The '86-'91 rendition isn't the quintessential RX-7 that you think of when considering Mazda's three-generation-spanning sports car. But it should be. With the final three years' models available with a 200hp turbocharged engine and RWD architecture, it's never been easier to pounce on boy racers in Civics—all for around four thousand bucks.
Brian Treffeisen knows this, which is precisely what led to his extensively modifying not the more predictable sequentially turbocharged third-generation version, but a 1988 model to which much time and money has been apportioned to, the most obvious of which has gone toward the car's 13B-RE engine transplant. Sourced from the '90–'95 Eunos Cosmo—Mazda's overseas-only, luxury line flagship car—the 235hp 1.3-liter marks the automotive world's first sequentially turbocharged rotary engine and features what are arguably the largest side ports among Mazda's entire 13B engine family. All of this means that the 13B-RE is capable of very good things. Treffeisen knows this, too, and has gone on to eek out exactly 405hp from the overhauled pistonless wonder.
Managing that sort of power from a lightly modified 13B of any sort isn't likely. The play for more begins with a single-turbo conversion based upon Garrett's GT35R, which mounts up by means of a custom-built, equal-length exhaust manifold. The one-off parts story doesn't end there, though. "I fabricated virtually every part on this vehicle," Brian says. "Most aftermarket support for the RX-7 [lacks] quality, and there are a lot of individuals whose theories and practices disagree with my own." A pair of TiAL MV-S wastegates that work alongside a MoTeC M800's built-in boost control capabilities allow consistent and repeatable power, all of which was dialed in on his own. As it turns out, Brian didn't just fabricate nearly everything on his RX-7, he tuned it, too, teaching himself how to do so as his build progressed.
Little expense was spared with all of this, like the MoTeC standalone that retails for more than most used cars. According to Treffeisen, he stopped counting after nearly $25,000 worth of mods. You would, too. The damage wasn't as painful as you might expect it would be, especially since the longtime Mazda fan's owned the car since 1997, smattering its upgrades out over the course of more than a decade and a half. The time spent making his RX-7 the car he knew it should be yielded lessons more valuable than whatever was spent on doubling its horsepower. Brian chose the RX-7 because of what he says is his "undying love for those spinning triangles." Often scowled at by piston purists or by those who are easily shied away by the inner workings of rotary engines, he will be the first to tell you how magical the internal combustion process free of pistons and connecting rods can be: "The rotary engine is incredibly durable when operated within its mechanical and thermal limits." Operating within its limitations is about as important as not cheaping out on quality parts, which is partially why Treffeisen's spent as much as he has. "Don't buy cheap parts, and spend your money where appropriate," he warns. "Quality OEM engine parts where appropriate, good aftermarket apex seals, and the best, most accurate ECU you can afford. Ignition timing and solid fuel delivery are crucial for a high-horsepower, forced-induction rotary."
Take a look at the car's fuel system and you won't be able to accuse Brian of not taking his own advice. Injector Dynamics 1,000cc/min. and 2,000cc/min. injectors line up against a set of Guru and CJ Motorsports rails while an Aeromotive 340lph pump draws alongside an already impressive Denso unit. Running lean because of a scant fuel system isn't likely to do. The engine itself was also strengthened accordingly. Here, its rotors and plates were cryo-treated and more durable apex seals—the Achilles heel of rotary engines—were sourced from RX-7 Specialties and added. The 13B-RE's cooling system was also updated with a customized Griffin aluminum radiator, steel-braided radiator lines, and the later-model RX-7's water pump and housing. He addressed potential driveline woes with a modified and re-worked six-speed RX-8 gearbox mated to a 4.3:1 Torsen-style rear differential. An Exedy twin-disc clutch and Driveshaft Shop aluminum driveshaft complete the lion's share of the RX-7's under-hood mods. Brian's affection for customizing his own parts doesn't stop with what's underneath the hood. One-off adjustable end links reside behind the 17-inch BBS rims and beskpoke bracing sit along each strut tower where pairs of Stance GR+ Pro coilovers can be found.
Mazda's second-generation RX-7 isn't necessarily the most sought-after of the nameplate's two-and-a-half-decade lifespan, but it should be, and Brian Treffeisen's 405hp example is here to tell you as much.
Engine 13B-RE engine; MazdaSpeed engine mounts; lightened, balanced and clearanced rotors; cryo-treated rotors and plates; RX-8 eccentric shaft and stationary gears; custom oil pump O-rings; RX-7 Specialties apex seals; custom oil pan brace; custom engine mount adapters; port-matched and ceramic coated manifolds; K&N air filter; custom high-mount intercooler; Denso in-tank lift pump; Aeromotive Stealth 340lph in-tank surge pump and fuel pressure regulator; CJ Motorsports primary fuel rail; Guru secondary fuel rail; Injector Dynamics 1,000cc primary and 2,000cc secondary fuel injectors; custom fuel cell; custom 4" downpipe; Magnaflow 3" mufflers; NGK spark plugs; Moroso spark plug wires; Bosch Motorsport ignition coils; Optima battery; Garrett GT35R turbo; custom exhaust manifold; dual TiAL MV-S wastegates; custom turbo elbow; GReddy blow-off valve; custom 2.5" to 3" intercooler piping; dual Mocal oil coolers; Griffin radiator; Aeromotive -16AN steel-braided radiator hoses; 16" AutoZone cooling fan; 13B-REW water pump and housing; custom mil-spec wiring harness
Engine Management MoTeC M800 ECU
Footwork & Chassis Stance GR+ Pro coilovers; Stance front camber plates; Racing Beat front anti-sway bar; custom end-links; front strut-tower brace with built-in engine torque brace; rear strut-tower brace; roll cage; Energy Suspension bushings
Brakes Wilwood calipers, proportioning valve and master cylinder; Carbotech pads; Goodridge steel-braided lines
Wheels & Tires 17x8"/17x9" +35 BBS wheels; 245/40R17 & 255/40R17 Toyo R1R tires; ARP wheel studs
Exterior Shine Auto Project front bumper; PPG Lotus Storm Titanium Metallic paint; Hella headlights
Interior Mazda RX-8 seats; custom seat brackets; Sparco steering wheel and Formula quick-release hub; ACC carpet; custom shift boot and emergency brake lever cover; AIM Sports MXL Strada digital display; Auto Meter boost and fuel level gauges; Aquamist HFS-3 gauge; Alpine head unit, amplifier and components; JL Audio subwoofer; Monster wires; Garmin GPS