The third-generation FD Mazda RX-7 is one of the ultimate sports cars of the 1990s. The styling looks shrink-wrapped around a lightweight platform. Its 13B engine produced 252 bhp from a 1.3-litre engine thanks to a sequential twin-turbo. But while the rotary engine promised many things, torque was one thing it failed to deliver. That's what makes this RX-7's power output so incredible.
Using a four-rotor engine instead of the stock two-rotor gives this RX-7 a sound that's a cross between a superbike and an electric drill. If you've ever heard the Le Mans-winning Mazda 787B, it's virtually identical, making you wonder if both cars share the same R26B four-rotor engine.
The power numbers are certainly close. In Le Mans trim, the 787B made between 600 and 700 bhp. During its first run on the dyno, this RX-7 made 674 bhp and 600 ft-lb of torque at 6,000 rpm while running a modest 0.7 bar (10 psi) of boost.
Gradually the boost is dialled up to 1 bar (15 psi), 1.4 bar (20 psi), and eventually 1.7 bar (25 psi). Flames shoot from the RX-7's wing/fender exhaust ports as the four-rotor engine cranks out 1,000 bhp and 847 ft-lb of torque. The sound is otherworldly. Even with ear protection, it's got to rattle your fillings and threaten to burst your ear drums.
Finally, they go for 2 bar (30 psi). Horsepower tops 1,124 while torque drops to 841 ft-lb. Then a final run at 2.4 bar (35 psi), which is 2.5 times the atmosphere at sea level. The four-rotor seems to shrug off the pressure, fully in its element, producing 1,145 bhp and 925 ft-lb of torque. The car seems to have more to give, but Rob Dahm says he's too scared to push harder.
Before they load the RX-7 back in the covered trailer, Dahm makes a couple of passes on the deserted street. Unlike a stock RX-7, this car has all-wheel drive and is running drag radials. Even then, it wants to go sideways, spinning all four wheels as the unearthly wail of the four-rotor engine fills the twilight.
Source: Rob Dahm via YouTube