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SR20 FD3S Mazda RX-7 - With Purpose

The final word on what a time attack car should be

Aaron Bonk
Apr 3, 2015
Photographer: Martin Fordal Persson

Forget about any period-correct, manufacturer-specific rule book that you think there is. Show weenies will never stop chastising the guy with the non-JDM- compliant air filter on his four-door Civic, but for everyone else, going faster need not show allegiance to any one particular make. Like ridding an FD3S RX-7 chassis of nearly everything Mazda, draping it in carbon-fiber, and fitting it with what its owner considers a more capable SR20VET.

1995 mazda RX7 custom carbon fiber body 03 Photo 2/24   |   Complete custom carbon aero all built in—house by Valtonen.

Before the car's all-original and ever-adapting aerodynamic pieces were conceived for time attack service, Finland's Valtonen Motorsport's third-generation coupe was brought to life and commissioned by Falken Tire for drift duty. Right away, the Nissan powerplant was transplanted into place, partly because of its effectiveness but also because of team principal Christian Valtonen's familiarity with the factory-turbocharged 2.0L engine.

1995 mazda RX7 tractive RD905 sequential transmission 07 Photo 3/24   |   Drivetrain consists of a sequential gearbox; BMW rear diff and custom driveshafts.

A gifted powerplant Valtonen's SR engine is with its Holset turbo and completely overhauled and forged insides, but it's everything surrounding the four-cylinder that makes this RX-7 so special. Call it a tube-frame chassis, though, and you'll be wrong; this FD retains enough of its native structure, like its firewall and suspension-mounting points, to hold on to its unibody heritage. Still, much of what you'd expect from any tube-frame embodiment worth its weight in chrome-moly and welding rod is here. The engine has been positioned near mid-ship, and structural enhancements behind the cockpit remain minimal—both efforts to throw weight around in all the right ways and, ultimately, make it all handle just right.

It isn't the un-rotary-like box of pistons and rods or the expanse of gold-clad triangulation that made you stop and look, though. The aero alone is enough to upset Mazda purists and defy physics all at once. Ask Valtonen, though, and he'll tell you it's all very much a work in progress, consisting of all sorts of complicated development and trial and error, but all for the sake of more grip. The towering and fully adjustable rear wing commands your attention first, but then your eyes are quickly drawn up front toward the ventilated fenders that seem to swallow the tires. A series of ducts and vents has been placed strategically throughout the one-piece front end that are responsible for cooling the brakes and engine bay, among other things, and the cooling system itself has been relocated behind the cabin. Every bit of it is something you'd expect from any well-funded race team or something like the almost-2-million-dollar Pagani Zonda R, of which Valtonen's RX-7 shares at least a few visual cues—not some privateer racing team from Northern Europe.

1995 mazda RX7 SR20VET swap 11 Photo 7/24   |   SR2OVET swap makes up to 800 hp depending on tuning.

Turns out that privateer racing teams are quite capable, and Valtonen and company has proved as much by building its RX-7 almost entirely in-house. Valtonen will argue that Nissan's SR line may be more capable than the original sequentially turbocharged 13B, but that doesn't mean the 2.0L didn't undergo an extensive rebuild. Similar to the SR20DET, the SR20VET was used more sparingly by Nissan and is among the first of the SR family to feature variable valve timing. The rebuilt bottom end is based on the Pulsar GTI-R's crankshaft that features wider bearing journals, and wider bearing journals mean better protection against the forces of a whole lot of combustion. The rest of the rotating assembly Valtonen remains tight-lipped about but is based on custom-sized forged pistons from CP. The engine's original wet-sump oiling system has also been retained in lieu of the typical dry-sump system you'd normally find on a car of this caliber, but that's proved to be OK. That's mostly because of the modifications Valtonen's made to the oil passages throughout the block, the better-performing oil pump—also from the Pulsar—and the Accusump accumulator that, not unlike a dry-sump system, stores oil externally and directs it toward important parts like bearings when needed.

