Building a car can mean a lot of different things to all involved. For some it can mean signing a cheque or swiping an Eftpos card, while for others it can mean hours upon hours covered in grease in the workshop. While each of these tactics have their merits, despite all the late nights, the DIY style has to be more rewarding. Sure, when you’re lying under a car covered in oil, with bits of dirt in your eyes at 3am, you may wish you had just paid someone to do the work, but once the job is finished and you look back, the sense of satisfaction will make it all seem worth it. So it starts again, the very next day, after swearing you would never touch the car again, you’re back at it, working on yet another piece of the puzzle.
At least this is how it goes for me, and I’m pretty sure that Marcus Hammett is of the exact same opinion. However, the stunning 1991 Honda Integra XSi you see before you was not built by just 19-year-old Marcus — his boys were there every step of the way. Around 12-months ago, after having already owned the car for around a year-and-a-half, the boys decided they would like to enter a show with it. But to do that a whole lot of work had to be done, and just to add a little pressure, the show was three months; away. Sure, you say three months that’s not a problem, heaps of time. That is until you sit back and look at your own car’s progress over the same time period, and realise exactly how much of a nightmare job it is.
First on the agenda was to strip the vehicle back to a shell, including engine, interior and body panels. With bits of the body lying around the shed, work began on fitting a Foxton Aerotech body kit, which in turn received plenty of customisation. A WRX front lip was grafted to the Foxton front bumper and vents added to each side. The front guards were reattached to the vehicle with Foxton side skirts moulded on front and rear. Before they could be moulded to the rear, however, the guards were flared out to allow larger and wider wheels, and to provide a unique look at the same time. The standard side mouldings were removed and smoothed over, as was the original lock from the boot. Although carbon fibre bonnets are available for the DA-shaped Integra, the boys wanted to design and build their own bonnet based on the original. Firstly, polystyrene moulds were made to which fibreglass vents were moulded. The end result is not too dissimilar from the look of American-sourced Black Widow body kits that fetch a reasonable sum of money.
To complete the custom look, both head and taillights were customised and the indicators replaced with green items. As the shell was up on blocks, it made sense to crawl below and fit a neon light kit at the same time, and as the plan was for green paint, a green Fusion kit now lives well out of sight under the vehicle.
With every single panel smoothed off by Marcus and his crew, the car was fitted with coil-over suspension and a set of standard wheels and rolled off to the painters. While there Holden Hot House Green was flawlessly applied inside and out so no original colour was visible. Once back at the workshop, the boys started to piece the vehicle back together, but no parts were to be left stock standard. The B16A engine had never missed a beat, but just didn’t provide the power the lads were after, so was quickly fitted with a custom exhaust manifold and VF10 turbocharger.
The rocker cover was sent off to be painted, while a set of aftermarket, turbo friendly cams were installed. With the bottom end still stock-standard, a lot of attention went into making sure the car would run happily and not meltdown. To do this, a rising rate fuel pressure regulator was attached to the standard fuel rail and an aftermarket chip added to the ECU, as well as a Gizzmo fuel cut defender. Boost levels are controlled with a Turbosmart boost controller and vented by a Turbosmart blow-off valve attached to the custom 2.5-inch piping. Mated to the piping, and taking pride of place in the front bumper, is a custom 250x500x75mm intercooler, which sees to it that the hot Canterbury air is chilled adequately.
To ensure boost doesn’t blow out the fire, an MSD 2 coil pack was added, along with 8mm Top Gun leads and platinum gold sparkplugs. The boys knew the engine could only inhale what it could exhale, so custom-built a 2.5-inch exhaust with twin Autotechnia mufflers before adding a Blitz air filter to the intake side. As if all this was not enough, they decided they wanted some giggle gas to increase power even more. So before the standard intake manifold was re-installed to the detailed motor, a wet NOS kit was added. Before the gearbox was reattached to the motor, the lads installed a heavy-duty clutch to ensure the power made it to the ground.
With the engine dropped in, a front strut brace was added and the aforementioned coil-overs wound down in preparation for a set of 17×8-inch ANZ Trilogy wheels. Before the Kumho-wearing wheels were attached though, a set of Mintex heavy-duty pads were added to the standard brake callipers.
