Mazda RX-7 - The Last Rotary Racer

Rotary Revolution turns dream to reality and to success with ambitious programme to develop RX-7 racers.

Date Published: 24 Sep 2019
Mazda RX-7 - The Last Rotary Racer

Over the last decade the Thai motorsport landscape has changed beyond recognition as competitiveness and professionalism have reached skywards. It’s left the sport in a rapid state of flux.

While this has been an unquestioned win-win for Thai motorsport there have been some fundamental changes in the landscape as a result of those dizzying changes.

The Last Rotary Racer

The Last Rotary Racer

One shift has been the loss of the long and rich tradition of Thai racecar construction as local craftsmen have been unable to match the sophistication and scale of the turn-key racecars that have flooded in from Europe. Prestigious brands such as Ferrari, Porsche, Audi and Lamborghini now dominate the landscape.

Unable to match up, the era of local racecar production has simply come to a juddering halt, only the once-mighty factory Toyota team still fields a car at the top end of the tree that has been built in Thailand, but even for its participation in the highest-level category, Super Car GT3, it now has shipped in a ready-made GT300 machine.

The Last Rotary Racer

All seems lost in this area. But not quite. One local tuner, Rotary Revolution, owned by Mr Titapon Phaojinda who is regarded as South East Asia’s foremost expert on ‘rotary’ road and race cars, three years ago decided to fight back and he launched an ambitious project to build a production run of purpose built new racecars based on Mazda’s iconic RX-7.

The Last Rotary Racer

The Last Rotary Racer

The Last Rotary Racer

The Last Rotary Racer

It’s a story of passion – and big dreams. But unlike most dreamers Titapon has pursued his dream to a successful conclusion and delivered something that’s a little bit special to the Thai motorsport landscape.

But first, to rewind a decade. Rotary Revolution wanted to prove they could build winning cars themselves and keep a long-standing Thai tradition of motorsport preparation alive and well. Titapon doesn’t just keeps the rotary flame alive, he believes it’s still a winner, that it can still beat the rest and that’s a point he wanted to prove. His company already had a long and successful history in both the rotary tuning world and top-level Thai motorsport having been the first to tune ‘rotary’ cars in Thailand and then going racing in Super Car for more than half a decade with solid results.

The Last Rotary Racer

They originally went on track without the aim of winning, rather they wanted to prove the reliability of ‘rotary’ power units in the extreme conditions associated with circuit racing and in particular the pressures that come with fighting it out in Thailand’s premier racing series, Super Car.

Aiming to silence doubters they more than justified their claims by recording not a single engine failure over five years of full season competition running a single car.

Responding in particular to a close-knit customer base that had seen the progress on track of the original car and were interested in a new breed of Thai built racecars that would return Japanese culture to the racing frontline, the new programme was born.

Ambitious to the extreme, the new run of racecars incorporates all that competition experience and after an almost two year gestation period for the project, the result was the creation of a special machine that clearly offered much potential to unlock, adding in thrills for the driver while being affordable to buy along with low running and maintenance costs.

The Last Rotary Racer

Creating a racecar that is not only effective but affordable are intrinsic to the ideals of Rotary Revolution. It’s also a beautiful machine, one the owner can admire – and that’s another ambition of the company, to create cars that are a visual treat.

Meeting the needs of a diverse customer base meant that Rotary Revolution created two ‘steps’ of racecar. One is a more lightly developed entry-level racecar for the ‘club’ racing end of the market while the other is a balls-out racer ready to take its place on of the most competitive grids.

Here we focus on the latter, an emotive racecar that excludes power and capability from every inch of its muscular yet still lithe frame, which also, importantly, retains all the DNA of the original. A new purposeful racing machine that is imbued with a slippery shape that is recognised worldwide.

The Last Rotary Racer

Drawing on the aerodynamic tradition of Japan’s ‘Super GT’ machines, this RX-7 racer has an aggressive stance and bulging surface features; its striking bodywork a mix of lightweight fiberglass with carbon fibre insert panels.

With custom designed tubular front and rear chassis sections, that allow for a lower ride height and thus lower centre of gravity, a completely new suspension that incorporates formula car-style pushrods at the rear, an increase in the length of the wheelbase, improved chassis stiffness, lightweight bodywork and a sophisticated aero pack, this is a no-compromise racecar that clearly proves that winning machines can still be built in Thailand.

The Last Rotary Racer

Technical Specifications

At the start of a 2-month built process the ‘donor’ production car chassis, which can be either supplied by the customer or sourced by Rotary Revolution, is first sent to the fabricator, a local company with more than 30 years’ experience building race chassis. The front and rear sections are removed and replaced with a tubular framework and repositioned structural chassis members to optimise the overall dynamics which including lowering the centre of gravity and repositioning the mounting points for the new suspension.