1995 mazda RX7 custom carbon fiber body 10 Photo 8/24   |   Get ready for World Time Attack Challenge in Australia. Valtonen plans to make the journey from Europe to race against the best!

Despite the Nissan powertrain, the drivetrain remains foreign to both the engine and chassis. Here, Valtonen looked to Swedish firm Tractive for its RD905 sequential transmission. Sequential gearboxes do away with the H-pattern shifting formation you're used to and allow all five gears to be flicked through in a straight line. The sequential transmission's dog gears also mean shifts happen quicker when compared to synchromesh-style gearboxes that interrupt torque output every time the shifter changes spots. The rest of the drivetrain is made up of a BMW rear differential and custom shafts that tie it all back to the transmission and to the rear wheels.

The chassis, the powertrain, the gearbox, the aero, even the differential, all of them were sourced from their own corners of the automotive world but brought together not for the sake of satisfying any purists—because none of it will—but for going faster. Valtonen doesn't hide the fact that all of this—even the FD3S chassis that's still revered after nearly two and a half decades—is little more than a tool or a means to an end of which a handful of other unibodies would've done just as well. In an era in which enthusiasts may be chastised for bizarro engine swaps and make-disguising body mods in the name of better performance, it's all very much a welcomed change of pace.

1995 mazda RX7 custom carbon fiber body 05 Photo 12/24   |   SR20 FD3S Mazda RX-7 - With Purpose
1995 mazda RX7 advan wheels 02 Photo 16/24   |   SR20 FD3S Mazda RX-7 - With Purpose
1995 mazda RX7 MOMO steering wheel 04 Photo 20/24   |   SR20 FD3S Mazda RX-7 - With Purpose
1995 mazda RX7 custom carbon fiber body 09 Photo 24/24   |   SR20 FD3S Mazda RX-7 - With Purpose
By Aaron Bonk
405 Articles
SR20 FD3S Mazda RX-7 - With Purpose
Tuning Menu
Owner: Valtonen Motorsport
Hometown: Porvoo, Finland
Engine: Nissan SR20VET swap; Pulsar GTI-R crankshaft; custom CP pistons; custom connecting rods and billet crankshaft girdle; ACL Race Series engine bearings; modified Pulsar oil pump; Accusump oil accumulator; modified oiling passages; ARP head studs; Power Enterprise head gasket; Kelford Cams camshafts; Tomei adjustable camshaft gears; Supertech Performance oversized valves, valvesprings, and liners; custom titanium retainers; modified rocker arms; modified timing chain tensioner; ATI engine damper; custom intake manifold; custom 70mm throttle body; Holset HX series turbocharger; TiAL 60mm wastegate; Garrett intercooler; custom end tanks and piping; custom exhaust manifold; custom 4.5-inch exhaust and muffler; custom overflow tanks; four Bosch Motorsport fuel pumps; Injector Dynamics 2,300 cc/min fuel injectors; BMW ignition coils; Denso Iridium spark plugs
Drivetrain: Tractive RD905 sequential transmission, custom chrome-moly flywheel; Alcon triple-disc clutch, custom bellhousing, driveshafts; BMW 210mm differential; Carbonetic limited-slip differential
Engine Management: Haltech Platinum Sport 2000 engine management system
Footwork & Chassis: Nitron Racing shocks; left-hand-drive conversion; custom front control arms; modified front uprights and rear suspension
Brakes: Alcon six-piston calipers and rotors; Carbonetic pads; Tilton pedal assembly; HEL lines
Wheels & Tires: 18x10.5" front, 18x12" rear Advan wheels; tires vary depending on conditions
Exterior: Custom carbon-fiber body
Interior: Valtonen Motorsport display; MOMO steering wheel; Sparco Evo II seat and harness; Happy Racer passenger seat and harness
WWW: valtonenmotorsport.fi; mackin-ind.com; turbobygarrett.com

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