With the vehicle now able to drive, the interior needed to receive similar treatment before being reinstalled. As Marcus is a canvas fabricator, he thought he would try his hand at an interior re-trim in grey and black vinyl. No part of the interior would miss out on the spruce up except the dashboard, which was already black from the factory. The dashboard did, however, receive a hoard of gauges to keep an eye on how the engine was going, while up the re-trimmed A pillar sit even more white-faced gauges. To make sure the original cluster didn’t look out of place, the surround also received a coat of green paint and the dials themselves replaced with white items. Neither the standard steering wheel or gear knob were up to the boys’ expectations so were binned in favour of a Sportline steering wheel and Momo knob.
As the boys hadn’t driven the car, they didn’t know the turbo VTEC engine would provide a sweet tune that could be listened to for hours on end, so decided a decent stereo was needed just in case. Starting with a Sony CDX-M850mp head unit, signals are split to a Sony XM2156GTX amplifier and another Sony 600W amplifier. From there, front fill is taken care of by Sony 6.5-inch components hidden behind stainless grills in the standard location.
Down the rear, Sony 6x9s were added to provide full range to any rear seat passengers. In the boot resides a matching pair of Sony 12-inch subwoofers mounted into a custom trimmed box — again built and trimmed by Marcus and the lads. By the time the car was finally fired up, it was 3am on the day of the show. So a few hours sleep and the boys made their debut, where the car was well received by all who saw it. But as with most car builders, when the project appears to be finished, it just means it’s time to start all over again, as it just doesn’t seem right to get a full nights sleep and not be in the shed.
So, the boys have taken it upon themselves to build another Integra, this time with drag racing as the main intent.
If they keep the same attention to detail, and the same work all night, every night approach, I’m sure it won’t be long before we see a tired bunch of lads standing at the strip watching their newest creation. Tired or not, the smiles give away the fact they wouldn’t have it any other way.
1991 Honda Integra XSI
ENGINE: B16A 1.6L DOHC VTEC, aftermarket cams, Blitz air filter, VF10 Turbo, Turbosmart blow-off valve, 250x500mm intercooler, 2.5-inch piping, custom exhaust manifold, rising rate fuel pressure regulator, MSD 2 coil pack, Top Gun 8mm leads, Platinum gold plugs, 2x Autotechnia mufflers, 4-inch tip, 2.5-inch exhaust, aftermarket chip, Turbosmart boost controller, Spoon VTEC controller, Gizzmo fuel cut defender, Wet NOS Kit
DRIVELINE: Heavy duty clutch
SUSPENSION/BRAKES: Coil-overs, front strut brace, Brakes: Mintex pads
WHEELS AND TYRES: 17×8-inch ANZ Trilogy with 215/40R17 Kumho tires
EXTERIOR: Custom bonnet, flared rear guards, modified Foxton front bumper, WRX front lip, Moulded Foxton side skirts, Hot House green paint, under-car neon lighting, modified front and rear lights, green indicators, boot lock removed, removed side stripes,
INTERIOR: Re-trimmed seats front and rear, Sportline steering wheel, Momo gear knob, Momo Pedals, Auto Gauge boost, oil temp, oil pres gauges, Autometer air/fuel ratio meter, 5-inch Monster tacho, twin shift lights, white faced dials, re-trimmed door panels, modified dashboard, green interior lighting
ICE: Sony CDX-M850mp headunit, Sony XM2165GTX amp, Sony 600W amp, 2x Sony XS-L1290 subs, Sony XS-V1633 6.5-inch components, Sony XS-V6933 6×9-inch speakers
OCCUPATION: Canvas fabricator
PREVIOUSLY OWNED CARS: ’84 Honda Civic, 2 work hacks
DREAM CAR: Holden Maloo Ute, 6 speed
WHY THE INTEGRA: Cheap good-looking car, easy to modify
BUILD TIME: 12 Months
LENGTH OF OWNERSHIP: 2.5-years
MARCUS THANKS: My family, all the boys that have helped out, Shannon and Ross @ Plating solutions, all the guys at Ellesmere Motor Bodies, Adrian at Jap Race, Justin Pickford, and my boss Grant for all the time off and use of the workshop.
The Dyson name is synonymous with the OZ rotary drag racing scene. and it’s not by chance.
Reading through the spec sheet sent to me by Gold Coast-based driver/car builder Craig Dyson, I couldn’t help but be impressed. This wasn’t a huge surprise. The Dyson name is synonymous with top-notch rotary vehicles, thanks not only to the internationally acclaimed Dyson Rotary workshop, but also to the vehicles the Dysons have produced. Craig’s older brother, Wayne, was the founder of Dyson Rotary, and is known as the godfather of Australian rotary drag racing; he’s been playing with Mazda RX vehicles for just about longer than anyone in Oz. These days it’s Craig who runs the shop, and he’s been associated with dozens of impressive vehicles. Wayne’s son Andrew has also campaigned a highly competitive Series 6 RX-7 and currently has a rotary-powered rail in the build.
