The IPD is designed to provide nearly twice as much thrust as current space shuttle engines and to do it safer and more efficiently. It does this by using unique "full flow" preburners that provide more thrust than traditional rocket engines while operating at cooler temperatures.
To move that much fuel that quickly, a turbopump with high-speed turbines is used. In a traditional liquid-fuel rocket engine, a small amount of the fuel is "preburned," just enough to power up the turbopump so it can begin siphoning off the rest of the fuel into the combustion chamber. A similar process occurs with the oxidizer.
The IPD works differently. Instead of only send small amounts of fuel and oxidizer to the preburners, the IPD engine sends all of the fuel and all of the oxidizer. This causes the turbopump’s turbines to spin more quickly, producing more thrust. It’s like a pinwheel spinning faster as more wind is blown through its blades.
It'll be interesting to see if this lives up to it's hype.