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Mazda RX-7 FD3S - Unstoppable

Japan's 2007 RWD Tsukuba Record Holder

Dino Dalle Carbonare
Aug 1, 2008 SHARE
Turp_0808_01_z+mazda_rx7_fd3s+top_view Photo 1/27   |   Mazda RX-7 FD3S - Unstoppable

Last year, we visited Pan Speed to take a closer look at its RX-8 time attack car that has managed to lap Tsukuba in one minute flat, some 10 seconds faster than a stock RX-8 would ever hope to run. This year, however, the company got right back to its FD project with only one thing in mind: Breaking the 55-second barrier at Tsukuba. Pan Speed sure didn't hold back this time around with an all-new widebody conversion and a host of technical improvements,including a much more responsive engine. We met up with Pan Speed at Tsukuba for the car's first shakedown test.

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There's no denying that Mazda created a small masterpiece with the RX-7. No matter how you look at it, this rotary-powered sports car is both ingenious and simple. All of the main requisites for making a car perform well are there. It's relatively light, well balanced, adequately powered, and has an honest, no-nonsense rear-wheel-drive layout. Dig deeper and at its heart the incredibly compact 13B twin rotor Wankel engine buzzes away-its size allows it to be placed right back against the firewall. With such a great package to start off with, it's almost a given that a car of this nature would thrive in the aftermarket tuning world. Pan Speed, a company that has been at the forefront of rotary tuning, has just rolled out of its small workshop this monstrous widebody FD3S.

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This RX-7 managed to lap Tsukuba in 55.603 seconds at the Hyper Rev Lap Battle in December. Still running the older engine, it managed to finish in Second position overall, over a second behind the M-Speed GT-R. The target for this year is to go well into the 54 seconds, something that shouldn't be too hard to achieve with the new, more responsive engine and improved suspension setup.




Turp_0808_04_z+mazda_rx7_fd3s+pedals Photo 4/27   |   Mazda RX-7 FD3S - Unstoppable

The Pan Speed 13B meticulously prepared for its task by being subjected to a healthy dose of side porting. In rotary terms this is the equivalent of running some hot camshafts on a regular four-cycle piston engine. This is much more of a black art, however, than most will imagine and Pan Speed has had decades of experience in this sector with all sorts of hi-powered engines. Any amount of side porting can be detected as soon as the engine is turned on, as it seems to hunt up and down the revs until it settles into a menacing offbeat idle. Once the engine was closed up with upgraded apex seals it was onto the forced-induction improvements. To run the HKS T04Z, Pan Speed fabricated a 50mm manifold to feed the exhaust gasses into the turbine side of the blower. From there it's down to the massive 90mm straight titanium exhaust system to channel the spent gasses all the way to the back of the car.

Turp_0808_05_z+mazda_rx7_fd3s+motec_m800_controller Photo 5/27   |   Mazda RX-7 FD3S - Unstoppable

Boost is controlled by a Blitz RC external wastegate, which works in conjunction with the dual solenoids of the Blitz boost controller module. Actual control of all this, however, is handled by the Motec M800 ECU unit that limits boost at 1.2 bar. This allows the engine to be extremely responsive without developing stratospheric levels of power that wouldn't be adequate for track use. For this first step of tuning the engine pushes out 503 hp, which thanks to the 2,403 pounds gives a very healthy power-to-weight ratio. No form of filtering is applied to the T04Z, and a rather large aluminum air guide channels fresh air from the bumper intake directly to it, in an almost ram-air type layout.

Turp_0808_06_z+mazda_rx7_fd3s+rear_diffuser Photo 7/27   |   Mazda RX-7 FD3S - Unstoppable

Once the intake charge has been compressed it's then passed on to the flat-mounted Blitz intercooler, which for optimal airflow has been mounted in a V-pattern with the radiator. To create an almost airtight seal against the carbon hood, the intercooler is surrounded with a sort of seal, again made from carbon fiber. This allows the air passing through the radiator and intercooler to be expelled immediately via the hood's outlet. This helps keep engine bay temperatures as low as possible. More custom piping connects the intercooler to the Pan Speed intake U-bend, where the two small valves for boost control are fitted. From here it's on to the stock intake manifold.

