A one-off custom? No, this stunner is planned for production…

But don’t ever, ever tell John Bettini and Greg Casey that they’ve created "a really neat MX5 replica".

The men who founded Bullet Supercars in Chinderah, NSW (right beside the Gold Coast actually) came up with something that has a startling resemblance to Mazda’s successful little open top sportster, yet the Bullet Supercar is very much an individual.

OK, so there are quite a few MX5 parts throughout the vehicle and the supercharged 1UZ-FE Lexus V8 engine isn’t entirely Australian, but that’s no different to Jaguar’s latest technology being Ford based or whatever.

Car manufacturers swap parts and technology at a crazy rate these days, yet there are solid reasons for Bullet Supercars following the MX5 and Lexus lines.

The Bullet roadster’s similarity to a Mazda MX5 is both a blessing and a curse.

For one thing, the MX 5 has completely re-defined the open top sports car theme in the modern era and its phenomenal success cannot be denied.

The marketing and promotional advantages of this are too tempting to resist, whilst the use of MX 5 basics such as seat belts, instruments and such like has also made the job of obtaining ADR (Australian Design Rules - all road going cars must comply in Australia) compliance relatively easier.

Yet at the same time it has to be constantly reinforced that this is not a kit or some mongrel special.

Thing is, see, that a Lexus 1UZ- FE engine hasn’t just been wedged into a butchered MX 5 chassis, and then covered with a load of custom bodywork to hide all the flaws.

Getting the design right
At ground level, the chassis is a high tensile space frame affair which is actually the eighth that Bullet have designed. Coming up with a good chassis design was no small achievement either.

As John Bettini said;

"Essentially we had to get all of our geometry correct, but it also had to be torsionally and beam stiff.

We actually get 12000Nm of force per degree of flex, which is twice the required standard for licensing in any Australian state, so it’s quite a stiff little car."

Incidentally, compared to the latest MX 5’s wheelbase of 2265mm, the Bullet measures in at 2332mm.

Attached to the four corners of the chassis are the suspension components - McPherson strut format at the front and coil over double wishbone at the rear.

Much of the suspension componentry - including the front A arms - is actually from the later model Series VI Mazda RX 7, but the 43mm diameter struts and springs wrapped around them front and back are the "Pro sport" combination from Aussie suspension specialists, King Springs.

Naturally, the struts have virtually infinite screw thread adjustment for spring pre-load.

As you’d expect, the supercharged Bullet supercars are fitted with decent brakes - 320mm rotors as a minimum at the pointy end, with 280mm rotors out back and four spot calipers all round. Brembo is the brand name on all of this gear and it’s likely to stay that way too.

But why a Lexus V8?
When it came to the all important power factor, the Lexus 1UZ-FE V8 engine was chosen for a number of reasons, not the least of which is its double bonus of lightness and power.

Australian automotive performance is still dominated by the single camshaft, 16-valve V8 engine format and whilst hordes of these in infinitely varying formats are readily available, using one on the Bullet Supercar would be like adding the anchor from the Queen Mary to the front of the car.

At 175 Kg, the alloy quad-cam, 32-valve Lexus V8 weighs in some 10 Kg lighter than the Chevy Gen III V8 engine which is presently powering top of the range Holden Commodores Down Under.

Just for interest’s sake, the older Chevy small block motors start tipping the scales at 260 Kg, whilst some of the Ford offerings are no better.

Depending on the year, specific model and market, the 1UZ-FE left Japan producing anywhere between 180 kW to 204 kW.

Whilst the cars that used the Lexus V8 were never officially brought to Australia, (although the newer generation of the engine with variable valve timing is in the latest Toyota 4WDs) the 204kW SC 400 has been a firm favourite through the ‘grey’ import yards for a number of years now.

Other benefits of the engine include a massive oil pick up and six-bolt (via a cross bolt system) bottom end. In America, these engines with stock bottom ends are producing upwards of 800Hp and a number of Aussies are now on the same track.

In this case study - with a Sprintex S90 supercharger and some internal mods - the Bullet Supercar is quoted as producing "Just over 400Hp, or 290kW in more modern language."

The use of a Sprintex supercharger is another purely Australian connection and Perth’s Advanced Engine Components (AEC) now own Bullet Supercars and Sprintex Superchargers.

If AEC sounds familiar, it probably is.

The company has been in the press quite a bit recently as it was heavily involved with the 300+ Sprintex supercharged quad-cam Mustang engined two-door Ford Falcon coupe, that Ford Australia is hopefully going to manufacture in limited numbers by the end of this year.

Not that this is the place to discuss company structures and such like, suffice it to say that AEC have an impressive arsenal of expertise and product in their armoury.

