Four-second 2500hp radial Gemini – CASPER

They call it ‘Casper’, but this four-second, 2500hp Gemini is more terrifying demon than friendly ghost

Photographers: Steve Kelly

SOME of you may remember Queenslander Nikki Hepburn, who rose to drag racing stardom a few years back by running into the 6.80s in a twin-turbo, big block-powered Gemini called Casper – half the time with the car up on the back wheels.

First published in the November 2021 issue of Street Machine

Her little Gemini became an overnight sensation, but she eventually parked the car and went on to build a Toyota 86 with a twin-cam, turbo six-cylinder Land Cruiser motor. She ended up taking the 86 on tour to the USA and running 6.50s in Florida. What a story!

Nikki (surname now Coy after getting married) recently sold the 86 and has moved on to other things in life. As for Casper, the old Gemini roller was a shadow of its former self, and had sat in the shed for years until Nikki’s dad, Clint, decided to throw his hat in the ring. Despite being around drag racing all his life, Clint had never actually raced before.

Nevertheless, as a man who does nothing by halves, he was determined to turn the Gem into one of the top radial cars in Australia.

Before spending a cent, Clint sat down with Justin Simpson from Horsepower Solutions to formulate a plan for building a three-second radial car. Then it was time to start whipping Casper into shape.

“The old car needed a lot of work,” Clint says. “We had to step up from a back-half car to a full tube, double-frame-rail 25.2 chassis with carbonfibre panels and just steel roof and quarters.”

Clint cut out the floor and built the entire chassis himself over a two-year period, tacking every bar into place and then getting it fully welded.

He and his daughter had previously used a USA-built Shafiroff motor in the car and returned to the same builder for a top-of-the-line, all-aluminium 540ci Brodix long engine rated to 3500hp.

“In addition to making every carbonfibre panel on the car, Benny Bray hooked me up with a pair of 98mm Pro Mod turbos,” Clint says. “You really need them that big to make this deal work.”

In addition to all the fab work completed by Clint, his shop worker Daniel Swanney mounted and plumbed the Turbosmart wastegates and fabbed up the whole hot side in stainless, before moving on to the cold side.

The big-block Chev engine is an impressive bit of gear. Some of the features include a CNC billet inlet manifold with 16 Billet Atomizer 550lb injectors; Aeromotive 21gpm cam-driven fuel pump and matching regulator; Haltech Smart Coils; Haltech ECU; and sensors for coolant pressure, EGTs, wheel speed, driveshaft, oil temp and more.

The spending didn’t stop there, with the purchase of an M&M Transmissions all-billet, two-speed TH400 featuring a lock-up billet converter, double dump valves, and every bell and whistle in the catalogue.

Underneath the car are Menscer shocks on all corners and a Race Products sheet-metal floater rear end in chrome-moly with a Strange bolt-through centre, 10-inch crown wheel, 40-spline axles and Wilwood brakes.

With the combination all together, Clint headed off to the hub dyno for a light tune-up shakedown. On just 5psi of boost, the 540-cube Chevy pushed out a hefty 2200rwhp, and with another couple of pounds, the needle was bumped to an impressive 2500rwhp. When you consider this combination is built for 40psi of boost, there is a hell of a lot of meat left on the bone.

In race weight, this Gem tips the scales at just 2400lb and will be packing 3500hp when fully sorted. With a 92-inch wheelbase and on a 315 radial, it’s going to be a handful.

The Gemini’s first outing after the rebuild was pretty exciting. Straight off the trailer on a soft tune, the car went 1.08 in the 60, with a 4.31@172mph over the eighth-mile on just 18psi of boost!

“Macca from Suspension Dynamics did a great job of setting up the car, and when I let go of the button at the track it will make a pass without me holding the wheel – it goes dead-straight,” Clint says. “At the moment the car is pretty tame, but we are heading into the threes; we will sneak up on everyone, just quietly, and get it done.”

When you look at the quality of the build and the huge financial investment, you can’t help but be impressed by Clint’s commitment, especially given he built the chassis and most of the car himself in his back shed! The easy answer would have been to buy a turn-key car at a fraction of the cost, with a longer wheelbase and with the numbers already on the board. “Everyone says I’m crazy to build a car like this – too much motor, not enough wheelbase – but we’ve put a massive amount of effort into the steering and suspension set-up,” Clint says.

From here, it’s just a matter of more track time, and when you run the numbers on this car, it adds up to quick times ahead.

One thing’s for sure: this little ‘friendly ghost’ will soon be giving competitors a scare.

Photographers: Steve Kelly