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 horsepower from a 1.3-liter 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 horsepower. During its first run on the dyno, this RX-7 made 674 horsepower and 600 ft-lb of torque at 6,000 rpm while running a modest 10 psi of boost.
Gradually the boost is dialed up to 15, 20, and eventually 25 psi. Flames shoot from the RX-7's fender exhaust ports as the four-rotor engine cranks out 1,000 horsepower 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 30 psi. Horsepower tops 1,124 while torque drops to 841 ft-lb. Then a final run at 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 horsepower 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