The company has also been achieving phenominal success lately with emissions standards from their CNG (Compressed Natural Gas) system in Europe, but that’s another story for another time !

Back to the Bullet’s Lexus engine. Considering the strength of the 1UZ-FE’s bottom end, internal mods for the Bullet were based more on meticulous preparation.

All new bearings were added, while custom pistons were machined from undisclosed blanks to lower the compression ratio down from a stock 10:1 to a more boost friendly 9:1.

In just about every other way possible the engine was balanced and blueprinted, before the heads were mildly worked, particularly around the exhaust ports.

Ivan Tighe then ground up four timing sticks (remember, this is a quad-cam V8), which offer more in the way of increased overlap than lift.

Exact cam figures were not forthcoming and there is also believed to be some ‘mystery’ surrounding the valve springs.

Obviously, the addition of the supercharger required a custom manifold, which was fabricated by an individual known simply as Clyde Carstairs.

Fuelling with any supercharged engine is critical and whilst the Bullet uses what is essentially the original Lexus EFI hardware, there are a few upgrades including a Bosch Motorsport pump.

The injectors are stock Lexus items, albeit with two additional Bosch Motorsport squirters plumbed into the back of the supercharger’s intake plenum.

These begin to operate at minimum duty cycle from 2psi, ramping up to near maximum duty cycle at maximum boost of 12 psi.

In the early stages, engine management was handled by Microtech MT 8 electronics, but as with the 300+ Ford coupe, AEC’s own highly advanced ECU is likely to be applied to future Bullets.

There’s still some sorting out to be done on this front, especially in regards to satisfying Australia’s ADR 3701 standard for emissions and that will also no doubt have a bearing on the exhaust system of any future Bullet production cars.

In this particular case, a twin 2 ½" system with twin cats was mated to AEC’s own headers.

The 400-odd Hp produced by the Bullet roadster is starting to get into serious territory, yet the original Lexus automatic gearbox remains - albeit converted to tiptronic operation.

There should be the option of a Borg Warner 5-speed manual box, and a quad cam Mustang engine might be a possibility too.

The tailshaft on the first supercharged V8 Bullet roadster is a 3" Gibbs Engineering item with US sourced uni joints, while the IRS LSD diff is a Borg Warner item as found in an everyday Holden Commodore.

Readily available and in a range of configurations, the Borg Warner diff’ is a solid choice.

Getting the look (and function) right
Right at the top of the story, it was indicated that the Bullet boys didn’t simply throw a mish-mash of body parts at the car to cover up all the mechanicals.

That in itself was quite an accurate assessment, as an intense amount of thought and design went into not only how the car looks, but how everything actually functions.

The bonnet, for example, comes off completely in about 10 minutes (as we found during our photo shoots !), although with practice this time could be reduced by a two-man team to about 1 minute.

This actually hints at one of Bullet’s ultimate goals - GTP racing here in Australia.

The number of cars a manufacturer needs to produce in order to qualify a car for GTP racing varies a bit, but if Bullet does make it to the starting grid, then the Porsches, Ferraris and such like which dominate the class now will be in for some stiff competition.

AEC’s future racing plans in this area are unclear, but here’s hoping !

Back to the bodywork and on an overall scale, the final combination was achieved after several thousand hours. A full mock up in clay was even created, re-shaped, deliberated over ... you get the picture.

The use of the word combination is accurate too, as the car features both original MX 5 panels and parts manufactured by Bullet in their Chinderah factory.

The boot lid and doors are actually the only MX 5 body panels, as the front and rear quarter panels, rear apron, side skirts and bonnet are all fibreglass reinforced plastic.

The panels are bonded together and to the chassis in late model Lotus Elise fashion - that is with space age bonding epoxy (in other words, really high tech’ glue!).

All of the body panels flow together very well and the car has been wrapped up with those stunning 17" ‘Blade’ rims which are the latest design from ROH.

The car’s purpose as an open top sportster is nowhere more evident however than in the cabin, with simplicity the main theme.

The seats are another Bullet manufactured item, albeit using an MX 5 base. Likewise, the instruments are pure MX 5, but look closely and you’ll see the VDO electronic 300kmh speedo.

Oh, and just in case you’re wondering, there will be hard and soft top options for when the weather turns nasty.

As a complete package, the Bullet Supercar is a stunner which sets completely new standards for the open top sports car theme.

After all, there are open top cars out there that claim to be ‘sportsters’, yet Ford’s Capri, numerous one-offs from BMW, Mercedes and even the occasional ‘chop top’ cannot boast the Bullet roadster’s looks let alone performance.