Half of the U.S. new-car and truck fleet now is equipped with gasoline direct injection (also known as GDI)?which means the fuel is sprayed straight into the combustion chamber. This begs the question: What?s the next engine innovation about to leave the lab"
The answer is bringing fuel to the fire by two separate paths, and a few makers already are fitting their engines with both port and direct injection. Toyota introduced this technology, which it calls D-4S injection, on a V-6 more than a decade ago and now uses port and direct injection on its 2.0-liter flat-four (which is built by Subaru), 3.5-liter V-6, and 5.0-liter V-8. Audi has it on its 3.0-liter V-6 and 5.2-liter V-10 engines.

Toyota?s D-4S system was introduced on the 2006 Lexus IS350 3.5-liter V-6. Ford currently is the dominant player with what it calls dual-fuel, high-pressure direct injection (DI) and lower-pressure port injection (PI). Applications include turbocharged and naturally aspirated V-6 and V-8 gasoline engines?four in all?ranging in size from 2.7 to 5.0 liters. The 2017 F-150 Raptor flying pickup and the GT supercar both are powered by new 3.5-liter EcoBoost V-6s so equipped. Ground-bound F-150s also rely heavily on this technology with a dual-fueled base 3.3-liter V-6 and optional EcoBoost 2.7- and 3.5-liter V-6s. Ford?s most recently announced application thus far is the new 5.0-liter V-8 that will power the 2018 Mustang GT.
The Basics
Before delving into the fine points of teaming PI ...