The Last Rotary Racer

The frontal chassis members are repositioned to improve the roll centre and they incorporate a new twin pipe structural member internally to facilitate strength and rigidity. The front subframe has been reduced in dimension (by approximately half from the original) with the rearmost section retained to allow the car to meet regulations, such as those from Thailand Super Series. The original engine mountings and their structural positions have also been retained for the same reason. The front crossbar is bolted in place to allow for fast access to the engine bay and to facilitate repairs at the racetrack.

The upgrades made to the chassis have allowed the wheelbase to be increased by 5 cm. While the car’s ride height is now lower, chassis rigidity is improved with the fitting a race roll cage and spot welding of the chassis sections.

The Last Rotary Racer

The new tubular chassis sections at both the front and rear allow for greater strength in the case of an accident and to improve rigidity to a required level. Balance is improved by the new arrangement as the roll centre is optimised.

The chassis includes new under floor sections for the exhaust system, which has a side exit just in front of the rear wheels, and a mandatory fireproof bulkhead situated between the cockpit and the rear compartment, which also houses the fuel cell.

The pedal box, which has been bespoke designed, the front and rear anti-roll bars and the air jacks are all fitted during the fabrication stage before the rolling chassis returns to Rotary Revolution for final assembly.

The Last Rotary Racer

Suspension & Steering
The suspension features larger, wider wishbones at the front which have repositioned mounting points on the new tubular frame due the lower ride height of the chassis and the changes in suspension geometry. The suspension is made of chromoly steel, which is lighter and stronger than alternatives.

At the rear there is a push rod suspension arrangement, in the style of a ‘formula car’. The original suspension system however can be retro fitted for use in series where pushrod arrangements aren’t permitted.

New adjustable racing anti-roll bars are fitted at the front and rear while all bushes use race standard nylon materials.

The steering rack is bespoke. It is mounted higher than in the production car due to the raised positioning of the new front chassis members, and it’s modified for faster turning response.

The Last Rotary Racer

The engine is built in-house and the unit feature upgrades to take into account the extreme pressures applied during racetrack use. Changes include using Apex seals to allow higher pressures and full porting. The turbo is also unique to this application.

Rebuilt engines are ‘run-in’ on a road car for 1,000 kms before being installed in the racecar.

One advantage of ‘rotary’ engines is low rebuilt costs when compared to conventional engines and this allows owners the option to set a rebuild for when they require and generally undertake it well inside the scheduled hour life of the individual unit. The low engine rebuild cost has a useful knock on in keeping the whole programme more cost effective.

The engine bay has been custom designed by Rotary Revolution’s engineering team to optimise the layout for component performance, cooling and to facilitate rapid maintenance.

The compact nature of the rotary engine allows for excellent packaging and it already has a much lower centre of gravity than conventional engines while its homologated position is quite central already meaning that it doesn’t require the engine to be repositioned to achieve better balance.

The wiring loom is a specially made design while the ECU has been mapped by Link to the characteristics of engine. Traction Control is an option.

The Last Rotary Racer

The engine is mated up to a 6-speed sequential gearbox that’s custom made for the car. The rear differential features internal component upgrades and is fed by an oil cooler with the fluid tank mounted in the rear compartment.

The tubular rear section suspension positioning has also been designed to make the differential easily accessible and ratios can be changed in a very short time.

There are in fact two separate rear cooler systems for the transmission and differential operated by separate pumps. The driveshaft hubs are of alloy material with racing specification seals.

The Last Rotary Racer

Fuel system
The car is equipped with a custom made ATL fuel cell which is centrally mounted in the rear compartment for the best balance. Paddles in the alloy fuel cell act to keep the fuel stable. A 60-litre capacity cell is standard while a 70-litre tank is optional.

The quick release rear bodywork cover allows for fast refuelling. Optionally, Rotary Revolution can fit a left- or right-hand-side flush fuel filler.

Another ground-breaking feature comes with the inclusion of a custom-made fuel cooler box. This is a first for a racing version of the RX-7 and arrives thanks to Rotary Revolution’s experience with this engine and a desire to improve efficiency by introducing a cooling system that will prevent any drop off in octane during the race, especially important in Thailand where race distances are increasing and temperatures are a significant factor.

The fuel cooler box, which features a quick release lid, houses a spiral arrangement of the fuel lines that are packed with dry ice in a simple operation that takes less than a minute to perform. This ensures that the fuel is kept at a lower temperature throughout a race. The fuel cell and the adjacently mounted fuel cooler box are enclosed in a fireproof compartment.

A full fireproof bulkhead is welded in place between the cockpit and rear compartment while an additional bolt-on bulkhead is incorporated above for rapid access.

The Last Rotary Racer

The car features a side exit exhaust system. This exits just in front of the left hand rear wheel and is a system that has been decided on by Rotary Revolution after more than five years of racing in Super Car with multiple positions being used as the engineers studied gas flows.