Being surrounded by family like this, and having a big hand in building competitive cars for customers, it’s natural that Craig has always had cool toys too. His favourite of the many he has owned is this 1990 Series 4 RX-7. Having owned the car for 12 years now, it’s fair to say Craig and the car have seen their ups and downs. But recently things have only been on the up.
For the last five years the Series 4 has been running 8-second passes. But as we all know, the allure of speed and thrill of the chase almost always require a lot of hard work and money.
In its previous guise the vehicle had been 'rear halved’, meaning that from the driver’s seat forward the chassis rails were intact. For the current build, however, the entire chassis was produced from lightweight chromoly. In an attempt to increase track stability and aerodynamics, the front of the vehicle is now a full six inches longer than standard. Along with major changes to the chassis came the addition of an entirely new engine package. Despite having previously been the fastest 13B in Australia, the old engine has made way for a methanol-fuelled 20B triple rotor.
It’s not only top shelf parts that have gone into producing the highly capable power plant, but two decades’ worth of Craig and Wayne’s combined knowledge as well. The aim for the power plant was to propel the vehicle deep into the seven-second zone, so it’s got all the tricks you would expect in such a package. To limit engine twist the motor has been pieced together with large custom dowels, and is mounted to the chassis both front and rear. The custom porting each housing has received is of a secret specification; Craig’s keeping it close to his chest and well away from the opposition.
With a serious amount of exhaust gas being produced by the three-rotor engine, Craig decided to run with a turbo that would be unfeasibly large for any other combination. The Turbonetics Super Thumper turbo has a 101mm compressor wheel and is so heavy that the custom exhaust manifold is as well braced as a small building. As the turbo builds boost on the start line thanks to its launch control system, the intake charge heats rapidly. The cure for this is a PWR ice-air intercooler that, come race day, is filled with dry ice to produce single digit intake temperatures. The 5-inch intake pipe that exits the cooler is fitted with twin Turbosmart blow-off valves before joining up to the Graphic Skills Racing intake manifold. This larger-than-life intake manifold and its associated fuel system dwarf the engine. Then again, the turbo takes away any attention the engine would receive anyway. Supplying enough fuel for the thirsty engine is a complicated feat in itself. The small, front-mounted aluminium methanol tank is dehydrated by an Enderly mechanical fuel pump, which feeds into five -10 lines. Each line feeds into a custom fuel rail fitted with three 1700cc injectors. That’s a total of 15 massive 1700cc injectors, which equates to a possible 25 litres of fuel being injected per minute from a fuel tank with a maximum capacity of just 20 litres. Completing the mammoth fuel system are a handful of SX regulators, metre upon metre of braided fuel line and a high speed return line. To cleanly ignite the high volume of fuel in each cylinder, six Mercury coils have been installed, one per plug. These feed current through Hurricane leads into NGK plugs, and the resulting combination exits through a 5-inch side pipe. Next to this are twin 2.25-inch waste gate screamer pipes from the twin Turbosmart 40mm Pro Gate wastegates. Both ’gates are regulated through the latest Turbosmart E-boost II boost controller, which works in conjunction with a MoTeC M800 engine management system. The complicated ignition system adds to the electronic trickery by utilising not one, but two MoTeC 4-channel CDI ignition control units. The resulting power produced by the 20B is around 1300hp, yet Craig assures us there is room for even more.
At this level of drag racing every hundredth of a second counts, and that’s why a Lenco CS3 magnesium-cased gearbox was chosen. Not only is the box lightweight and almost indestructible, but it also shifts through the cogs almost instantaneously. This speed is due to the air shift system, which allows Craig to punch a button for each gear he wants to select. Providing the smooth changes are a custom direct flywheel and twin plate slider clutch.
From here, power is transmitted through a custom 4-inch driveshaft with billet ends to a custom chromoly diff. Inside the diff are a Strange Pro Stock centre and 35-spline Strange axles. The tough diff setup is secured and suspended by a custom 4-link suspension arrangement with Koni double adjustable shocks. Mounted to each end of the diff are Wilwood 10-inch discs and callipers. These are hidden in behind the 15×15-inch Max Beadlock rims and 33×16.5×15-inch Hoosier tyres.
