Almost ten years ago, Mazda released the third generation RX-7-chassis code FD3S-to a new generation of automotive enthusiasts who, before the FD, may not have considered owning a rotary-powered vehicle. During it's three-model-year production run, the FD3S RX-7 generated a huge aftermarket support platform and the car quickly became associated with the purpose-built street performance cars on the road at that time. Due to a number of restrictrictions, especially the increasingly stringent smog restrictions here in the States, the FD3S saw its time come and go. With heavy research and development, Mazda has sought to replace the FD wundercar with a smoother, more powerful car-the Renesis-powered RX-8. However, there are still those that see the older RX-7 as a potent platform upon which to build. Loi Song, owner and proprietor of Sportcar Motion in San Marcos, Calif., is one such person.
Having owned several high-powered American muscle cars, Loi is no stranger to inordinate amounts of power. And, while his 1994 RX-7 felt strong and agile "out of the box," as the proprietor of an automotive performance parts resale and installation, he knew that there was no way he could leave well enough alone. With a specific tuning path in mind, Loi set out and secured his first performance-related upgrade: the "FD3ST04" license plate. The "FD3S" moniker relayed the chassis information, while the "T04" referred to something more important-the heart of the powerplant.
True, the RX7 is powered by Mazda's 13B rotary motor, and that would technically be the heart, but what makes Loi's car faster than a speeding bullet is the HKS T04R single turbocharger. This massive, high-output turbocharger replaces the OEM twin sequential units, connecting to a custom 4-in downpipe before exiting via HKS' 4-in titanium Ti Offroad exhaust system. Sportcar Motion technicians insured the life of the rotary motor by first cryogenically treating the rotor housing; this process significantly aligns the lattice structure of the alloy while retaining its form, increasing the tensile strength and durability of the final product. For rotary owners, this all but cures the proverbial thorn in the 13B's foot so take note.
Working in conjunction with the HKS turbine is a custom "street port" of the rotor housing, done by the technicians at Sportcar Motion. Porting a rotary motor is similar to changing camshafts in a piston engine, which modifies intake and exhaust gas durations and, subsequently, volumes. While Loi wishes to keep his porting techniques secret, he does tell us that with his performance modifications in place, the XS Engineering-tuned, A'PEXi FC Commander-controlled 13B puts down 445 hp at just over 15 lb of boost-and that's with 91-octane pump gas.
Additional engine mods are provided by the HKS Type S front-mounted intercooler to lower the temperature of the charge air, twin HKS Super Sequential Blowoff valves, a Fluidyne radiator to keep the notoriously hot engine running cooler.