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One step ahead: 1969 Plymouth Road Runner

28 June 2015


Ever since the Japanese performance vehicles of his youth, Johnny Burkhart’s cars have been a step ahead of the game — his 1969 Plymouth Road Runner is nothing less

Johnny Burkhart knows his way around cars. That much is evident, even upon the first glance of his spectacular Plymouth Road Runner. But the path Johnny took to get to this fine machine is not the one you may expect. You see, Johnny’s Plymouth is one step ahead of the game because that’s how most of his cars have been, ever since he started playing around with the Japanese muscle of his youth — the majority of which were show-quality, rotary-powered Mazdas. 

In Masterton during the early to mid 2000s, Johnny was cutting his teeth on big-power Japanese streeters, and the little rotary was his engine of choice. He has owned and built his fair share of old school Mazda RX coupes and sedans, covering most rotary bases with turbocharged and naturally aspirated engines. From bridge ports, through to top-dog peripheral port engines — and always finished the vehicles to a standard that pushed his contemporaries to up their game.

After building a large number of varied cars, Johnny began to think seriously about building himself his dream car — a 1969 Plymouth Road Runner. However, due to the cost and time involved in such a build, he knew that, realistically, it was out of reach for a while.

Then, one day, life threw him an opportunity to purchase and import a very tidy example — right as he was in the midst of building a new house, getting married, buying another business, and had another baby on the way! Johnny’s wife, Dani, is clearly very understanding and supportive of his automotive endeavours, as, before long, the Road Runner was on its way to the Burkhart residence. 

Despite his history with tiny rotary engines, Johnny’s main love is big horsepower (obviously), big boost (obviously), and even bigger cubes. He decided to undertake a full bare-metal rebuild, with a Hemi under the bonnet and with his love for boost hinting at the induction system. Before the build started, Johnny spent a lot of time on the phone and the internet researching the best Hemi builders. Due to both his reputation and the favourable exchange rate, Tim Banning at For Hemis Only (FHO) in Canada was selected to build the engine. 

That engine is a truly impressive work of art, incorporating a whole parts store worth of top-shelf, brand-name parts. The World Products alloy block is filled with an Ohio forged crankshaft, Oliver steel rods, and CP forged pistons — the 4.506-inch bore and 4.300-inch stroke yield an enormous displacement of 550ci — with a boost-friendly compression ratio of 9.0:1. The breathing is handled via a solid roller camshaft and a very serious valvetrain assembly courtesy of the Comp Cams, Ferrea, Manton, and Stage V catalogues. 

Of course, cubes were never going to be the only way the engine made its power — a giant F2 ProCharger was installed, forcing copious quantities of pressurized air through stainless piping, into a PWR intercooler, and on to the custom-fabricated intake manifold. Being from the new school, Johnny wasn’t planning to mess around with blow-through carburettors, either.

The big Hemi runs a top of the line fuel injection system, comprising FAST 92mm throttle body, an octuplet of Bosch Indy Blue 160lb injectors, custom fuel rails, and FAST XFI 2.0 fuel injection. A behemoth exhaust system comprising TTI headers with huge 2¼-inch primary pipes, twin 3½-inch exhaust pipes, and matching Flowmasters refines the unearthly rumble that nine litres of Hemi is capable of producing. Johnny can also turn the volume up to 11 at the flick of a switch if the need arises, thanks to the Quick Time electronic exhaust cut-outs — if you’re in the lower North Island and want to make a quick buck, start importing earmuffs and hearing aids!

With the four-digit power output — not to mention earth-shifting torque levels — that Johnny was aiming for, the all-too-familiar story of beefing up the remainder of the car to cope began. The first weak link was eliminated with a BTE Powerglide, and a parts list that a drag racer would kill for. Reid SFI-approved transmission case, 1.80:1 ratio straight-cut 9310 gears, billet valve body, Top Dragster transbrake, and a high gear 10-inch clutch pack combine into a bulletproof transmission that should harness the Hemi’s phenomenal torque without any issues. Likewise, the diff is a super tough Strange Dana 60 item with 40-spline axles, fed by a huge 3½-inch chromoly driveshaft — she’s not blowing up anytime soon. 

