What could be tougher than a ’66 Pontiac GTO running 8-second quarter miles? Not much, if you ask us.

You know you’re onto a winner when your wife calls you to see if you want a drag-spec 490ci big block Chev engine. However unlikely that may sound, that’s exactly what happened to Michael Franklin. It was, he says, “The start of the never-ending empty wallet.”

At the time Michael had a pretty tough street-spec HQ ute, into which the 490 was dropped. With the big block in place the ute was running easy high 10-second quarters. Add a 300hp shot of nitrous oxide and the time card read 9.90. All was good and well with the ute until Michael’s brother-in-law, Darren Saunders (a familiar name on these pages), offered him a 540ci engine built by Huntsville Race Engines USA.  With the bigger motor in place the ute ran 10.0 naturally aspirated, and slid its way to 9.3 on the bottle. The problem was, with the ute still being relatively small-tyred, those nine-second quarters were run using both sides of the drag strip, and with some white knuckles on the steering wheel.

Package Deal

The Huntsville engine had arrived in New Zealand to go into the ’69 Chev Camaro that graced NZV8’s cover back in December 2006 (issue 19). Not long after the Camaro’s appearance in the magazine, it was sold to Darren Saunders. Darren already had a similar engine in his second generation Camaro, so the Huntsville was up for grabs, with Michael the first person in line.

The big motor is based on a Dart Big M block, and is fitted with all sorts of fruit such as a Callies crank, Manley H-beam rods and JE pistons. Dart also supplied the heads and intake manifold, to which a 1090cfm King Demon carb is now fitted.

While good for a decent power figure in naturally aspirated form, the engine is even better once the 300hp Zex nitrous oxide system is fired into life. The beauty of the nitrous is that the engine is very relaxed without the bottle turned on, so much so that it can handle street use.

Big Tyres Needed

Like many muscle car fans, Michael had always wanted a tubbed car, and thanks to the monster motor now in his possession it became more a case of need than want.

When searching Trade Me for a suitable car, Michael fell in love with the 1966 GTO. Although it was rougher than he had hoped for, he bit the bullet and made the purchase. The car already had a ladder bar rear end, big tubs, and came with the 15×4- and 15×15-inch Weld racing Drag Light rims, as well as QA1 coil-over rear shocks and Koni fronts. The rear half of the stock chassis had been replaced with a Mark Williams item and, thankfully, it looked as if the installation had been done properly.

However, the exterior didn’t quite measure up. “I didn’t like the colour or the bonnet, and the back guards were a mess”, Michael says. “The boot weighed 42.5 kilograms and the diff gears were stuffed. I got hold of Shane from Segedins and asked him to bring me down a bonnet with a 4.5-inch cowl and a lightweight boot lid, then set about stripping the body down. OPG (Original Parts Group) in the States was very helpful with sorting new rear quarters, door rubbers, hood lining, front lights and some chrome mouldings. It had just about anything you could think of for a 1966 GTO.

With the parts landed, Michael set about fitting them and painting the car himself which, considering the size of it, is no small task.  While the car was in bits, more roll cage was added
and the boot lid was modified to be hinged rather than clip-off.

Just Add Motor

Before the motor was dropped in the hole, the lads at Auto Trans built up a turbo 400 that would handle the torque of the big block and a bigger shot of nitrous when required.

Because the motor was professionally built in the US and had done little before landing in Michael’s hands, it could be easily dropped in. A set of Hooker super comp headers was added, as was an MSD Digital-7 Plus ignition system; apart from that it remained as Huntsville Race Engines built it.

He may be a dab hand with a welder and a spray gun, but Michael quickly learned that wiring wasn’t his area of expertise.

After taking the car to Magnum Motors for its initial fire-up, all seemed well. However, it wouldn’t rev above 6800rpm. After plenty of head scratching, Carl Jensen from C&M Performance rewired it and got the problem sussed. With everything running as it should, the dyno was spun to the tune of 872hp at the tyres, an impressive figure in anyone’s book.