The muffler is custom made in Japan for the car and also comes as a result of the extensive racetrack development programme while a titanium muffler can be specified as an option.

To meet safety regulations the muffler is enclosed in a specially designed chassis section under where the passenger would normally sit and it’s fully wrapped in place.

Rotary Revolution has chosen PFC brakes with 6-pot at the front and 4-pot at the rear, together with ventilated/slotted discs of a bell type.

The Last Rotary Racer

Starting from a clear sheet of paper has allowed the company to layout everything with the aim of ease of convenience for the driver.

The seat and harnesses are homologated to FIA standards while the automatic fire extinguisher system meets local requirements. There is a ‘kill’ switch on the dashboard (and another on the external scuttle panel).

The dashboard shell section is custom made by Rotary Revolution and designed to give the car an RX-7 ‘feel’ while saving weight and being straightforward to remove.

There are oil and water temperature gauges in clear view of the driver. A data logger is mounted in the usual position in front of the steering wheel.

The Last Rotary Racer

The aero package is one of the car’s most striking features and has helped to quickly create a fan following. It closely follows Rotary Revolution’s long tradition of developing racecars that are inspired by the traditional aerodynamics associated with Japan’s Super GT Series.

Clearly this car pays homage to the RX-7 lineage, but equally clearly this is a car that aims to have its own unique identity.

The multi-curvatures of the engine cover have been enhanced, as has the sweep of the pillars into the glasshouse while the lines of the flanks add up to create a car that is aerodynamically efficient but also beautiful to look at.

Form follows function unquestionably in this racecar, but in this case beauty closely follows that form and function.

The Last Rotary Racer

The project engineers’ have evolved a shape that doesn’t just offer aerodynamic requirements that can be additionally tweaked for the demands of Thai motorsport (such as the smooth and high-speed FIA Grade 1 Chang International Circuit or the twisty and difficult surfaces of the Bangsaen Street Circuit) but also enhances weight savings and ease of replacement as well as rapid access.

In functional terms, Rotary Revolution didn’t want to compromise engine cooling requirements, particularly as the requirements of Thai motorsport are becoming more and more extreme as the levels of outright competitiveness are increasing pressure on machinery – something which has mostly driven out other Thai built car lineages.

However cooling requirements have been incorporated into the form to blend and in fact add to the aggressively visual nature. That means that as well as large cooling ducts in the front and the engine cover.

A jutting splitter manages airflow around a car that is structurally lower while the headlight units are custom-built by Rotary Revolution and the dip/turn signal units are imported from Japan.

The ‘Super GT’ styling inspirations can be seen over the length of the car including the airflow treatment of the ‘flick up’ wing sections, aero efficient enhanced side skirts that manage requirements along the side of the car and through to similar treatment applied to the rear wing sections.

Both the front and rear wings are designed to manage the air intake requirements of the upgraded braking system and exit the air in a manner that works with the aero.

The Last Rotary Racer

The rear bodywork section is a one-piece fiberglass unit with the ‘production’ RX-7 rear cosmetic panel and lights etched in and picked out in a dark colour to save weight and reduce component use but all the while still retaining the distinct visual features of the RX-7. The rear lights are LED type. Meanwhile, there is a custom-made diffuser.

The rear wing is sourced from Esprit in Japan and was in fact originally designed for the Super GT Honda NS-X programme. Rotary Revolution’s engineers tested and analysed this wing and found it best fitted their downforce needs. The mounting/positioning is custom to the car’s requirements.

The engine cover, rear cover, wings, front nose section, rear panel and doors are all custom made and designed for quick removal with a mix of bonnet pins, fasteners or quick release bolts used in different positions both in terms of accident repairs but also to allow for ease of access to major components.

The polycarbonate side windows are bespoke made by Rotary Revolution and include horizontal sliders.

Mazda RX-7 - The Last Rotary Racer

The materials used for the body panels are a mix of fiberglass and carbon fibre, which allows for all round weight savings, one of the key metrics of the programme.

All the fibreglass sections are produced from in-house moulds by Rotary Revolution, which means significant costs savings are achieved on replacement components.

The production twin wiper arrangement is dispensed with in favour of a single centrally positioned wiper, which is re-geared, and built to racing specifications to prevent lift at speed.

The Last Rotary Racer

Throughout the programme one of the key objectives has been weight saving with an emphasis being placed on using lighter materials and components.

That has resulted in a car that has a dry weight of just 1,070 kg. That compares very favourably to the racing RX-7 that Rotary revolution campaigned previously which weighed in at around 1,200 kg.

The new car has also been designed so that any additional weight ballast that might be required by an organiser can be incorporated in a manner that doesn’t compromise the balance of the car as far as is possible.