Although it’s a bit of a Kiwi tradition to spend all our money on a big-power engine, leaving no money to tidy up the rest of the vehicle, Johnny’s modus operandi is a bit more thorough. The vehicle needed to be as well presented as possible both inside and out. Countless hours were spent stripping the body and building the roll cage, and his good friend Kurt worked on the tubs that were planned to house the large rear rims. The car was fully stripped, blasted, and epoxied, in preparation for its new coat: an updated shade of the classic Hemi Orange. Part of the reason Johnny was able to achieve such a result, in terms of making the huge-power engine cohesive with the cruiser-style car, was by undertaking as much of the work as possible himself. 

“I imported nearly everything needed for the car, and it’s been built by me with some world-class local Masterton help on a budget,” Johnny says. 

For example, all the bodywork was done by Johnny’s mates Kurt and Shane, with the use of mate Spider’s spray booth, with Johnny helping out where he could.


The presentation extends to the chassis, where Johnny fabricated the C-notched rear chassis rails, as well as numerous strengthening modifications, including; chromoly chassis connectors, seam welding, and bracing to the rear chassis rails. New Magnum Force front and rear ends were also installed, bringing the Road Runner’s ride and handling into the modern era. The tubular chromoly front K-member allows for fully independent front suspension, doing away with the Mopar’s antiquated torsion bar system, just as the Magnum Force four-link rear end replaces the leaf springs.

The thoroughly modern suspension also allows the Road Runner to sit comfortably low over its Ridetech ShockWave airbag suspension, and the Magnum Force K-member’s quick ratio rack and pinion steering ensures the Hemi’s torque will be hard-pressed to catch Johnny slipping. 

The final piece in the mechanical package comes in the form of Wilwood’s finest, with massive six-piston front and four-piston rear calipers, and equally enormous 14- and 11-inch cross-drilled and slotted rotors. Johnny’s original wheels of choice were a set of deeply dished 22-inch rollers, but the combination of liquorice-strip tyres and quad-digit horsepower gave him what could euphemistically be called a traction problem. Needless to say, he soon made the move to rubber better suited to such a torque monster. Thin, 17×4-inch Weld Racing wheels proudly display the big Wilwoods up front, while at the rear, 15×10-inch Billet Specialties double-beadlocked rims and fat Hoosier rubber don’t just look the part, but also makes a fair fist of transferring well over 1000hp to the tarmac. 

With the Road Runner coming together, the hours that Johnny and his mates poured into the bodywork paid off, with a stunning custom PPG three-layer pearl, based on Hemi Orange, applied flawlessly by Shane Lovell. For a four digit producing car, it’s actually very subtle — with only the fat rear rubber, tiny ‘ProCharged Hemi’ bonnet scoop decal, and 1600HP number plate giving the game away. This subtlety is carried over to the interior, where you won’t find big bucket seats, a sheet-metal dashboard interior, or lurid roll-cage padding. Instead, a swathe of Auto Meter carbon-face gauges keeps Johnny in sync with the big Hemi, and the family is kept comfortable by the stock bench seats, plush new carpet, and Sony entertainment system — remember, this is first and foremost a family car. 

With the car being finished just before Beach Hop 2014, it would have been a miracle not to encounter teething problems, even in a build as thorough as this. These gremlins showed up at Whangamata, and saw Johnny take a day out of his Beach Hop calendar to trailer the Road Runner to Carl at C&M Performance to be sorted out. Thankfully, the problems were nothing beyond Carl’s ability, and the Road Runner was soon back in the Whangamata sunshine. As a testament to how reliable and streetable the big Hemi is, the Road Runner is not often seen without a child seat inside, and that includes events like Beach Hop and the recent Cruise Martinborough festival.