Before the fix the car ran consistent 9.1-second passes at 142mph. While Michael was understandably upset about not breaking the eight-second barrier, a nine-second pass for a big and heavy car is nothing to sneeze at.

The fix was sorted just before the Century Battery Nationals last year. All was looking well until it rained. The lads, now with time on their hands, ended up sitting at home on the rainy day, and decided to pull the filter off and check the engine’s health. It was lucky the car didn’t race that day after all — metal filings in an engine are never a good sign. A rebuild was on the cards.

Magnum Motors stripped and rebuilt the motor without the unwanted metal inside. After the rebuild it was back on the dyno where it punched out 878hp, aided by a few secret additions from the Magnum crew.

To date the car’s best quarter mile is an 8.90 at 149mph, and Michael reckons there’s plenty more to come — once his wallet refills. When that happens the car will also become street legal.

Street-Bound Strip Weapon

The 5000rpm stall converter and 4.56:1 diff ratio may not be the most friendly for the street, but the reality is that the car won’t be seeing huge street miles. Since brother-in-law Darren’s Camaro has essentially the same engine set-up and sees a bit of street time,  Michael is aiming to do the same.

I’m sure I’m not alone in thinking that the two eight-second, big block, nitrous-fed cars cruising the streets together would be an impressive sight.

Michael Franklin – Owner Profile

Age: Who cares?
Occupation: Plant manager
Previously owned cars: 318ci VF Valiant coupe, 351ci ’64 Fairlane compact, 540ci ’73 Kingswood ute
Dream car: Own it (just need to turn it into a nitrous Doorslammer)
Why the GTO: I have always wanted a big-tyred car
Build time: Initial build time six months but are they ever really finished?
Length of ownership: Approx. two years
Michael thanks: My wife Marie and brother-in-law Darren Saunders (for talking me into it). My children Kayley and Logan. My father Joe Sr for his support and sponsorship. Johnny and Graham from Magnum Automotive for the engine and ongoing support. Carl Jensen from C&M Performance for the tuning and wiring of the car. Autotrans for the transmission and converter. Rylock for sponsorship. Shane at Segedins for all the help.

1966 Pontiac GTO – Specifcations

Engine: 540ci (8849cc) big block Chev, Dart Big M block, Callies 4250 crank, Manley H-beam rods, JE pistons 13.5:1 compression ratio, Dart 310cc head ported to 360cc, Magnum custom ground cam, Dart high-rise intake, 1090cfm King Demon carb, Zex 4500 nitrous kit, 40-litre fuel cell, 300 MagnaFuel pump, -10 alloy fuel line to MagnaFuel two-port regulator, four-litre jazz fuel cell in engine bay, Comp 140 fuel pump for the nitrous, MSD Digital-7 Plus, MSD Pro Power HVC coil, MSD 8.5mm spark plug wires, MSD billet distributor, Hooker Super Comp headers, 2.125-inch primaries, four-inch collectors, alloy radiator, Moroso electric water pump
Driveline: TH400 transmission, 5000rpm stall converter, manual valve body, reversed shift pattern, 12-bolt diff, 4.56:1 gears, full spool, billet caps, 35-spline high-torque axles, custom driveshaft
Suspension: Ladder bar with Koni adjustable coil-overs, QA1 coil-over adjustable front shocks
Brakes: Discs all round
Wheels/Tyres: 15×4- and 15×15-inch Weld Racing Draglite rims, Mickey Thompson Frontrunner tyres, Mickey Thompson 32×17.5×15 E/T Street rear tyres
Exterior: Fibreglass hood, 4.5-inch cowl, fibreglass boot, Debear 411 black
Chassis: Mark Williams back half
Interior: Pro high-back seats, B&M Mega shifter, Auto Meter gauges, 10-point roll cage, custom dash, five-point harness
Performance: 872hp (650kW) at the wheels, 8.90 at 149mph (240kph)

Words: Todd Wylie Photos: Adam Croy

This article is from NZV8 issue 47. Click here to check it out.