The Last Rotary Racer

The Last Rotary Racer

Life on track
The first car, finished in an eye-catching shade of ‘pink’, was an instant standout when it first hit the track three years ago and it ruffled feathers by winning its debut race, in the Open/Unlimited class of the then Nitto 3K Kumho Racing Car Thailand series.

The Last Rotary Racer

The team then headed for Super Car, running in the ‘GTC’ class which aims to embrace Japanese machines such as the RX-7 and Mitsubishi’s famous ‘Evo’. They scored big too, winning the Teams’ title along the way.

Titapon reckons it’s been a step-by-step progression to the front as the team first set about building the car before turning their attention to unlocking its potential, learning about it dynamically and slotting in the right final pieces in terms of the drivers and engineers.

He says that they haven’t really made any major upgrades since the original blueprint. “We have adjusted the suspension and the settings and learnt more about this,” Titapon explains. “The engine is the same, we’ve done nothing with the engine, only the ECU which we tuned with the tuner from Japan.”

The Last Rotary Racer

That was a big piece to be added to the jigsaw though with the arrival in the garage of legendary Japanese rotary tuner Toru Kumaki from Top Fuel racing. It’s not often the international engineers lurking in the Thai racing garages see much demand for ‘selfies’, but in Kumaki’s case there’s always a steady stream of paddock people wanting to have a photo taken with him.

“He’s been a friend of my dad from 20 years ago so he came to help us make the car faster. He has experience of World Time Attack and so much more and he looks after the ECU, tuning, collecting the data. He’s made a lot of difference to us. The car is old but the ECU system is a new one so we have put new technology in to help the car become faster.”

The Last Rotary Racer

Another personnel change was putting James Runacres into the ‘hot seat’. The 25-year-old British driver arrived after an early career spent in single-seaters and he’s really gelled with the team.

There were a few early growing pains in the relationship. “James came from Formula Renault so the car is quite different and he had a lot to learn,” says Titapon. “The car in size is very different, it’s not easy to turn like a formula car and he had a lot of problems with the braking because I think in Formula Renault you can just tap the brakes and turn, but GT cars are not like that, you have to apply the brakes much more slowly, so he’s learnt a lot with us.”

With a fast driver able to provide a benchmark for the team they went from packing out the numbers, which admittedly was central to their title, to chasing the wins.

The Last Rotary Racer

“James is very professional so he also teaches us things about the car and what he wants from it,” he continues. “For example, he loves to have a little bit of toe in, not have it set straight, so we adjusted that when he arrived and he understands the car very well, he says the car is hard to spin now, so he can go fast in the corners as he’s not afraid of spinning. Some of the settings we learn from him and he learns the car and we all work together to make him go faster.”

The Last Rotary Racer

So, for James how did he come to trade in his single seater path for a seat with Rotary Revolution? "I've loved rotary engines ever since I was a kid and grew up stuck to the Fast & Furious movies so I was obsessed with anything that can slide," he says. "I finally got my chance to own a road going RX-7 and fell in love with the car. Then I found this team on Facebook and I was following the build of their pink car and asked if they could build me a GT and instead we came to a deal for me to drive for them."

The Last Rotary Racer

Changes to the regulations in Super Car, not least the arrival of a control tyre when they have enjoyed a long-time supportive arrangement from a rival brand, has seen the team switching to the new-for-2019 PT Maxnitron Race Series. With an unrestricted ‘Open’ class in technical terms at the top of its pyramid, which is pretty much limited only by tyre sizes, that really appeals to an engineering challenge and seems to fit their ethic well.

The inaugural season started perfectly as James won the two races that comprised the first round, held at Bira Circuit, although technical issues reared their head come the return trip to Pattaya for the second round just a week ago, and that means it’s wide open for the season finale which comes up in November.

The Last Rotary Racer

But although James, driving the “yellow” car, had a tough weekend a well-rounded driver line-up means that there is a real strength in depth to the RX-7 contingent. U-tain Pongprapas has been with the programme from the early days and he’s always chasing for the running front positions and was on the podium while another pacey driver is Thai actor Andrew Cronin who enjoyed an excellent weekend in terms of unlocking speed.

So, is the project now where Titapon would have wished it to be? “We’re very happy with where we are at now,” he says. “At first we built the car and we didn’t know the best time we were going to get from it but once James came onboard and we had a good driver, we know where we’re at with the driver as he can drive the car faster.”

The Last Rotary Racer

They have built eight of these unique racecars now, a mix the two specification levels, and also have their own end of year race in Buriram. There have been overseas enquires about car builds as well as a lot of interest from rotary fans worldwide so it seems most logical that sometime in the not too distant future this ambitious programme will morph into its own ‘one make’ race category. Rotary Revolution’s ambitions are growing step by steady step and the future seems to be bright. It certainly seems that here in Thailand the art of developing racecars is still alive and kicking.

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    Text & Photo by:

  • Edd Ellison