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Turp_0808_09_z+mazda_rx7_fd3s+intercooler_tubing Photo 10/27   |   Lightweight alternator, water pump pulleys

Fueling is down to four 1,000cc/min injectors fed by two Bosch Motorsport pumps, which have no problem draining the tiny racing fuel tank in five laps of the circuit. On top of the Pan Speed radiator and air separator system, engine cooling is helped by a large core Pan Speed oil cooler located in the passenger side of the front bumper. The OS Giken twin-plate clutch has the job of handling all the power and torque the 13B pushes out, but its use is rather limited as full power upshifts are carried out without disengaging the clutch. This is because Pan Speed fitted a Hewland six-speed sequential gearbox-the same unit used on Super GT cars. This had to be custom fitted into the FD3S chassis and required a lot of modifications. It is then down to the OS Giken two-way limited-slip differential, which apportions torque efficiently to the two rear wheels.

Turp_0808_10_z+mazda_rx7_fd3s+v_mount_intercooler Photo 11/27   |   Pan Speed triple-row radiator V-mounted Blitz intercooler

This RX-7 project started off with a fully stripped and bare FD3S chassis. A lot of time went into spot welding, but not as much time as was spent in cutting and boxing off specific areas to increase rigidity. The most visible are the front and rear suspension turrets, which were rebuilt allowing Pan Speed to fine-tune its damper mounting points. A great deal of labor went into modifying the transmission tunnel, which needed to accept the Hewland sequential. Once the tunnel was shaped it was layered with carbon fiber to help stiffen that area of the chassis. This is a process we've seen done on Nismo Z-tune cars. It was then on to the rollcage, again custom built and welded into position with additional bracing into the chassis, just like a race car. In fact, there is very little difference in the preparation of this car to a full-out Super GT racer. Once the chassis was finished it was painted in metallic silver to clean things up.

Turp_0808_11_z+mazda_rx7_fd3s+hks_t04z_turbine Photo 12/27   |   HKS TO4Z set to spool up to 1.2 bar (21.8 psi)

The driving position was pushed back a little to help balance the weight. Next to him the battery assembly was also relocated to create a better balance. The Tanida full bucket seat is joined by a Tanida steering wheel mounted on an extended steering rack with snap off boss. On the center of the wheel the Pan Speed guys fitted the small Motec LCD display onto a piece of carbon fiber-a true race car look. The stock pedals were eliminated and replaced with an adjustable pedal box, which could be tailored to the driver's preferences. The now redundant stock instrument binnacle has been plated off with carbon while the center console has been custom built (yes, with more carbon fiber) and houses all of the necessary switchgear. A fully molded carbon-fiber transmission tunnel was also created, really giving the interior a Super GT feel. From here, the gear lever of the Hewland has been custom fitted and linked, as well as the smaller lever to engage reverse. The racing fuel tank has been located in the trunk area of the interior and has been carefully positioned for the best possible weight distribution.

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Turp_0808_16_z+mazda_rx7_fd3s+atl_racing_fuel_cell Photo 16/27   |   Mazda RX-7 FD3S - Unstoppable

The link with the racing world continues with the exterior. Hanaoka-san of DMAC International, who is responsible for the design of many Super GT cars, was called in to create the wider body. The main benefit of such a kit is to push the wheels further out from the chassis, therefore helping the car handle better on track. This allowed for some very aggressive fenders, like at the front with the louvered top section and the angular rear over-fenders. The front bumper features an integrated front splitter as well as some canards to help with high-speed downforce. The air dams are all functional and feed the V-mount radiator and intercooler setup, the large air intake for the turbine and the two intakes for brake cooling and the oil cooler. The chunky side skirts continue the widening of the body and fuse with the rear fenders to create a very aggressive profile. The rear end is pure GT racer with a series of air outlets created on the rear side of the fenders as well as on the center part of the bumper. This has all been done to create as much downforce as possible and channel turbulent air from the underside of the car. The rear carbon diffuser also helps out in this department by stabilizing the rear end while the carbon GT-wing offers various settings to adjust downforce.