Up front, the tyres are at the other end of the scale, at just 4.5-inches wide and 15-inches in diameter. The wheels these are fitted to are ultra-lightweight Aluminstar billet alloys. Holding the front end up are quite possibly the shortest King springs in existence, along with custom lower arms and strut tops built into the roll cage.
With the stretch in the chassis, the original panels could no longer be fitted, so a carbon fibre one-piece nose cone was constructed. The signature Series 4 bonnet scoop has been skilfully moulded in, as has an impressive intake straight into the mouth of the turbo. The roof and rear quarters of the body shell remain steel, while the doors are fibreglass, and all windows have been replaced with lightweight Plexiglass.
The interior of the vehicle is every bit as purposeful as the exterior. Craig is seated in a Kirkey aluminium seat, and all attention is focused on the quick-release steering wheel and centrally mounted shift light.
It’s taken a few years for the vehicle to return to the strip in its new form. But the hard work has already paid off, with Craig running a new personal best ET of 7.45 @ 305kph after just a handful of race meetings. That time is quicker than any import in this country and currently positions the RX-7 as the sixth fastest rotary in Australia. This is up against vehicles that have been campaigning their current setups for years, and with far larger budgets behind them.
And with the car having taken a total of 12 years to build, on and off, Craig won’t be happy until he’s taken back the number one spot.
1990 Mazda RX-7 Series 4 – Specifications
Engine: Mazda 20B 3-rotor, Dyson race porting, doweled, balanced rotating assembly, Guru crank, custom studs, Graphic Skills intake manifold, Turbonetics 101 Super Thumper turbo, 2x Turbo-smart Pro Gate external wastegates, 2x Turbosmart Type II blow-off valves, PWR dry ice intercooler, Enderly 11A mechanical fuel pump, 15x1700cc injectors, 2x SX fuel pressure regulators, 1x high-speed return, 2x MoTeC 4-channel CDI, 6x Mercury coils, Hurricane leads, 5-inch side exit exhaust, 2×2.5-inch screamer pipes, PWR radiator, MoTeC M800 ECU, Turbosmart e-Boost II boost controller
Driveline: Lenco CS3 magnesium case 5-speed gearbox, twin-plate slider clutch, custom direct clutch and flywheel, custom chromoly sheet metal diff housing, full Strange Pro Stock centre, titanium yoke, 4-inch driveshaft, billet ends
Suspension: Koni double adjustable rear shocks, Strange front alloy shocks, King springs, 4-link, custom sway bar, custom track locator, chromoly wheelie bars
Brakes: Strange front callipers/rotors, spindle mount rims, Wilwood 10-inch disc rear
Wheels/tyres: Aluminstar spindle mount rims, 25x15x4.5-inch tyres, rear Max beadlock 15×15-inch rims, 33×16.5×15 tyres
Exterior: 6-inch chassis stretch, Plexiglass windows, carbon fibre nose cone
Interior: Kirkey aluminium seats, quick release steering wheel, air shift, shift light
Performance: Dyno Power — 1300hp, 0-400m —7.45 @ 305kph
Driver Profile – Craig Dyson
Occupation: Rotary mechanic
Previously owned cars: Too many to list
Dream car: This car on a new chassis
Why the RX-7? The love of rotaries and the need to go faster
Length of Ownership: 11 years
Craig thanks: Steven Cockerill, Nick Holmes, Shane, Thunder Road Race Cars, Phill @ Graphic Skills, Drew @ PWR, Roscoe’s Paint Depot, Bryce @ Miller Signs, Pennzoil, Damien @ McKern and Associates Charted Accountants, and of course Dyson Rotary
Words Todd Wylie Photos Quinn Hamill
The compressor turbine draws in a large volume of air, forcing it into the engine by spinning at a very high speed.
Air pressure in the intake builds because the turbocharger’s output exceeds the engine’s volumetric flow — this is called boost.
The speed at which the turbine assembly spins is proportional to the pressure of the compressed air, and the total mass of air being forced into the engine.
Turbos can spin at many tens of thousands of revs per minute, and the speed must be controlled. A wastegate is the most common mechanical control system, and is often further augmented by an electronic boost controller. The wastegate’s main function is to allow some of the exhaust gas to bypass the turbine when the set intake pressure is achieved.