“It’s been a fun and rewarding process, with its fair share of blood, sweat, and tears!” says Johnny of the build, “but now that it’s done, we are enjoying it and getting lots of family time and holidays in it. With some boosted Hemi power, it is an absolute beast, but still street driven.” 

Don’t worry, we haven’t forgotten the million-dollar question: how much power does 550ci of procharged Hemi get you? Well, so far,  the Road Runner’s been on the dyno for a low boost pull, which netted it 1300hp at the flexplate, or around 1000hp at the wheels. Yeah, we all know the number plate says “1600HP”, but don’t worry — Johnny’s just getting started, and has expressed a desire to run nine-second quarter miles, which should be a walk in the park for the big Hemi. When Johnny says it’s making 1300hp on low boost, and that a big power tune running high boost and E85 is coming, you’d best believe him — it’s a special kind of person who can, quite seriously, say that 1300hp is low power. 

Johnny’s Road Runner was featured in NZV8 Issue No. 120 (May 2015). You can grab a copy here.

Johnny Burkhart: 1969 Plymouth Road Runner

  • Engine: 550ci Hemi, World alloy block, custom CP forged pistons, 9.0:1 compression, Ohio forged crankshaft, Oliver steel race rods, Comp Cams custom solid roller camshaft, Manton custom pushrods, Comp Cams double valve springs, Comp Cams retainers, Ferrea titanium intake valves, Ferrea inconel exhaust valves, Stage V 1.6:1 ratio roller rockers, bronze valve guides, Stage V alloy heads, CNC ported, Cometic gaskets, 2¼-inch TTI headers, 3½-inch exhaust, Quick Time electronic cut-outs, 3½-inch Flowmaster mufflers, custom PWR alloy radiator, Milodon external oil pump, low-profile sump, custom oil pickup, custom intake manifold, custom fuel rails, Bosch Indy Blue 160lb injectors, FAST 92mm throttle body, F2 Procharger, PWR custom intercooler, custom stainless piping, custom 100-litre alloy drop tank, Milodon fuel pump, Aeromotive fuel pump controller, Aeromotive fuel pressure regulator, braided fuel lines, FAST XFI 2.0 fuel injection, MSD Digital-7 ignition, MSD Pro Billet distributor, aluminium engine mount plate
  • Driveline: BTE Powerglide, 2500rpm stall converter, Reid SFI cases, roller tail housing, 1.80 straight-cut 9310 gears, billet valve body, Top Dragster transbrake, billet two-ring servo, wide kevlar racing band, 10-inch clutch high gear pack, Strange Dana 60 diff, 40-spline axles, 3½-inch chromoly driveshaft, Strange 1350 universal joints and yokes
  • Suspension: Magnum Force chromoly K-member, chromoly control arms, custom tubular splined sway bar, Ridetech HQ-series ShockWave air suspension, Magnum Force four-link rear, Pro9 chromoly trailing arms, custom diagonal link, quick ratio rack and pinion steering
  • Brakes: Wilwood master cylinder, Wilwood bias valve, 14-inch cross-drilled and slotted rotors (front), Wilwood six-piston calipers (front), Wilwood 11-inch cross drilled and slotted rotors (rear), Wilwood four-piston calipers (rear)
  • Wheels/Tyres: 17×4-inch Weld Racing billet front runners, 15×10-inch Billet Specialties double beadlock (rear), Phoenix 17×6 drag tyres (front), Hoosier 29½x14½x15 (rear)
  • Exterior: Custom tubs, PPG paint (Hemi Orange based)
  • Chassis: Chromoly chassis connectors, custom C-notched rear rails, custom bracing
  • Interior: Factory bench seat, factory steering wheel, Auto Meter carbon gauges, six-point owner-built roll cage, raised driveshaft tunnel, new carpet, TCI shifter, Sony DVD, Sony speakers
  • Performance: 1300hp (low boost, on pump gas, and with full exhaust); big power tune, with high boost and E85, to come!