10,000 REA­SONS

HYPO HEAD-SWAPPED MIVEC MI­RAGE

NZ Performance Car - - Contents - WORDS: MAR­CUS GIB­SON PHO­TOS: DUN­CAN ROURKE

It would seem that true pi­o­neers within the car world are few and far be­tween these days. For the most part, what’s be­ing cre­ated is not ground­break­ing; it’s sim­ply build­ing on what some­one be­fore laboured over. It takes a brave soul to ac­tu­ally step off that proven path and forge their own trail — es­pe­cially when it’s so easy to go the known route and you’ve had a spec­tac­u­lar fail­ure that saw two rods ex­it­ing the block at around 10,000rpm on your first at­tempt. To then come back from that, pick up the pieces, and start all over again — well, that right there must take some se­ri­ous down­stairs hard­ware to want to risk it all over again.

While at first glance this Mi­rage might not seem like some­thing out of the norm, pop­ping the bon­net will re­sult in head-scratch­ing, as quadru­ple Jen­vey throt­tle bod­ies punch you in the face where you’d ex­pect a big old snail to be. To re­cap, it’s not the first time that we’ve seen Cameron McEl­roy’s ’96 MIVEC Mi­rage be­fore; in fact, we were there the day that the rods ejecto-seato’d out the bot­tom of the block at the 2010 Honda Mega Meet, as we had just shot it for a fea­ture in Is­sue No. 171. Hypo nat­u­rally as­pi­rated (NA) Mit­sis just aren’t the norm, so, as you can imag­ine, it was grab­bing its fair share of at­ten­tion from the rev-happy Honda crowd that day. It had not been a short road to get to that point for Cam, so it was a big kick in the afore­men­tioned hard­ware for the first out­ing to end the way it did.

Fea­tur­ing a cus­tom 5.1-ra­tio fi­nal drive, the gear­box is a trick unit run­ning a ’98 RS gear set, ’98 RS shifter ca­bles, and a short shifter. The diff is a Cusco 1.5-way lim­ited-slip

Be­ing an RS, the Mi­rage is de­void of any crea­ture com­forts — but who needs those when you’re strapped into a Bride Gardis III, chas­ing that next apex?

Cus­tom car­bon guards were pro­duced to house the 225 Hankook semis come race time, when the 15-inch TE37s are bolted on

“I was pretty anti NA for a while af­ter that,” he says. “It had cost a lot of money to build that en­gine, and, af­ter only 3000km, it went bang. I con­tem­plated putting an Evo mo­tor in — I had good con­tacts at Mitsi New Zealand at the time and got of­fered an Evo X en­gine — I thought pretty long and hard about it and al­most did, but the front-wheel-drive gear­box was go­ing to be an is­sue, and still, to this day, I be­lieve that not re­ally any­one has done an NA MIVEC prop­erly.”

Spurred on by the be­liev­ers in sup­port of what he was try­ing to achieve, Cam re­fused to quit, and a new plan was hatched for what he calls a “sim­pler” com­bi­na­tion. For­go­ing the pre­vi­ous short-stroke hy­brid 1600/1800 combo, this new pack­age would uti­lize a later model 1800cc 4G93 turbo block re­tain­ing the fac­tory stroke and bore, with a MIVEC head on top. Sim­ple, right? Well, the fact that the head nor­mally lies in the op­po­site di­rec­tion is where the trick­ery that con­sumed Cameron for a good num­ber of years lies. “If some­one men­tions a head flip on a B-Se­ries Honda, you’d in­stantly think he’s a mad­man,” says Cam. And while you’d prob­a­bly also be quick to class Cam as one too, he had an ace up his sleeve, given that, in ’96, Mitsi swapped all its en­gines, ex­clud­ing the V6s, from the left side of the bay to the right, mean­ing that a pre-’96 MIVEC head, when flipped, would bolt di­rectly to the later model 1800 turbo 4G93 block without too much has­sle. The has­sle would lie in get­ting it to func­tion: “Ev­ery­thing was a night­mare in­ter­nally.”

This work be­gan with a set of cus­tom cams, as they are dif­fer­ent lengths due to the in­ter­nal MIVEC so­le­noid. The oil feeds that ac­ti­vate the MIVEC also had to be mod­i­fied to en­ter the op­po­site end of the shaft. The later model trig­ger sys­tem had to do a com­plete 180. The list of re­quired mod­i­fi­ca­tions just goes on and on, to the point that noth­ing on, or in, the mo­tor is fac­tory. Talk about a com­mit­ment to mak­ing it hap­pen! Not all the work was sim­ply to get it func­tion­ing, though; per­for­mance was also a fo­cus. The head was heav­ily ported and the valve seats re­shaped in prepa­ra­tion for a rev-happy valve train, while the block in­ter­nals were re­placed with cus­tom forged parts to create a com­bus­tion­mix-crush­ing 12.5:1 comp. Was all the ef­fort worth it? We’d say hell yes, as the power fig­ures of 165kW and 203Nm would make an equiv­a­lent Honda B-Se­ries run and hide for cover.