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To save as much weight as possible the hood and doors are made of carbon fiber, while the rear hatch is a removable FRP item with a polycarbonate windscreen. Gold Volk Racing CE28N 18-inch wheels wrapped in Dunlop 03G semi-slick tires complete the exterior. Providing a low-down stance and helping with the handling are the hlins dampers, which have been custom valved and gassed by Pan Speed. Hyperco springs and an array of suspension parts, which are kept confidential, join the dampers. Braking is taken care of by Brembo Racing forged calipers all around, six-pot at the front and four-pots at the rear. These bite down on Performance Friction two-piece grooved rotors with pads. The stock master cylinder has been replaced with an AP Racing item, offering more adjustability and performance.

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Only time will tell if this is the record-breaking machine Pan Speed is hoping for. This car will no doubt become one of the fastest machines in Japan. During the shakedown tests it was lapping Tsukuba in 57 seconds and the driver, who before that day had never driven the car, said there's a lot of potential in the package. All eyes will be on this Pan Speed RX-7 come December when tuners meet at Tsukuba for the Super Lap Battle. This is one appointment we won't miss.

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Specs
Engine/Drivetrain
Pan Speed side-ported 13B (654cc)
Pan Speed 50mm custom exhaust manifoldHKS T04Z turbine
Blitz RC external wastegate
Pan Speed 90mm custom titanium exhaust
Custom built Blitz V-mounted intercooler
Custom piping
Custom air intake for turbine intake
Pan Speed intake U-bend pipe with twin circulators for boost control
Blitz twin solenoids for boost control (controlled by Motec)
Pan Speed triple-row radiator V-mounted with intercooler
Air-separator tank
Pan Speed oil cooler
Custom oil catch tank
Lightweight alternator, water pump pulleys
ATL racing fuel tank (in trunk)
Stainless steel braided fuel lines
1,000cc injectors
Motec M800 ECU (custom wired)
OS Giken twin-plate clutch
Six-speed Hewland sequential gearbox, custom fitted
OS Giken two-way limited-slip differential

Turp_0808_36_z+mazda_rx7_fd3s+relocated_strut_tower Photo 20/27   |   Mazda RX-7 FD3S - Unstoppable

Chassis/Suspension
Custom valved and gassed hlins adjustable dampers
Hyperco springs
Pan Speed custom relocated front-strut tower bar
Pan Speed solid type bushes
Cusco top-mount spacers

Wheels/Tires/Brakes
Rays Engineering Volk Racing CE28N 10.5JJx18 +18
Dunlop 03G 265/40/18
AP Racing master cylinder
Brembo Racing six-pot forged front calipers
Brembo Racing four-pot forged rear calipers
Performance Friction two-piece grooved rotors
Performance Friction race pads
Braided brake lines

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Turp_0808_27_z+mazda_rx7_fd3s+side_view_at_track Photo 24/27   |   Mazda RX-7 FD3S - Unstoppable

Exterior/Interior
Pan Speed 2008 widebody conversion
Front bumper
Front bumper side canards
Front wide fenders
Headlight conversion with fixed projectors and yellow cover
Carbon vented hood
Side skirts
Rear overfenders
Rear bumper
Rear hatch with polycarbonate
Carbon doors
Carbon side mirrors
Rear carbon diffuser
Carbon GT-type wing
Pan Speed yellow paint and original decals

Interior
Fully spot welded chassis
Welded-in rollcage
Custom stiffening plating on critical locations
Custom re-built and stiffened suspension turrets
Custom transmission tunnel with dry-carbon stiffening
Tanida full bucket seat
Scorch Racing racing harness
Tanida Alcantara racing steering wheel
Custom carbon center on steering wheel for Motec display and over-boost buttonSnap-off boss
Motec LCD display
Custom plated-off stock instrument binnacle
Custom carbon center console with switchgear
Dry-carbon custom transmission tunnel trim
Custom shit lever and leverage mechanism (including reverse lever)
Adjustable pedal box
Passenger-side mounted battery

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By Dino Dalle Carbonare
122 Articles

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