The boost threshold is the minimum engine RPM at which the exhaust is flowing sufficient air to allow the turbo to produce noticeable boost — as they are powered by the movement of exhaust gases, without enough exhaust gas velocity, air cannot be forced into the engine. For example, if you were travelling and the engine was ticking over 1500rpm, and your boost threshold was 2000rpm you would experience a delay between when you pushed your accelerator and the engine revs rising enough to meet the turbo’s requirement to produce boost. This is not lag, this is a result of the engine not revving fast enough to generate boost at all.
Advantages of turbocharging
- More specific power over a naturally aspirated (NA) engine — it means an engine can produce more power for its size. Turbo 1.5-litre Formula 1 engines regularly produced in excess of 1000bhp.
- Reuse of excess exhaust heat (it gets channelled into the turbocharger to increase boost to the engine) means the engine runs more efficiently than NA or supercharged engines.
- A turbocharger is smaller, lighter and easier to fit than a supercharger, and it is more consistent than, for example, a nitrous oxide kit
- Because a small engine can be made to produce the power of a huge NA engine, fuel economy is often better on a per kW basis.
Disadvantages of turbocharging
- Turbo lag, especially on large turbos. A large turbo may give more peak power, but can take more time to spool up.
- Driveability may be compromised, particularly when the boost threshold is approached and suddenly a surge of power is too much for the tyres to cope with, causing understeer/oversteer (depending on which wheels are driven). This reduces the useable power band of the engine, and leads to more wear and tear on the drivetrain.
- Turbochargers are costly to add to NA engines, and add complexity. Adding a turbo can often cause a cascade of other engine modifications to cope with the increased power, such as exhaust manifold, intercooler, gauges, plumbing, lubrication, and possibly even the block and pistons.
Lowering the rotational inertia of the turbo’s turbine will allow it to spool up more quickly, e.g. by using lighter parts that take less energy to turn. Ceramic turbines can help here, but they are limited in their maximum boost and are relatively fragile.
Changing the aspect ratio of the turbine by reducing the diameter and increasing the gas-flow path length, as well as using reduced-friction foil bearings will also reduce lag.
A common method of minimising turbo lag is to clip the turbine wheel. A minute portion is clipped off the tip of each blade of the turbine wheel, reducing the surface area of the rotating blades, and placing less restriction on the escaping exhaust gases. This results in less impedance at low speeds, giving more low-end torque. To counter the negative effects of this, the effective boost RPM is raised slightly higher.
Using two smaller turbos as opposed to one huge one will help. Nissan, Subaru and Mazda have all done this, for example the twin-turbo Legacys (sequential), or the twin-turbo Skylines (parallel). Two small turbos produce the same or more total boost than a large single turbo, but because they’re smaller they have less inertia and therefore reach their optimum boost delivery sooner.
The sequential turbos tend to work with one small turbo being active over the entire rev range, and a larger turbo that comes online at high revs. Early designs had one turbo for low revs and one turbo for high revs which sometimes caused a noticeable drop in power between the boost from one falling off and the boost from the other reaching maximum.
Sequential twin turbos are far more complicated than single or parallel twin turbos because valves and additional piping are required to control the direction of the exhaust gases.
Turbo lag is a delay from when you push the accelerator and when you feel the turbo kick in. This is caused by the time taken for the exhaust system driving the turbine in the turbo to reach the required pressure, and for the turbine to spin fast enough to supply boost pressure.
Older turbo cars were far more susceptible to turbo lag. Modern technology has largely overcome it.
A large volume of air flows between the turbo and the inlet of the engine, forced by the high-revolution turbine in a turbocharger. When the throttle is wide open this air travels into the engine, but when the throttle is closed compressed air flows to the throttle valve and has nowhere to go.
This can cause a surge in pressure that can cause engine damage such as burst induction pipes. Additionally, the compressed air flows back towards the turbo (the only path it can take), slowing the turbo down suddenly. When power is applied again, this speed has to be built up again (causing turbo lag).
A blow-off valve is a vale fitted between the turbo and inlet which allows excess air pressure to escape. This air is usually recycled back into the turbo inlet, but can be vented into the atmosphere.
Venting to the atmosphere causes the signature blow-off valve woosh and it is easier to install because there is no additional plumbing. There is no significant performance benefit through venting into the atmosphere — just a louder, more showy sound.
Recycling the compressed air back into the turbo reduces this noise, and also keep the turbo spinning more effectively, particularly between gear changes.
Blow-off valves are usually operated by engine vacuum.
They are sometimes called dump valves.