With a rev limit cur­rently sit­ting at 10,000rpm, that in it­self cre­ated a unique prob­lem with res­o­nance. “It’s a very, very ag­gres­sive mo­tor,” Cam tells us. “I couldn’t keep any­thing on it. I orig­i­nally had a light­weight crank pul­ley on it, and I’d do a track day and be miss­ing a bunch of bolts and stuff would be bro­ken or cracked [at the end]. Alis­tair from Mac­bilt En­gi­neer­ing told me to put a fac­tory crank pul­ley back on, which re­moved the res­o­nance.” Even the in­take man­i­fold suf­fered, split­ting al­most en­tirely in half due to the vi­bra­tion. Seiz­ing the op­por­tu­nity, a new set of Jen­vey quads re­placed the 4GAE items, with Alis­tar putting to­gether a new man­i­fold. Alis­tair’s sig­na­ture can be found all over the Mi­rage — from the eight-point roll cage to the cus­tom head­ers — and he is some­one who Cam cred­its with get­ting the car to work as well as it does.

The forged ro­tat­ing assem­bly is topped off with cus­tom 12.5:1-com­pres­sion JE pis­tons that have been Te­flon and ce­ramic coated. The crank it­self was knife edged be­fore be­ing ni­trided, while the rods are Argo items The only off-the-shelf Mi­rage-spe­cific per­for­mance part on the build is the Monster Sport car­bon bon­net

The head is a se­ri­ously trick piece of kit, with cus­tom cams, JUN valve springs, ti­ta­nium in­take valves, sodium-filled ex­haust valves, and ti­ta­nium re­tain­ers. The valve seats have been shaped and a heavy dose of port­ing has taken place Although still reg­is­tered and war­ranted, the Mi­rage sees very lit­tle street run­ning these days The hy­brid mo­tor combo has been dubbed a ‘4G9X’. The head’s from an early MIVEC 1600, while the block is a later model 1800 turbo unit. This made re­vers­ing eas­ier, as the head bolted di­rectly on, but that was where the easy stopped. Ex­ten­sive cus­tom work en­sued to get the com­bi­na­tion work­ing, leav­ing no fac­tory parts to be found

Which was no easy feat given the cus­tom na­ture of the build. Off-the-shelf up­grades just don’t ex­ist, although many parts meant for the Mi­rage’s boosted big brother, the Evo, were able to be re­pur­posed — parts like the Race­fab World Rally Cham­pi­onship (WRC)–style cross mem­bers, tubu­lar arms, and Evo VI sus­pen­sion. It’s all the stuff that you sim­ply can’t see at a glance but which makes for proper race car un­der­pin­nings in a ve­hi­cle that weighs only 910kg wet. Given that there is very lim­ited power on of­fer, Cam had to be pedan­tic about weight. Any­thing that went in had to come out else­where. The fact that it tipped the scales at 1040kg in fac­tory trim and now has a 70kg eight-point cage yet still comes in 130kg lighter than fac­tory should be a good in­di­ca­tion of just how far this has been taken. But be­ing so light also means that Cam needs to bring his A-game come track time. “It’s so light in the rear [that] you just don’t get away with any­thing,” he says.

With some more con­sis­tent time on track, he should be able to re­ally dial his times and show the true po­ten­tial of the lat­est con­fig­u­ra­tion. But dreams of run­ning the car com­pet­i­tively, which were the fo­cus in those early days, at least for now have taken a back seat to track days at his lo­cal, Man­feild Cir­cuit. How­ever, that hasn’t stopped Cam from dream­ing up the next round of up­grades, fo­cused on ex­tract­ing some se­ri­ous power from the 1800 and spurred on by what guys run­ning in the World Time At­tack Chal­lenge are do­ing with su­per­charg­ers and K24s, mak­ing up­wards of 450kW. Given the en­gine’s new lay­out and its forged in­ter­nals, this would not be a hard task at all to make work. But, for now, Cam will be more than con­tent to stalk some Hon­das out there on track and con­tinue to have peo­ple scratch­ing their heads any time the car­bon bon­net is popped on this world­first com­bi­na­tion.

Newspapers in English

Newspapers from New Zealand

© PressReader. All rights reserved.