Street Machine - - Contents -

Swing­ing for the fences with the turbo grey mo­tor that pow­ers Mark Riek’s su­perb FX ute

FOR those who didn’t catch our fea­ture on Mark Riek’s sen­sa­tional FX Holden ute in the June 2015 is­sue of Street

Ma­chine, we’ll run you through the high­lights. She’s a su­perbly re­stored old girl, pow­ered by what’s prob­a­bly the most high­tech Holden grey mo­tor in ex­is­tence – at least since the days of the Wag­gott twin cam and the like.

Built by Geoff Scott from Geoff’s Auto Stu­dio, it dis­places 2458cc (or a whisker un­der 150ci), with the bot­tom end con­sist­ing of a light­ened and mod­i­fied crank­shaft, a set of con­rods pinched from a Mit­subishi 4G64 four­cylin­der, and 81mm ACL pis­tons that would other­wise have ended up in a Mazda.

The camshaft is from Wag­gott, with .500in of lift and 232@50 du­ra­tion, and the head is the fac­tory grey cast­ing that’s been ported and fit­ted with over­sized valves and per­for­mance springs.

The in­duc­tion sys­tem is trick: a cus­tom in­let man­i­fold, an elec­tronic fuel in­jec­tion sys­tem pow­ered by a MOTEC M84 ECU, a PWR wa­ter-to-air in­ter­cooler, and – when we fea­tured the car – a Gar­rett T25 tur­bocharger.

It’s a mag­nif­i­cent con­coc­tion of parts that took plenty of R&D to per­fect, and with a tune by Rod Salmon at The Speed Shop in Gympie, Mark saw sev­eral thousand trou­ble-free miles with the ol’ grey mak­ing 141rwhp and 471lbft. That’s pretty im­pres­sive con­sid­er­ing a stan­dard 132.5ci grey mo­tor is rated at just 60hp at the fly­wheel.

Back then, Mark told us he had as­pi­ra­tions of fetch­ing 200rwhp out of the en­gine with fur­ther de­vel­op­ment, and when he snapped one of the dump pipe studs dur­ing a rou­tine span­nercheck, he got the ex­cuse he’d been look­ing for.

“I was go­ing to have to re­place the ex­haust hous­ing, and I’d been toy­ing with the idea of a big­ger turbo any­way,” Mark says. “It all kind of snow­balled from there.”

With the en­gine pulled from the car for some fur­ther de­vel­op­ment, we thought it was a great op­por­tu­nity to take a closer look at what is a truly unique pow­er­plant, and find out just how much power could be squeezed from a full­ef­fort grey.

The span­ner work and tun­ing were han­dled by The Speed Shop, and con­sisted of val­ve­train, fuel, ig­ni­tion and in­duc­tion sys­tem up­grades; a switch to se­quen­tial fuel in­jec­tion and E85; and a host of driv­e­line changes in the hope of sur­pass­ing Mark’s 200rwhp tar­get.

Due to the siamese in­take port con­fig­u­ra­tion, the fuel sys­tem ini­tially had just three in­jec­tors and the ECU was un­der the im­pres­sion that it was run­ning a three-cylin­der, two-cy­cle en­gine. The switch to se­quen­tial in­jec­tion meant a lot of changes.

“Ba­si­cally we were try­ing to get ev­ery­thing we could out of it,” Rod says. “We did some home­work and made a new al­loy in­take man­i­fold from scratch with a Plaz­ma­man 60mm throt­tle­body, be­cause to go to se­quen­tial in­jec­tion we had to run six in­jec­tors, and with only three in­take ports, that meant two in­jec­tors per port. We used 410cc in­jec­tors and we went to LS coils and an EFI Hard­ware bil­let dis­trib­u­tor to burn through that E85.”

Mak­ing the most of the switch to the high­e­roc­tane fuel, the turbo was up­graded to a Gar­rett GTX2863R with a dual ball-bear­ing bil­let tur­bine and a Tur­bosmart ac­tu­a­tor and boost con­troller reg­u­lat­ing boost to 17psi.

To with­stand the ex­tra pun­ish­ment, the val­ve­train was beefed up with Yella Terra rock­ers and Jet En­gi­neer­ing pushrods.

Hav­ing had vac­uum is­sues with the Tri­matic trans­mis­sion due to the turbo, Mark swapped it out for a man­u­alised Pow­er­glide with a cus­tom adapter plate and a 3800rpm TCE con­verter.

Once the car was back on the dyno, Mark and Rod were both stoked with the out­come. At 204rwhp and 17psi the in­jec­tors were maxed, mean­ing that there’s still more to be had from the old girl with up­graded squirters and more boost.

“In the­ory, the 410cc in­jec­tors we used should have been good enough to make 280rwhp, but they’re well and truly maxed at 204rwhp, so it’s drink­ing some fuel,” Rod says. “With that in mind, and the mas­sive amount of torque it makes, it’s prob­a­bly ca­pa­ble of more power than it’s show­ing on the dyno. Torque is up from 470lb-ft to 1100lb-ft, and while there’s been some gear­ing changes that would af­fect that, I’m com­fort­able say­ing that we’ve dou­bled the torque with the changes we’ve made, and it’s a com­pletely dif­fer­ent car to drive.”

Mark’s rapt, but he’s not all about dyno fig­ures; he’s got some ET ex­pec­ta­tions tied to this lat­est round of mods. “The goal is to beat Bob Hamil­ton's Cap­tain Ni­trous FJ, which ran a 12.98; that’s been the grey mo­tor record for ages.”

The car has only had two passes since the up­grades; a 13.247@99.52mph on 15psi, and a 13.201@99.88mph on 17psi, with the car run­ning out of revs in the big end and find­ing the 6000rpm lim­iter on both oc­ca­sions. Mark plans to bump the lim­iter up to 7000rpm, switch from 24-inch street tyres to a set of taller 26-inch ET Street ra­di­als, and is qui­etly con­fi­dent of a re­sult.

With bits from Yella Terra, Jet En­gi­neer­ing, Tur­bosmart and Plaz­ma­man to name a few, the en­gine has a lot of Aus­tralian-made parts, and that’s some­thing Mark did quite de­lib­er­ately. “I prob­a­bly paid a premium for it, but I tried to sup­port Aus­tralian brands where I could, be­cause I think they’re do­ing a great job and their parts re­ally are bet­ter”

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