trix car­bon roof, boot, wing, bon­net, doors; Spirit R side skirts, head­lights, guards

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