How to make power without pistons

Marty's RX-7 is copping a bunch of upgrades [CLICK HERE], including going from frail twin turbochargers to one big aftermarket snail, but while throwing a larger turbo will make power there are some other secrets hiding inside the Mazda rotary engine. 

All engines are air pumps, so getting more air in and out will make more power. It's that simple, though there is a lot of science hiding inside that simple truth. While rotary engines are physically much smaller than comparative piston sluggers, their lower rotating mass and far superior inertia makes them an excellent way to turn air into horsepower. 

Back in the dark old days before EFI and glorious turbochargers, the best way to push more power out of your carby, NA 10A, 12A, or 13B was to hog out the intake and exhaust ports. This is where "street port", "bridge port", "J-port", "monster port" and the ultimate "peripheral port" engines came to be feared, as they could clean up the nastiest V8s and supercars.

The below image shows a  13B plate which has been modified with a "bridgeport" mod. Grinding out metal from the housings drags more air into, and then out of, the engine and lets the rotary use its single biggest weapon - its nearly unlimited RPM ceiling - to keep making power when piston engines are busy driving over their own crankshafts and sending slugs into a low orbit through the intake manifold. 

Pic from AusRotary.com

Going larger and larger with your ports was the rotary equivalant of adding larger and larger camshafts in a V8. They get an awesome, filthy idle with a screaming top-end, and if you've never heard a peripheral port rotary at idle or under power, then you're seriously missing out. CLICK HERE FOR SOME AWESOME IDLE

Ok, you will want to WATCH THIS ONE TOO. I don't like rotaries but I can respect any engine that sounds as obnoxious as that.

It's important to note that porting the heck out of your engine and then spinning it to Formula One type RPMs isn't conducive to reliability, You also butcher low-end response and torque, in much the same way as going too big on a cam in a V8. 

As with the V8 guys, however, rotary gurus worked out pretty quickly that displacement was the replacement for crazy ports. And Mazda proved this in 1991 with the R26B quad-rotor (see pic below) when they became the first Japanese manufacturer to win the Le Mans 24-hour. 

Adding rotors to a twin-rotor 10A, 12A, or 13B effectively increases the rotary's capacity. Mazda's biggest production rotary engine, the awesome triple-rotor 20B, is a rare beast highly valued by Wankel fiends and drag fans who want big power from their triangle-motor.

The cost of original triple rotors, and the desire for something exotic like a four-rotor engine, led to enough demand that the aftermarket responded. As the costs of computer design and CNC-machining dropped in the early part of the 21st Century, companies started bringing out aftermarket rotary engines featuring four, five, and even six rotors. 

The sound is really something else, and these engines are probably the equivalant of an aftermarket 600+ cubic-inch V8, but way more compact and capable of revving many factors higher. And the crazy thing is, they don't even need a turbo to do any of that.

However, with aggressive porting and big turbos you can bet these new four- and five-rotor combos are going to make enough power to walk pretty much anything with a piston.